Rahul Samanta

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Papers by Rahul Samanta

Influence of obesity on ventricular arrhythmias in chronic ischemic cardiomyopathy

B-PO04-086 Interatrial Septal Fat Reduces Interatrial Conduction Independent of Atrial Low-Voltage Burden in Patients with Atrial Fibrillation: Implications for Atrial Fibrillation Vulnerability in Obesity and Atrial Fibrillation Recurrence Following Ablation

Heart Rhythm

Interatrial Septal Fat Contributes to Interatrial Conduction Delay and Atrial Fibrillation Recurrence Following Ablation

Circulation: Arrhythmia and Electrophysiology

Minimalistic strategy for coronary sinus lead implant: A single tool capable of electrophysiological mapping, pressure measurement, and angiography

Pacing and Clinical Electrophysiology

Left ventricular (LV) lead implantation for cardiac resynchronization therapy (CRT) may be confou... more Left ventricular (LV) lead implantation for cardiac resynchronization therapy (CRT) may be confounded by contrast load during attempted cannulation and lead dislodgement during guiding catheter splitting. An LV lead implant system with a steerable single catheter that completely avoids the use of guiding catheters when needed, acquires atrioventricular electrograms, measures intracardiac pressures, permits CS angiography, and has the ability to direct a coronary angioplasty wire that will lead the final delivery of LV lead into a CS tributary, may help limit contrast use and avoid lead dislodgement at CS guide sheath removal.

Outcomes and Complication Rate of Ventricular Tachycardia Ablation in a Large Quaternery Metropolitan Australian Hospital

Heart, Lung and Circulation

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Optimisation and Utility of Endocardial Catheter Based Electroanatomical Mapping for Discrimination of Adipose Infiltration within Left Ventricular Scar in an Ovine Post Infarct Model

Heart, Lung and Circulation

Arrhythmias and Sudden Cardiac Death in End Stage Renal Disease: Epidemiology, Risk Factors and Management

Canadian Journal of Cardiology

Patients with end-stage renal disease (ESRD) are predisposed to heart rhythm disorders resulting ... more Patients with end-stage renal disease (ESRD) are predisposed to heart rhythm disorders resulting in significant morbidity and mortality. Bradyarrhythmia appears to be more prevalent than ventricular tachyarrhythmias. There is also a high incidence of sudden cardiac death (SCD) in this group of patients, which cannot be explained only by traditional cardiac risk factors. The reported incidence and prevalence of arrhythmias and SCD is quite variable mainly because of the different study populations and recording techniques. The mechanism of SCD in patients with ESRD is also not clear. Although traditionally the thinking has been that ventricular arrhythmias are the main contributor to SCD, recent studies with implantable loop recorders have highlighted the role of bradyarrhythmias. The pathophysiological processes resulting in arrhythmia and SCD in patients with ESRD are unique. Some of the risk factors, including dialysate composition, timing, and frequency, are modifiable and hence provide an option for interventions to potentially reduce SCD. In addition, there might be a relationship with the timing of dialysis with SCD tending to occur during the long interdialytic period. Patients with ESRD have a higher likelihood of requiring pacemaker implantation; however, they also have a higher risk of device-related complications. The limited data available regarding the role of the implantable cardioverter defibrillator to prevent SCD in patients with ESRD have shown conflicting results. Future research is needed to develop appropriate risk stratification tools to identify patients who will benefit from such interventions and to assess their safety and efficacy.

