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Dhiraj Gupta

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Papers by Dhiraj Gupta

Update on Etripamil Nasal Spray for the At-home Treatment of Acute Paroxysmal Supraventricular Tachycardia

Heart International, 2021

he current treatment of sustained paroxysmal supraventricular tachycardia (PSVT) often requires a... more he current treatment of sustained paroxysmal supraventricular tachycardia (PSVT) often requires attendance at a medical facility. This burden is driven by the lack of an effective self-administered treatment for PSVT. Etripamil (Milestone Pharmaceuticals, Saint-Laurent, QC, Canada) is a novel intra-nasal preparation of a rapidly effective but short-acting calcium-channel blocker, which shows promise in offering out-of-hospital treatment for patients with PSVT. Studies, to date, have demonstrated good tolerability and potential efficacy, with a safety profile that is acceptable for unsupervised self-administration. This article reviews the current epidemiology and international guidelines for the treatment of acute PSVT, the pharmacology and clinical trial evidence behind the novel agent etripamil, and considers its potential role in the management of patients with PSVT.

Left Atrial Appendage Occlusion—A Choice or a Last Resort? How to Approach the Patient

Interventional Cardiology Clinics, 2022

Left atrial appendage (LAA) occlusion is emerging as a viable alternative to oral anticoagulation... more Left atrial appendage (LAA) occlusion is emerging as a viable alternative to oral anticoagulation in high-risk patients with atrial fibrillation. However, there remains limited evidence for this approach, especially in certain subgroups, and therefore patient selection is an important aspect of treatment. Here, the authors present arguments for LAA occlusion as either a last resort versus patient choice by evaluating contemporary studies on this topic and discuss practical steps in the approach of patients who may be suitable for LAA occlusion. Overall, an individualized and multidisciplinary team approach should be adopted in patients who are being considered for LAA occlusion.

Percutaneous Left Atrial Appendage Occlusion: A View From the UK

Arrhythmia & Electrophysiology Review, 2020

AF is associated with an increased risk of thromboembolic events, which is usually managed with o... more AF is associated with an increased risk of thromboembolic events, which is usually managed with oral anticoagulation therapy. However, despite a broad range of anticoagulant options and improved uptake in anticoagulation over the past decade, there are some limitations to this approach. Percutaneous left atrial appendage occlusion has been shown to be an effective alternative in this setting, and population data suggest a clear demand for this procedure. Over the past decade, several important changes to the commissioning and delivery of this service have occurred in the UK. In this article, the authors describe the use of percutaneous left atrial appendage occlusion in the UK and discuss the challenges that lie ahead.

Open surgery for ventricular tachycardia following failed stereotactic radiation treatment: A bailout when a parachute hasn’t helped

HeartRhythm Case Reports, 2021

Left Atrial Appendage Occlusion: Past, Present and Future

Thrombosis and Haemostasis, 2020

There are several situations whereby oral anticoagulation may be unsuitable for stroke prevention... more There are several situations whereby oral anticoagulation may be unsuitable for stroke prevention in patients with atrial fibrillation (AF). Percutaneous left atrial appendage (LAA) occlusion has received much attention in this area. Various devices have already been developed and tested for this purpose. Data from registries and cohort studies have indicated favourable short- and long-term outcomes with LAA occlusion, and several international guidelines recommend its use in AF patients with contraindications to oral anticoagulation. However, prospective controlled trials in this very population are lacking. Furthermore, while modelling studies on cost analyses have suggested that LAA occlusion may be a cost-effective strategy compared with standard medical therapy, these have not been performed in high-risk patients who may have limited survival in the medium to long term. Thus, while LAA occlusion offers promise, there is a strong need for additional research to investigate its e...

Efficacy and safety of aspirin for primary prevention of cardiovascular events: a meta-analysis and trial sequential analysis of randomized controlled trials

European Heart Journal, 2018

The role of aspirin in the primary prevention setting is continuously evolving. Recent randomized... more

56-26: Left atrial appendage occlusion for stroke prevention in atrial appendage occlusion for stroke prevention in atrial fibrillation: contemporary commissioning through evaluation experience from the United Kingdom

EP Europace, 2016

Introduction: Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging c... more Introduction: Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging can be used to visualize regions of preexisting and ablation-induced scarring in the left atrium (LA) myocardium. The determination of preexisting fibrosis vs postablation scarring may be important for treatment stratification of patients with atrial fibrillation (AF) and affect future strategies for catheter ablation. This study aimed to define the characteristics of preexisting and ablation-induced LA wall LGE in patients who underwent pulmonary vein isolation (PVI) for AF. Methods: 20 patients underwent PVI for AF. LGE CMR was prospectively performed before and 3 months after catheter ablation. For every single ablation point, the intracardiac locations were projected onto an individual MRI-derived 3D LA shell. This allowed the LGE CMR signal intensities (SI) to be projected on to the LA anatomy from electroanatomical mapping. The image intensity ratio (IIR), defined as LA myocardial LGE CMR SI divided by the mean LA blood pool intensity, and LA myocardial wall thickness were calculated on pre-and postablation images. The ablation lesions could thus be directly analyzed as every vertex on the fused LA shell had an individual LGE label. Results: Data analysis was performed on a total of 894 ablation points and 346 pairs of preand postablation axial LGE CMR planes. A total number of 280250 vertices (11210/patient) were analyzed on the fused LA shells. Postablation LGE demonstrated a significant higher IIR as compared to preexisting LGE (1.40 þ/-0.21 vs 1.18 þ/-0.17 p ¼ 0.001), indicating greater contrast uptake and denser scar. LA wall thickness was as well significantly reduced in postablation LGE regions (2.06 þ/-0.32mm vs 2.40 þ/-0.44mm p ¼ 0.001). Conclusion: CMR demonstrates that LA regions with postablation LGE have an increased contrast uptake and a thinner wall myocardium. This observation can assist in understanding LA remodeling processes and may allow a more informed assessment of the underlying atrial substrate.