Influence of BMI on short and long-term outcomes in patients with STEMI and LV dysfunction

Heart, Lung and Circulation

BACKGROUND Recent studies suggestan obesity paradox in individuals with myocardial infarction wit... more BACKGROUND Recent studies suggestan obesity paradox in individuals with myocardial infarction with better outcomes in obese relative to normal weight patients. We assessed the influence of body mass index (BMI) on early and long-term outcomes in patients with ST elevation myocardial infarction (STEMI) and left ventricular (LV) dysfunction. METHODS Outcomes were assessed according to BMI status in 478 consecutive patients with STEMI and LV dysfunction (ejection fraction (EF)<40%) admitted to Westmead Hospital between 1 January 2004 and 16 April 2014. Normal weight, overweight and obesity were defined as BMI < 25, 25-29.9, and ≥30 kg/m2, respectively. RESULTS Obese patients were significantly younger (p = 0.01) and were more likely to have hypertension and diabetes (p = 0.04 and 0.001 respectively). In hospital outcomes and 30-day major adverse cardiac events (MACE) were similar in all three groups. There was no difference in recurrent myocardial infarction (MI) and target vessel revascularisation (TVR) during long-term follow-up (mean follow-up 809 days). Overall mortality following hospital discharge was significantly lower in overweight and obese patients. Adjusted hazard ratio for all-cause mortality in normal weight patients compared to overweight patients was 2.4 (95% C.I 1.1-5.3, p= -0.03). The adjusted hazard ratio for all-cause mortality in normal weight patients in comparison to obese patients was 2.7 (95% C.I, 1 -7.4, p = 0.05). Left ventricular ejection fraction (LVEF) and age were other predictors of all-cause mortality. CONCLUSIONS Normal weight, overweight and obese patients with STEMI and LV dysfunction had similar in hospital outcomes and 30-day outcomes. Long-term all-cause mortality was, however, higher in normal weight patients suggesting the presence of an obesity paradox in this cohort.

Influence of Body Mass Index on Recurrence of Ventricular Arrhythmia, Mortality in Defibrillator Recipients With Ischaemic Cardiomyopathy

Heart, Lung and Circulation

BACKGROUND Obesity is associated with increased risk of cardiovascular disease. There is little k... more BACKGROUND Obesity is associated with increased risk of cardiovascular disease. There is little known, however, about the influence of body mass index (BMI) on spontaneously occurring ventricular arrhythmias in patients with ischaemic heart disease. We sought to examine the effect of BMI on the ventricular arrhythmia (VA) recurrence and mortality in defibrillator recipients with ischaemic cardiomyopathy. METHODS Consecutive patients (n = 123) with ischaemic cardiomyopathy (left ventricular ejection fraction (LVEF) ≤ 40%) and a primary or secondary prevention defibrillator were included. Patients were classified according to their BMI as being normal (18.5-24.99, n = 54/ 43.9%), overweight (2 -29.99, n = 43/ 35%) or obese (>30, n = 26/20.3%). RESULTS The primary combined endpoint of VA recurrence and mortality occurred in 36%, 5.4% and 11.5% of patients with normal, overweight and obese BMI (p = 0.001). When adjusting for risk factors such as ejection fraction, age and triple vessel disease, on multivariable analysis, normal BMI remained a significant predictor for the primary outcome (Hazard Ratio, Normal vs Overweight = 7.1, 95% CI 1.8-25, p = 0.002: Hazard Ratio, Normal vs Obese = 5.5, 95% CI 1.11-25, p = 0.033. There was a non-significant trend towards reduced survival in patients with normal weight in comparison to overweight and obese patients (p = 0.08). CONCLUSION In defibrillator recipients with ischaemic cardiomyopathy, BMI appears to be a significant predictor for the combined primary outcome of spontaneously occurring ventricular arrhythmias and mortality. Normal BMI, compared to overweight and obese patients had worse outcomes, suggesting the presence of the obesity paradox in ventricular arrhythmogenesis late post infarction.

The Use of Intravenous Sotalol in Cardiac Arrhythmias

Heart, Lung and Circulation

Sotalol is a non-selective beta-adrenergic blocking agent without intrinsic sympathomimetic activ... more Sotalol is a non-selective beta-adrenergic blocking agent without intrinsic sympathomimetic activity. It has the additional unique property of producing pronounced prolongation of the cardiac action potential duration. Sotalol therapy has been indicated for the management of supraventricular arrhythmias, refractory life threatening ventricular arrhythmias and atrial fibrillation/flutter. Until recently, sotalol was only available in the oral form, however, it was approved for intravenous administration by the US Food & Drug Administration (FDA). The current recommendations are for sotalol 75-150mg to be administered intravenously over 5hours. This rate of administration does not reflect the majority of the research that has been performed with regards to intravenous sotalol. Also, the safety of intravenous bolus dosing of 100mg over 1 and 5minutes has previously been demonstrated. The antiarrhythmic action of sotalol depends on its ability to prolong refractoriness in the nodal and extra nodal tissue. Hence, by giving a lower dose over a long duration, patients may not necessarily benefit from its anti-arrhythmic potential. The purpose of this article is to review the research that has been conducted with regards to dosage and safety of intravenous sotalol, its electrophysiological effects and finally the spectrum of arrhythmias in which it has been used to date.

Influence of BMI on inducible ventricular tachycardia and mortality in patients with myocardial infarction and left ventricular dysfunction: The obesity paradox

International journal of cardiology, Jan 15, 2018

There is little known about the influence of obesity on ventricular electrical remodelling after ... more There is little known about the influence of obesity on ventricular electrical remodelling after myocardial infarction. The aim of our study was to assess the relationship between body mass index (BMI) and the primary outcome of inducible-VT and the secondary outcome of all-cause mortality in consecutive patients who presented with ST elevation myocardial infarction (STEMI) and LV-dysfunction (LVEF ≤ 40%). Consecutive patients (n = 380) with STEMI and LV-dysfunction (LVEF ≤ 40%) underwent electrophysiological (EP) studies for risk-stratification. Inducible-VT ≥200 ms cycle-length (CL) with one to four extra-stimuli (ES) was considered abnormal. Patients were classified according their body mass index (BMI) to be normal (18.5-24.9), overweight (25-29.9) or obese (>30). The primary outcome of inducible-VT occurred in 42.7%, 21.5% and 21% of normal weight, overweight and obese patients respectively (p < 0.001). When adjusting for ejection-fraction, hypertension and triple-vessel-...

Early and long-term outcomes after manual and remote magnetic navigation-guided catheter ablation for ventricular tachycardia

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, May 1, 2018

Remote magnetic navigation (RMN) is a safe and effective means of performing ventricular tachycar... more Remote magnetic navigation (RMN) is a safe and effective means of performing ventricular tachycardia (VT) ablation. It may have advantages over manual catheter ablation due to ease of manoeuvrability and catheter stability. We sought to compare the safety and efficacy of RMN vs. manual VT ablation. Retrospective study of procedural outcomes of 139 consecutive VT ablation procedures (69 RMN, 70 manual ablation) in 113 patients between 2009 and 2015 was performed. Remote magnetic navigation was associated with overall higher acute procedural success (80% vs. 60%, P = 0.01), with a trend to fewer major complications (3% vs. 9% P = 0.09). Seventy-nine patients were followed up for a median of 17.0 [interquartile range (IQR) 3.0-41.0] months for the RMN group and 15.5 (IQR 6.5-30.0) months for manual ablation group. In the ischaemic cardiomyopathy subgroup, RMN was associated with longer survival from the composite endpoint of VT recurrence leading to defibrillator shock, re-hospitalizat...

Influence of Intramyocardial Adipose Tissue on the Accuracy of Endocardial Contact Mapping of the Chronic Myocardial Infarction Substrate

Circulation. Arrhythmia and electrophysiology, 2017

Recent studies have demonstrated that intramyocardial adipose tissue (IMAT) may contribute to ven... more Recent studies have demonstrated that intramyocardial adipose tissue (IMAT) may contribute to ventricular electrophysiological remodeling in patients with chronic myocardial infarction. Using an ovine model of myocardial infarction, we aimed to determine the influence of IMAT on scar tissue identification during endocardial contact mapping and optimal voltage-based mapping criteria for defining IMAT dense regions. In 7 sheep, left ventricular endocardial and transmural mapping was performed 84 weeks (15-111 weeks) post-myocardial infarction. Spearman rank correlation coefficient was used to assess the relationship between endocardial contact electrogram amplitude and histological composition of myocardium. Receiver operator characteristic curves were used to derive optimal electrogram thresholds for IMAT delineation during endocardial mapping and to describe the use of endocardial mapping for delineation of IMAT dense regions within scar. Endocardial electrogram amplitude correlated...