Contact force-sensing catheters and increased risk of atrioesophageal fistula: is the tool to blame or the workmen?

Heart Rhythm, 2017

Surgical septal myectomy or alcohol septal ablation: which approach offers better outcomes for patients with hypertrophic obstructive cardiomyopathy?

Interactive cardiovascular and thoracic surgery, Jan 28, 2017

A best evidence topic in cardiac surgery was written according to a structured protocol. The ques... more A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether surgical septal myectomy (SM) is more beneficial than alcohol septal ablation (ASA) in patients with hypertrophic obstructive cardiomyopathy. Altogether 218 articles were found using the reported search, of which 15 studies represented the best evidence to answer the clinical question. There were 14 observational studies and 1 meta-analysis study. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these articles are tabulated. Surgical SM was generally performed in younger patients whereas percutaneous ASA was favoured in patients with advanced age and significant co-morbidities. In a large study comprising 716 patients, the reduction of median residual left ventricular outflow tract (LVOT) gradient at 3 months was comparable after ASA (102 ± 52-10 mmHg) and SM (92 ± 39-9 mmHg). The New Yor...

Letter by Bartoletti et al Regarding Article, “Ablation of Persistent Atrial Fibrillation Targeting Low-Voltage Areas With Selective Activation Characteristics”

Circulation: Arrhythmia and Electrophysiology, 2016

We congratulate Jadidi et al 1 on their interesting article, "Ablation of Persistent Atrial Fibri... more We congratulate Jadidi et al 1 on their interesting article, "Ablation of Persistent Atrial Fibrillation Targeting Low-Voltage Areas With Selective Activation Characteristics." They prospectively enrolled 85 patients with persistent atrial fibrillation undergoing ablation with a stepwise approach. No further lesions beyond pulmonary vein isolation (PVI) were delivered in 23 (27%), who were in sinus rhythm at the start or reverted to sinus rhythm during PVI. In the remaining 62 patients, further lesions were delivered within low-voltage areas (LVA) in the left atrium or in their borders. They found that these 62 cases had higher success rates compared with PVI-only controls chosen from a historical population. A couple of observations are in order:

Ablation index, a novel marker of ablation lesion quality: prediction of pulmonary vein reconnection at repeat electrophysiology study and regional differences in target values

Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology, Jan 31, 2016

Force-Time Integral (FTI) is commonly used as a marker of ablation lesion quality during pulmonar... more Force-Time Integral (FTI) is commonly used as a marker of ablation lesion quality during pulmonary vein isolation (PVI), but does not incorporate power. Ablation Index (AI) is a novel lesion quality marker that utilizes contact force, time, and power in a weighted formula. Furthermore, only a single FTI target value has been suggested despite regional variation in left atrial wall thickness. We aimed to study AI's and FTI's relationships with PV reconnection at repeat electrophysiology study, and regional threshold values that predicted no reconnection. Forty paroxysmal atrial fibrillation patients underwent contact force-guided PVI, and the minimum and mean AI and FTI values for each segment were identified according to a 12-segment model. All patients underwent repeat electrophysiology study at 2 months, regardless of symptoms, to identify sites of PV reconnection. Late PV reconnection was seen in 53 (11%) segments in 25 (62%) patients. Reconnected segments had significant...

Primary Care Atrial Fibrillation Service: outcomes from consultant-led anticoagulation assessment clinics in the primary care setting in the UK

BMJ Open, 2015

Stroke-risk in atrial fibrillation (AF) can be significantly reduced by appropriate thromboemboli... more Stroke-risk in atrial fibrillation (AF) can be significantly reduced by appropriate thromboembolic prophylaxis. However, National Institute for Health and Care Excellence estimates suggest that up to half of eligible patients with AF are not anticoagulated, with severe consequences for stroke prevention. We aimed to determine the outcome of an innovative Primary Care AF (PCAF) service on anticoagulation uptake in a cohort of high-risk patients with AF in the UK. Methods: The PCAF service is a novel cooperative pathway providing specialist resources within general practitioner (GP) practices. It utilises a four-phase protocol to identify high-risk patients with AF (CHA 2 DS 2-VASc ≥1) who are suboptimally anticoagulated, and delivers Consultant-led anticoagulation assessment within the local GP practice. We assessed rates of anticoagulation in highrisk patients before and after PCAF service intervention, and determined compliance with newly-initiated anticoagulation at follow-up. Results: The PCAF service was delivered in 56 GP practices (population 386 624; AF prevalence 2.1%) between June 2012 and June 2014. 1579 high-risk patients with AF with suboptimal anticoagulation (either not taking any anticoagulation or taking warfarin but with a low time-in-therapeutic-range) were invited for review, with 86% attending. Of 1063 eligible patients on no anticoagulation, 1020 (96%) agreed to start warfarin (459 (43%)) or a non-vitamin K antagonist oral anticoagulant (NOAC, 561 (53%)). The overall proportion of eligible patients receiving anticoagulation improved from 77% to 95% (p<0.0001). Additionally, 111/121 (92%) patients suboptimally treated with warfarin agreed to switch to a NOAC. Audit of eight practices after 195 (185-606) days showed that 90% of patients started on a new anticoagulant therapy had continued treatment. Based on data extrapolated from previous studies, around 30-35 strokes per year may have been prevented in these previously under-treated high-risk patients. Conclusions: Systematic identification of patients with AF with high stroke-risk and consultation in PCAF consultant-led clinics effectively delivers oral anticoagulation to high-risk patients with AF in the community.

42 * The primary care atrial fibrillation (PCAF) service: consultant-led anticoagulation assessment clinics in the primary care setting increase the uptake of anticoagulation therapy in AF patients at high-risk of stroke

Europace, 2014

Introduction: AF confers a 5-6% annual risk of stroke, though this can be significantly reduced b... more Introduction: AF confers a 5-6% annual risk of stroke, though this can be significantly reduced by appropriate thromboembolic prophylaxis. However, NICE has estimated that 46% of patients that should be anticoagulated are not. This may be in part due to GP and patient concerns over anticoagulation and lack of awareness of recently-released novel oral anticoagulants (NOACs). We present outcomes from an innovative Consultant-led anticoagulation assessment service: the Primary Care AF (PCAF) service. Methods: The PCAF pathway involves 4 phases. Phase 1: for each enrolled GP practice, the "true" AF register is established by identifying patients with AF not already on the register. Phase 2: High-risk patients (CHA2DS2-VASc score 1) who either are not on anticoagulation or are on warfarin but with a sub-optimal TTR are identified. Phase 3: Identified patients are invited for review by letter, with phone reminders 1 week and 1 day prior. Phase 4: PCAF clinics are delivered within the patients' GP practice by a Consultant Cardiologist or Stroke Physician. Where appropriate, anticoagulation is prescribed in accordance with NICE/local formulary guidelines. Results: 42 GP practices have been enrolled to date, covering a population of 284,945 (AF prevalence 2.0%). After clarifying the AF registers (Phase 1), 5426 high-risk patients were identified, of whom 2398 (44.2%) were not on anticoagulation (Phase 2). After case note reviews to exclude patients in whom AF had resolved or there was a contra-indication to anticoagulation, 1169 high-risk patients not on anticoagulation were invited for review (Phase 3). 1014 patients (87%) attended, of whom 761 (75.0%) had AF and eligibility for anticoagulation confirmed (Phase 4). 745 (97.9%) of these patients agreed to commence anticoagulation (43.0% warfarin, 57.0% NOAC). Taking into account all exclusions, the rate of anticoagulation in eligible patients increased from 76.8% (3028 of 3944) to 95.7% (3773 of 3944) following PCAF service intervention. In addition, 261 of 3028 patients on warfarin (8.6%) had a sub-optimal TTR, of whom 211 (80.8%) attended for review. 137 patients (64.9%) were advised to continue with warfarin after a review of compliance and recent INRs; 74 (35.1%) were offered a NOAC, with 67 (90.5%) agreeing to switch. Based on a NNT with warfarin for 1 year to prevent 1 stroke in a mixed primary/secondary prevention group of 25 from NICE/DoH analyses, 29.8 strokes have been prevented in the 745 high-risk patients not previously on anticoagulation. With the addition of patients with a sub-optimal TTR who have now switched to a NOAC, it can be estimated that .30 strokes have been prevented amongst the 42 GP practices. Conclusion: By bridging the primary/secondary care boundary, Consultant-led anticoagulation clinics in GP practices via the PCAF service have proven to be highly effective in identifying AF patients at high risk of stroke, optimising their treatment and preventing strokes.

2D analytical modeling of threshold voltage of doped short-channel triple-material double-gate(TM-DG) MOSFETs

In this paper, a short-channel threshold voltage model is presented for triple-material double-ga... more In this paper, a short-channel threshold voltage model is presented for triple-material double-gate(TM-DG) MOSFET with uniform doping profile in the channel region. To obtain the channel potential expression, the two-dimensional (2D) Poisson's equation has been solved using the parabolic potential approximation with suitable boundary conditions. Subsequently, the surface potential expression has been employed to derive an analytical expression of thresholod. The threshold voltage variation with various device parameters has been shown. To validate the model, ATLAS TM based numerical simulation results have been used.

Cardiac arrest in athletes and resuscitation

Journal of the Intensive Care Society, 2015

6Long term outcomes after persistent AF ablation: six year data from a high volume UK centre

EP Europace, 2014

Demographic and clinical profile of prosthetic valve thrombosis: 10 year experience from a third world center

Journal of Molecular and Cellular Cardiology, 2001

The Impact of CT Image Integration into an Electroanatomic Mapping System on Clinical Outcomes of Catheter Ablation of Atrial Fibrillation