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Early and Long-Term Outcomes After Manual and Remote Magnetic Navigation Guided Ventricular Tachycardia Ablation

Heart, Lung and Circulation

The Use of Unipolar Endocardial Contact Mapping to Detect the Presence of Intramyocardial Adipose Tissue in the Chronic Myocardial Infarction Substrate

Heart, Lung and Circulation

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Normal BMI is a Significant Independent Predictor of Spontaneously Occurring Ventricular Arrhythmias and Mortality in Patients with Myocardial Infarction, Left Ventricular Dysfunction and ICD Implantation

Heart, Lung and Circulation

Slow Pathway Radiofrequency Ablation Using Magnetic Navigation: A Description of Technique and Retrospective Case Analysis

Heart, lung & circulation, Jan 21, 2017

The Magnetic Navigation System (MNS) catheter was shown to be stable in the presence of significa... more The Magnetic Navigation System (MNS) catheter was shown to be stable in the presence of significant cardiac wall motion and delivered more effective lesions compared to manual control. This stability could potentially make AV junctional reentrant tachycardia (AVNRT) ablation safer. The aim of this study is to describe the method of mapping and ablation of AVNRT with MNS and 3-D electro-anatomical mapping system (CARTO, Biosense Webster, Diamond bar, CA, USA) anatomical mapping, with a view to improve the safety of ablation. The method of precise mapping and ablation with MNS is described. Consecutive AVNRT cases (N=30) from 2012 January to 2015 November, in which magnetic navigation was used, are analysed. Ablation was successful in 27 (90%) out of 30 patients. In three cases, ablation was abandoned due to the proximity of the three-dimensional His image to the potential ablation site. No complications, including AV nodal injury, occurred. The distance from the nearest His position ...

Five seconds of 50–60 W radio frequency atrial ablations were transmural and safe: anin vitromechanistic assessment and force-controlledin vivovalidation

Europace, 2016

Longer procedural time is associated with complications in radiofrequency atrial fibrillation abl... more Longer procedural time is associated with complications in radiofrequency atrial fibrillation ablation. We sought to reduce ablation time and thereby potentially reduce complications. The aim was to compare the dimensions and complications of 40 W/30 s setting to that of high-power ablations (50-80 W) for 5 s in the in vitro and in vivo models. In vitro ablations-40 W/30 s were compared with 40-80 W powers for 5 s. In vivo ablations-40 W/30 s were compared with 50-80 W powers for 5 s. All in vivo ablations were performed with 10 g contact force and 30 mL/min irrigation rate. Steam pops and depth of lung lesions identified post-mortem were noted as complications. A total of 72 lesions on the non-trabeculated part of right atrium were performed in 10 Ovine. All in vitro ablations except for the 40 W/5 s setting achieved the critical lesion depth of 2 mm. For in vivo ablations, all lesions were transmural, and the lesion depths for the settings of 40 W/30 s, 50 W/5 s, 60 W/5 s, 70 W/5 s, and 80 W/5 s were 2.2 ± 0.5, 2.3 ± 0.5, 2.1 ± 0.4, 2.0 ± 0.3, and 2.3 ± 0.7 mm, respectively. The lesion depths of short-duration ablations were similar to that of the conventional ablation. Steam pops occurred in the ablation settings of 40 W/30 s and 80 W/5 s in 8 and 11% of ablations, respectively. Complications were absent in short-duration ablations of 50 and 60 W. High-power, short-duration atrial ablation was as safe and effective as the conventional ablation. Compared with the conventional 40 W/30 s setting, 50 and 60 W ablation for 5 s achieved transmurality and had fewer complications.