Journal of Cardiovascular Electrophysiology, 2006

A detailed appreciation of left atrial/pulmonary vein (LA/PV) anatomy may be important in improvi... more A detailed appreciation of left atrial/pulmonary vein (LA/PV) anatomy may be important in improving the safety and success of catheter ablation (CA) for atrial fibrillation (AF). The aim of this nonrandomized study was to determine the impact of computerized tomography (CT) image integration into a 3-dimensional (3D) mapping system on the clinical outcome of patients undergoing CA for AF. Ninety-four patients (age: 56 +/- 10 years) with AF (paroxysmal 46, persistent 48) underwent wide encirclement of ipsilateral PV pairs using irrigated radiofrequency ablation with the endpoint of electrical isolation. Ablation was guided by 3D mapping alone (electroanatomic 24, noncontact 23) in 47 (3DM group) patients and by CT image integration (Cartomerge) in 47 (CT group). In persistent AF, a combination of linear ablation and targeted ablation of complex fractionated electrograms was also performed. Successful PV electrical isolation did not differ between the two groups. A significant reduction in fluoroscopy times was demonstrated in the CT group (49 +/- 27 minutes vs 3DM group 62 +/- 26 minutes, P = 0.03). Arrhythmia recurrence was reduced in the CT group (32% vs 51% in the 3DM group, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01). In 30 symptomatic patients (12 CT and 18 3DM), repeat procedures for AF (13 in 3DM and 5 CT, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or = 0.10) and AT (5 in 3DM and 7 CT, P = NS) were performed. Overall success on 7-day monitor off antiarrhythmic drugs was achieved in 60% in the 3DM group when compared with 83% in the CT group (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) at a follow-up of 25 +/- 5 weeks. CA for AF guided by CT integration was associated with reduced fluoroscopy times, arrhythmia recurrence, and increased restoration of sinus rhythm. Improved visualization of complex LA geometries might improve the safety and success of CA for AF.

Improving Safety in Catheter Ablation for Atrial Fibrillation: A Prospective Study of the Use of Ultrasound to Guide Vascular Access

Journal of Cardiovascular Electrophysiology, 2014

Vascular Ultrasound for AFAIntroductionThe most frequent complications of AF ablation (AFA) are r... more Vascular Ultrasound for AFAIntroductionThe most frequent complications of AF ablation (AFA) are related to vascular access, but there is little evidence as to how these can be minimized.MethodsConsecutive patients undergoing AFA at a high‐volume center received either standard care (Group S) or routine ultrasound‐guided vascular access (Group U). Vascular complications were assessed before hospital discharge and by means of postal questionnaire 1 month later. Outcome measures were BARC 2+ bleeding complications, postprocedural pain, and prolonged bruising.ResultsPatients in Group S (n = 146) and U (n = 163) were well matched at baseline. Follow‐up questionnaires were received from 92.6%. Patients in Group U were significantly less likely to have a BARC 2+ bleed, 10.4% versus 19.9% P = 0.02, were less likely to suffer groin pain after discharge (27.1% vs. 42.8%; P = 0.006) and were less likely to experience prolonged local bruising (21.5% vs. 40.4%; P = 0.001). Multivariable logistic...

Factors influencing late course of residual valvular and infundibular gradients following pulmonary valve balloon dilatation

International Journal of Cardiology, 2001

Though acute and follow-up benefits of pulmonary valve balloon dilatation (PVBD) for pulmonic val... more Though acute and follow-up benefits of pulmonary valve balloon dilatation (PVBD) for pulmonic valve stenosis are well known, the late course of residual gradients at individual valvular and infundibular levels is not well described. Furthermore, the factors influencing this late course have not been studied. We assessed the transpulmonary gradients by echo-Doppler in 96 patients (61 male, mean age 10.7 years) at a mean follow-up interval of 58.8+/-32.1 months (minimum 2 years) following PVBD. The patients were divided into three groups based on the residual gradients at valvular and infundibular levels immediately following PVBD as assessed by pull-back of an end-hole catheter across the right ventricular outflow tract: Group A with minor pressure gradients at both valvular and infundibular levels of less than 30 mmHg (n=60, 62.5%), Group B with predominantly infundibular gradients of more than 30 mmHg with a valvular gradient of less than 30 mmHg (n=27, 28.1%), and Group C with a residual valvular gradient of greater than 30 mmHg irrespective of the infundibular gradient (n=9, 9.4%). Demographic characteristics, hemodynamic parameters and procedural variables were correlated with the change in gradient at follow-up (late fall) and with long-term results. The mean follow-up trans-pulmonary gradient was 20+/-14 mmHg which was significantly lower than that immediately post-PVBD (43+/-32 mmHg), P&lt;0.001. The late fall (mean 24+/-29, range -55 to 110 mmHg) varied widely depending upon the acute result group: patients in Groups A and B showed significant late fall of 9+/-12 mmHg (P&lt;0.05 for follow-up gradient compared to that following PVBD) and 58+/-31 mmHg (P&lt;0.0001), respectively, while patients in Group C showed an insignificant late fall of 14+/-37 mmHg (P=0.21). In particular, each one of the patients in Group B showed decrease in trans-pulmonary gradients. On multivariate analysis, the extent of infundibular gradient emerged as the most important predictor of late fall (coefficient of determination 75%, P&lt;0.0001). Patients who underwent PVBD at less than 2 years of age had a significantly greater late fall (41+/-33 mmHg) as compared to older patients (22+/-25 mmHg), P&lt;0.05. A sub-optimal long-term result (transpulmonary gradient &gt;25 mmHg, n=24) was significantly related to older age (P&lt;0.001), dysplastic valve morphology (P=0.002), greater baseline trans-pulmonary gradients (P&lt;0.001) and higher post-PVBD gradients (P=0.04). The long-term course of patients following PVBD depends upon the site and magnitude of the residual gradients. Even high residual infundibular gradients show marked reduction at follow-up, especially in infancy.

Update on Etripamil Nasal Spray for the At-home Treatment of Acute Paroxysmal Supraventricular Tachycardia

Heart International, 2021

he current treatment of sustained paroxysmal supraventricular tachycardia (PSVT) often requires a... more he current treatment of sustained paroxysmal supraventricular tachycardia (PSVT) often requires attendance at a medical facility. This burden is driven by the lack of an effective self-administered treatment for PSVT. Etripamil (Milestone Pharmaceuticals, Saint-Laurent, QC, Canada) is a novel intra-nasal preparation of a rapidly effective but short-acting calcium-channel blocker, which shows promise in offering out-of-hospital treatment for patients with PSVT. Studies, to date, have demonstrated good tolerability and potential efficacy, with a safety profile that is acceptable for unsupervised self-administration. This article reviews the current epidemiology and international guidelines for the treatment of acute PSVT, the pharmacology and clinical trial evidence behind the novel agent etripamil, and considers its potential role in the management of patients with PSVT.

Left Atrial Appendage Occlusion—A Choice or a Last Resort? How to Approach the Patient

Interventional Cardiology Clinics, 2022

Left atrial appendage (LAA) occlusion is emerging as a viable alternative to oral anticoagulation... more Left atrial appendage (LAA) occlusion is emerging as a viable alternative to oral anticoagulation in high-risk patients with atrial fibrillation. However, there remains limited evidence for this approach, especially in certain subgroups, and therefore patient selection is an important aspect of treatment. Here, the authors present arguments for LAA occlusion as either a last resort versus patient choice by evaluating contemporary studies on this topic and discuss practical steps in the approach of patients who may be suitable for LAA occlusion. Overall, an individualized and multidisciplinary team approach should be adopted in patients who are being considered for LAA occlusion.

Percutaneous Left Atrial Appendage Occlusion: A View From the UK

Arrhythmia & Electrophysiology Review, 2020

AF is associated with an increased risk of thromboembolic events, which is usually managed with o... more AF is associated with an increased risk of thromboembolic events, which is usually managed with oral anticoagulation therapy. However, despite a broad range of anticoagulant options and improved uptake in anticoagulation over the past decade, there are some limitations to this approach. Percutaneous left atrial appendage occlusion has been shown to be an effective alternative in this setting, and population data suggest a clear demand for this procedure. Over the past decade, several important changes to the commissioning and delivery of this service have occurred in the UK. In this article, the authors describe the use of percutaneous left atrial appendage occlusion in the UK and discuss the challenges that lie ahead.

Open surgery for ventricular tachycardia following failed stereotactic radiation treatment: A bailout when a parachute hasn’t helped

HeartRhythm Case Reports, 2021

Left Atrial Appendage Occlusion: Past, Present and Future

Thrombosis and Haemostasis, 2020

There are several situations whereby oral anticoagulation may be unsuitable for stroke prevention... more There are several situations whereby oral anticoagulation may be unsuitable for stroke prevention in patients with atrial fibrillation (AF). Percutaneous left atrial appendage (LAA) occlusion has received much attention in this area. Various devices have already been developed and tested for this purpose. Data from registries and cohort studies have indicated favourable short- and long-term outcomes with LAA occlusion, and several international guidelines recommend its use in AF patients with contraindications to oral anticoagulation. However, prospective controlled trials in this very population are lacking. Furthermore, while modelling studies on cost analyses have suggested that LAA occlusion may be a cost-effective strategy compared with standard medical therapy, these have not been performed in high-risk patients who may have limited survival in the medium to long term. Thus, while LAA occlusion offers promise, there is a strong need for additional research to investigate its e...

Efficacy and safety of aspirin for primary prevention of cardiovascular events: a meta-analysis and trial sequential analysis of randomized controlled trials

European Heart Journal, 2018

The role of aspirin in the primary prevention setting is continuously evolving. Recent randomized... more

56-26: Left atrial appendage occlusion for stroke prevention in atrial appendage occlusion for stroke prevention in atrial fibrillation: contemporary commissioning through evaluation experience from the United Kingdom

EP Europace, 2016

Introduction: Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging c... more Introduction: Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging can be used to visualize regions of preexisting and ablation-induced scarring in the left atrium (LA) myocardium. The determination of preexisting fibrosis vs postablation scarring may be important for treatment stratification of patients with atrial fibrillation (AF) and affect future strategies for catheter ablation. This study aimed to define the characteristics of preexisting and ablation-induced LA wall LGE in patients who underwent pulmonary vein isolation (PVI) for AF. Methods: 20 patients underwent PVI for AF. LGE CMR was prospectively performed before and 3 months after catheter ablation. For every single ablation point, the intracardiac locations were projected onto an individual MRI-derived 3D LA shell. This allowed the LGE CMR signal intensities (SI) to be projected on to the LA anatomy from electroanatomical mapping. The image intensity ratio (IIR), defined as LA myocardial LGE CMR SI divided by the mean LA blood pool intensity, and LA myocardial wall thickness were calculated on pre-and postablation images. The ablation lesions could thus be directly analyzed as every vertex on the fused LA shell had an individual LGE label. Results: Data analysis was performed on a total of 894 ablation points and 346 pairs of preand postablation axial LGE CMR planes. A total number of 280250 vertices (11210/patient) were analyzed on the fused LA shells. Postablation LGE demonstrated a significant higher IIR as compared to preexisting LGE (1.40 þ/-0.21 vs 1.18 þ/-0.17 p ¼ 0.001), indicating greater contrast uptake and denser scar. LA wall thickness was as well significantly reduced in postablation LGE regions (2.06 þ/-0.32mm vs 2.40 þ/-0.44mm p ¼ 0.001). Conclusion: CMR demonstrates that LA regions with postablation LGE have an increased contrast uptake and a thinner wall myocardium. This observation can assist in understanding LA remodeling processes and may allow a more informed assessment of the underlying atrial substrate.

Contact force-sensing catheters and increased risk of atrioesophageal fistula: is the tool to blame or the workmen?

Heart Rhythm, 2017

Surgical septal myectomy or alcohol septal ablation: which approach offers better outcomes for patients with hypertrophic obstructive cardiomyopathy?

Interactive cardiovascular and thoracic surgery, Jan 28, 2017

A best evidence topic in cardiac surgery was written according to a structured protocol. The ques... more A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether surgical septal myectomy (SM) is more beneficial than alcohol septal ablation (ASA) in patients with hypertrophic obstructive cardiomyopathy. Altogether 218 articles were found using the reported search, of which 15 studies represented the best evidence to answer the clinical question. There were 14 observational studies and 1 meta-analysis study. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these articles are tabulated. Surgical SM was generally performed in younger patients whereas percutaneous ASA was favoured in patients with advanced age and significant co-morbidities. In a large study comprising 716 patients, the reduction of median residual left ventricular outflow tract (LVOT) gradient at 3 months was comparable after ASA (102 ± 52-10 mmHg) and SM (92 ± 39-9 mmHg). The New Yor...

Letter by Bartoletti et al Regarding Article, “Ablation of Persistent Atrial Fibrillation Targeting Low-Voltage Areas With Selective Activation Characteristics”

Circulation: Arrhythmia and Electrophysiology, 2016

We congratulate Jadidi et al 1 on their interesting article, "Ablation of Persistent Atrial Fibri... more We congratulate Jadidi et al 1 on their interesting article, "Ablation of Persistent Atrial Fibrillation Targeting Low-Voltage Areas With Selective Activation Characteristics." They prospectively enrolled 85 patients with persistent atrial fibrillation undergoing ablation with a stepwise approach. No further lesions beyond pulmonary vein isolation (PVI) were delivered in 23 (27%), who were in sinus rhythm at the start or reverted to sinus rhythm during PVI. In the remaining 62 patients, further lesions were delivered within low-voltage areas (LVA) in the left atrium or in their borders. They found that these 62 cases had higher success rates compared with PVI-only controls chosen from a historical population. A couple of observations are in order:

Ablation index, a novel marker of ablation lesion quality: prediction of pulmonary vein reconnection at repeat electrophysiology study and regional differences in target values

Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology, Jan 31, 2016

Force-Time Integral (FTI) is commonly used as a marker of ablation lesion quality during pulmonar... more Force-Time Integral (FTI) is commonly used as a marker of ablation lesion quality during pulmonary vein isolation (PVI), but does not incorporate power. Ablation Index (AI) is a novel lesion quality marker that utilizes contact force, time, and power in a weighted formula. Furthermore, only a single FTI target value has been suggested despite regional variation in left atrial wall thickness. We aimed to study AI's and FTI's relationships with PV reconnection at repeat electrophysiology study, and regional threshold values that predicted no reconnection. Forty paroxysmal atrial fibrillation patients underwent contact force-guided PVI, and the minimum and mean AI and FTI values for each segment were identified according to a 12-segment model. All patients underwent repeat electrophysiology study at 2 months, regardless of symptoms, to identify sites of PV reconnection. Late PV reconnection was seen in 53 (11%) segments in 25 (62%) patients. Reconnected segments had significant...

Primary Care Atrial Fibrillation Service: outcomes from consultant-led anticoagulation assessment clinics in the primary care setting in the UK

BMJ Open, 2015

Stroke-risk in atrial fibrillation (AF) can be significantly reduced by appropriate thromboemboli... more Stroke-risk in atrial fibrillation (AF) can be significantly reduced by appropriate thromboembolic prophylaxis. However, National Institute for Health and Care Excellence estimates suggest that up to half of eligible patients with AF are not anticoagulated, with severe consequences for stroke prevention. We aimed to determine the outcome of an innovative Primary Care AF (PCAF) service on anticoagulation uptake in a cohort of high-risk patients with AF in the UK. Methods: The PCAF service is a novel cooperative pathway providing specialist resources within general practitioner (GP) practices. It utilises a four-phase protocol to identify high-risk patients with AF (CHA 2 DS 2-VASc ≥1) who are suboptimally anticoagulated, and delivers Consultant-led anticoagulation assessment within the local GP practice. We assessed rates of anticoagulation in highrisk patients before and after PCAF service intervention, and determined compliance with newly-initiated anticoagulation at follow-up. Results: The PCAF service was delivered in 56 GP practices (population 386 624; AF prevalence 2.1%) between June 2012 and June 2014. 1579 high-risk patients with AF with suboptimal anticoagulation (either not taking any anticoagulation or taking warfarin but with a low time-in-therapeutic-range) were invited for review, with 86% attending. Of 1063 eligible patients on no anticoagulation, 1020 (96%) agreed to start warfarin (459 (43%)) or a non-vitamin K antagonist oral anticoagulant (NOAC, 561 (53%)). The overall proportion of eligible patients receiving anticoagulation improved from 77% to 95% (p<0.0001). Additionally, 111/121 (92%) patients suboptimally treated with warfarin agreed to switch to a NOAC. Audit of eight practices after 195 (185-606) days showed that 90% of patients started on a new anticoagulant therapy had continued treatment. Based on data extrapolated from previous studies, around 30-35 strokes per year may have been prevented in these previously under-treated high-risk patients. Conclusions: Systematic identification of patients with AF with high stroke-risk and consultation in PCAF consultant-led clinics effectively delivers oral anticoagulation to high-risk patients with AF in the community.

42 * The primary care atrial fibrillation (PCAF) service: consultant-led anticoagulation assessment clinics in the primary care setting increase the uptake of anticoagulation therapy in AF patients at high-risk of stroke

Europace, 2014

Introduction: AF confers a 5-6% annual risk of stroke, though this can be significantly reduced b... more Introduction: AF confers a 5-6% annual risk of stroke, though this can be significantly reduced by appropriate thromboembolic prophylaxis. However, NICE has estimated that 46% of patients that should be anticoagulated are not. This may be in part due to GP and patient concerns over anticoagulation and lack of awareness of recently-released novel oral anticoagulants (NOACs). We present outcomes from an innovative Consultant-led anticoagulation assessment service: the Primary Care AF (PCAF) service. Methods: The PCAF pathway involves 4 phases. Phase 1: for each enrolled GP practice, the "true" AF register is established by identifying patients with AF not already on the register. Phase 2: High-risk patients (CHA2DS2-VASc score 1) who either are not on anticoagulation or are on warfarin but with a sub-optimal TTR are identified. Phase 3: Identified patients are invited for review by letter, with phone reminders 1 week and 1 day prior. Phase 4: PCAF clinics are delivered within the patients' GP practice by a Consultant Cardiologist or Stroke Physician. Where appropriate, anticoagulation is prescribed in accordance with NICE/local formulary guidelines. Results: 42 GP practices have been enrolled to date, covering a population of 284,945 (AF prevalence 2.0%). After clarifying the AF registers (Phase 1), 5426 high-risk patients were identified, of whom 2398 (44.2%) were not on anticoagulation (Phase 2). After case note reviews to exclude patients in whom AF had resolved or there was a contra-indication to anticoagulation, 1169 high-risk patients not on anticoagulation were invited for review (Phase 3). 1014 patients (87%) attended, of whom 761 (75.0%) had AF and eligibility for anticoagulation confirmed (Phase 4). 745 (97.9%) of these patients agreed to commence anticoagulation (43.0% warfarin, 57.0% NOAC). Taking into account all exclusions, the rate of anticoagulation in eligible patients increased from 76.8% (3028 of 3944) to 95.7% (3773 of 3944) following PCAF service intervention. In addition, 261 of 3028 patients on warfarin (8.6%) had a sub-optimal TTR, of whom 211 (80.8%) attended for review. 137 patients (64.9%) were advised to continue with warfarin after a review of compliance and recent INRs; 74 (35.1%) were offered a NOAC, with 67 (90.5%) agreeing to switch. Based on a NNT with warfarin for 1 year to prevent 1 stroke in a mixed primary/secondary prevention group of 25 from NICE/DoH analyses, 29.8 strokes have been prevented in the 745 high-risk patients not previously on anticoagulation. With the addition of patients with a sub-optimal TTR who have now switched to a NOAC, it can be estimated that .30 strokes have been prevented amongst the 42 GP practices. Conclusion: By bridging the primary/secondary care boundary, Consultant-led anticoagulation clinics in GP practices via the PCAF service have proven to be highly effective in identifying AF patients at high risk of stroke, optimising their treatment and preventing strokes.

2D analytical modeling of threshold voltage of doped short-channel triple-material double-gate(TM-DG) MOSFETs

In this paper, a short-channel threshold voltage model is presented for triple-material double-ga... more In this paper, a short-channel threshold voltage model is presented for triple-material double-gate(TM-DG) MOSFET with uniform doping profile in the channel region. To obtain the channel potential expression, the two-dimensional (2D) Poisson's equation has been solved using the parabolic potential approximation with suitable boundary conditions. Subsequently, the surface potential expression has been employed to derive an analytical expression of thresholod. The threshold voltage variation with various device parameters has been shown. To validate the model, ATLAS TM based numerical simulation results have been used.

Cardiac arrest in athletes and resuscitation

Journal of the Intensive Care Society, 2015

6Long term outcomes after persistent AF ablation: six year data from a high volume UK centre

EP Europace, 2014

Demographic and clinical profile of prosthetic valve thrombosis: 10 year experience from a third world center

Journal of Molecular and Cellular Cardiology, 2001

The Impact of CT Image Integration into an Electroanatomic Mapping System on Clinical Outcomes of Catheter Ablation of Atrial Fibrillation

Journal of Cardiovascular Electrophysiology, 2006

A detailed appreciation of left atrial/pulmonary vein (LA/PV) anatomy may be important in improvi... more A detailed appreciation of left atrial/pulmonary vein (LA/PV) anatomy may be important in improving the safety and success of catheter ablation (CA) for atrial fibrillation (AF). The aim of this nonrandomized study was to determine the impact of computerized tomography (CT) image integration into a 3-dimensional (3D) mapping system on the clinical outcome of patients undergoing CA for AF. Ninety-four patients (age: 56 +/- 10 years) with AF (paroxysmal 46, persistent 48) underwent wide encirclement of ipsilateral PV pairs using irrigated radiofrequency ablation with the endpoint of electrical isolation. Ablation was guided by 3D mapping alone (electroanatomic 24, noncontact 23) in 47 (3DM group) patients and by CT image integration (Cartomerge) in 47 (CT group). In persistent AF, a combination of linear ablation and targeted ablation of complex fractionated electrograms was also performed. Successful PV electrical isolation did not differ between the two groups. A significant reduction in fluoroscopy times was demonstrated in the CT group (49 +/- 27 minutes vs 3DM group 62 +/- 26 minutes, P = 0.03). Arrhythmia recurrence was reduced in the CT group (32% vs 51% in the 3DM group, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01). In 30 symptomatic patients (12 CT and 18 3DM), repeat procedures for AF (13 in 3DM and 5 CT, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or = 0.10) and AT (5 in 3DM and 7 CT, P = NS) were performed. Overall success on 7-day monitor off antiarrhythmic drugs was achieved in 60% in the 3DM group when compared with 83% in the CT group (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) at a follow-up of 25 +/- 5 weeks. CA for AF guided by CT integration was associated with reduced fluoroscopy times, arrhythmia recurrence, and increased restoration of sinus rhythm. Improved visualization of complex LA geometries might improve the safety and success of CA for AF.

Improving Safety in Catheter Ablation for Atrial Fibrillation: A Prospective Study of the Use of Ultrasound to Guide Vascular Access

Journal of Cardiovascular Electrophysiology, 2014

Vascular Ultrasound for AFAIntroductionThe most frequent complications of AF ablation (AFA) are r... more Vascular Ultrasound for AFAIntroductionThe most frequent complications of AF ablation (AFA) are related to vascular access, but there is little evidence as to how these can be minimized.MethodsConsecutive patients undergoing AFA at a high‐volume center received either standard care (Group S) or routine ultrasound‐guided vascular access (Group U). Vascular complications were assessed before hospital discharge and by means of postal questionnaire 1 month later. Outcome measures were BARC 2+ bleeding complications, postprocedural pain, and prolonged bruising.ResultsPatients in Group S (n = 146) and U (n = 163) were well matched at baseline. Follow‐up questionnaires were received from 92.6%. Patients in Group U were significantly less likely to have a BARC 2+ bleed, 10.4% versus 19.9% P = 0.02, were less likely to suffer groin pain after discharge (27.1% vs. 42.8%; P = 0.006) and were less likely to experience prolonged local bruising (21.5% vs. 40.4%; P = 0.001). Multivariable logistic...

Factors influencing late course of residual valvular and infundibular gradients following pulmonary valve balloon dilatation

International Journal of Cardiology, 2001

Though acute and follow-up benefits of pulmonary valve balloon dilatation (PVBD) for pulmonic val... more Though acute and follow-up benefits of pulmonary valve balloon dilatation (PVBD) for pulmonic valve stenosis are well known, the late course of residual gradients at individual valvular and infundibular levels is not well described. Furthermore, the factors influencing this late course have not been studied. We assessed the transpulmonary gradients by echo-Doppler in 96 patients (61 male, mean age 10.7 years) at a mean follow-up interval of 58.8+/-32.1 months (minimum 2 years) following PVBD. The patients were divided into three groups based on the residual gradients at valvular and infundibular levels immediately following PVBD as assessed by pull-back of an end-hole catheter across the right ventricular outflow tract: Group A with minor pressure gradients at both valvular and infundibular levels of less than 30 mmHg (n=60, 62.5%), Group B with predominantly infundibular gradients of more than 30 mmHg with a valvular gradient of less than 30 mmHg (n=27, 28.1%), and Group C with a residual valvular gradient of greater than 30 mmHg irrespective of the infundibular gradient (n=9, 9.4%). Demographic characteristics, hemodynamic parameters and procedural variables were correlated with the change in gradient at follow-up (late fall) and with long-term results. The mean follow-up trans-pulmonary gradient was 20+/-14 mmHg which was significantly lower than that immediately post-PVBD (43+/-32 mmHg), P&lt;0.001. The late fall (mean 24+/-29, range -55 to 110 mmHg) varied widely depending upon the acute result group: patients in Groups A and B showed significant late fall of 9+/-12 mmHg (P&lt;0.05 for follow-up gradient compared to that following PVBD) and 58+/-31 mmHg (P&lt;0.0001), respectively, while patients in Group C showed an insignificant late fall of 14+/-37 mmHg (P=0.21). In particular, each one of the patients in Group B showed decrease in trans-pulmonary gradients. On multivariate analysis, the extent of infundibular gradient emerged as the most important predictor of late fall (coefficient of determination 75%, P&lt;0.0001). Patients who underwent PVBD at less than 2 years of age had a significantly greater late fall (41+/-33 mmHg) as compared to older patients (22+/-25 mmHg), P&lt;0.05. A sub-optimal long-term result (transpulmonary gradient &gt;25 mmHg, n=24) was significantly related to older age (P&lt;0.001), dysplastic valve morphology (P=0.002), greater baseline trans-pulmonary gradients (P&lt;0.001) and higher post-PVBD gradients (P=0.04). The long-term course of patients following PVBD depends upon the site and magnitude of the residual gradients. Even high residual infundibular gradients show marked reduction at follow-up, especially in infancy.