Papers by Lennart Bergfeldt
Läkartidningen, Jan 11, 2006
Pacing and Clinical Electrophysiology, Jun 1, 2005
Hypertrophic cardiomyopathy carries an increased risk for sudden cardiac death. While pacing ther... more Hypertrophic cardiomyopathy carries an increased risk for sudden cardiac death. While pacing therapy reduces the left ventricular outflow tract gradient and improves symptoms in a subgroup of hypertrophic obstructive cardiomyopathy (HOCM) patients, its electrophysiological consequences are unknown and were therefore assessed in this prospective study. Fifteen consecutive HOCM patients were studied and compared with 14 patients without HOCM paced because of sinus bradycardia. ECG intervals were measured before pacemaker implantation and after > or =3 months of DDD pacing in HOCM patients and > or =5 weeks in controls. Both groups showed similar ECG signs of cardiac memory development. In HOCM patients, with baseline QTc 447 +/- 33 ms, cardiac memory development was not associated with any significant changes in ECG intervals. In contrast, baseline repolarization in control patients was significantly prolonged by 6% (QTc 429 +/- 33 vs 454 +/- 46 ms; P < 0.05). Furthermore, in HOCM patients repolarization was 7% shorter during DDD pacing compared to sinus rhythm (JTc 329 +/- 25 vs 353 +/- 21 ms; P < 0.05), despite a significantly prolonged ventricular activation time (QRS duration 155 +/- 16 vs 91 +/- 9 ms; P < 0.01). Importantly, the development of cardiac memory-induced different repolarization responses depending on baseline structure and electrophysiology. In HOCM patients repolarization was shorter during right ventricular apical pacing than during normal activation despite prolonged activation time.
Medicine and Science in Sports and Exercise, Jul 1, 2014
This study aimed to assess the prevalence and patterns of early repolarization (ER) in middle-age... more This study aimed to assess the prevalence and patterns of early repolarization (ER) in middle-age long-distance runners, its relation to cardiac structure and function, and its response to strenuous physical activity. Male first-time cross-country race participants >45 yr were assessed pre- and postrace by medical history and physical examination, 12-lead ECG, vectorcardiography, blood tests, and echocardiography. ER was defined either as ST elevation or J wave and categorized according to localization and morphology. One hundred and fifty-one subjects (50 ± 5 yr) were evaluated before the race, and 47 subjects were evaluated after the race. Altogether, 67 subjects (44%) had ER. Subjects with versus without ER had a lower resting HR (56 ± 8 vs 69 ± 9 bpm, P = 0.02), lower body mass index (24 ± 2 vs 25 ± 3 kg·m(-2), P < 0.001), higher training volume (3.0 ± 2.6 vs 2.1 ± 2.7 h·wk(-1), P = 0.03), and faster 30-km running times (194 ± 28 vs 208 ± 31 min, P = 0.01). Vectorcardiography parameters in subjects with ER showed more repolarization heterogeneity: vector gradient (QRS-T(area)) (120 ± 25 vs 92 ± 29 μVs, P < 0.001), T(area) (105 ± 18 vs 73 ± 23 μVs, P < 0.001), and T(amplitude) (0.63 ± 0.13 vs 0.53 ± 0.16 mm, P < 0.001); these parameters were inversely related to HR (r = -0.37 to -0.48, P < 0.001). ER disappeared in 15 (75%) of 20 subjects after the race. ER is a common finding in middle-age male runners. This ECG pattern, regardless of morphology and localization, is associated with normal cardiac examinations including noninvasive electrophysiology, features of better physical conditioning, and disappears after strenuous exercise in most cases. These findings support that ER should be regarded as a common and training-related finding also in middle-age physically active men.
American Journal of Cardiology, Nov 1, 1997
This study assesses the incidence of sudden death and classifies the causes of death following ra... more This study assesses the incidence of sudden death and classifies the causes of death following radiofrequency ablation of the atrioventricular (AV) junction. We studied 220 patients with paroxysmal (n = 105) or chronic (n = 115) atrial fibrillation (AF) and a mean age of 64 +/- 12 years. These patients were followed 31 +/- 15 months after radiofrequency ablation of the AV junction and pacemaker implantation. In 86 patients, structural heart disease was identified before the procedure. All patients were traced via the Swedish National Civic Registry and Cause of Death Registry. The cause-of-death was classified according to data from death certificates, autopsy protocols, and medical records. Thirty-one patients (mean age 69 +/- 11 years, 16 men) died 15 +/- 15 months (range 0.2 to 60) after the procedure. There were 6 sudden unexplained deaths, 14 cardiovascular deaths, and 11 deaths from noncardiovascular causes. Eleven patients, all with structural heart disease, died suddenly out of hospital 16 +/- 16 months (range 0.2 to 42) after the procedure. In 6 of these there was no obvious cause of death. Three of these 6 patients underwent autopsy, which showed extensive coronary artery disease (n = 1), severe heart failure (n = 1) and cardiac hypertrophy and dilation (n = 1). The remaining 3 all had depressed left ventricular systolic function and a history of congestive heart failure. Five of the patients who died suddenly from cardiovascular causes had autopsies that revealed acute myocardial infarction (n = 4) and massive pulmonary embolism (n = 1).
Journal of Electrocardiology, 2015
Background: QRS duration and left bundle branch block (LBBB) morphology are used to select patien... more Background: QRS duration and left bundle branch block (LBBB) morphology are used to select patients for cardiac resynchronization therapy (CRT). We investigated whether the area of the QRS complex (QRS AREA) on the 3-dimensional vectorcardiogram (VCG) can improve patient selection. Methods: VCG (Frank orthogonal lead system) was recorded prior to CRT device implantation in 81 consecutive patients. VCG parameters, including QRS AREA , were assessed, and compared to QRS duration and morphology. Three LBBB definitions were used, differing in requirement of mid-QRS notching. Responders to CRT (CRT-R) were defined as patients with ≥ 15% reduction in left ventricular end systolic volume after 6 months of CRT. Results: Fifty-seven patients (70%) were CRT-R. QRS AREA was larger in CRT-R than in CRT nonresponders (140 ± 42 vs 100 ± 40 μVs, p b 0.001) and predicted CRT response better than QRS duration (AUC 0.78 vs 0.62, p = 0.030). With a 98 μVs cutoff value, QRS AREA identified CRT-R with an odds ratio (OR) of 10.2 and a 95% confidence interval (CI) of 3.4 to 31.1. This OR was higher than that for QRS duration N 156 ms (OR = 2.5; 95% CI 0.9 to 6.6), conventional LBBB classification (OR = 5.5; 95% CI 0.9 to 32.4) or LBBB classification according to American guidelines (OR = 4.5; 95% CI 1.6 to 12.6) or Strauss (OR = 10.0; 95% CI 3.2 to 31.1). Conclusion: QRS AREA is an objective electrophysiological predictor of CRT response that performs at least as good as the most refined definition of LBBB. Condensed abstract: In 81 candidates for cardiac resynchronization therapy (CRT) we measured the area of the QRS complex (QRS AREA) using 3-dimensional vectorcardiography. QRS AREA was larger in echocardiographic responders than in non-responders and predicted CRT response better than QRS duration and than simple LBBB criteria. QRS AREA is a promising electrophysiological predictor of CRT response.
Journal of Electrocardiology, Sep 1, 2011
Cardiac memory is known as T-wave inversions and other repolarization changes after a period of a... more Cardiac memory is known as T-wave inversions and other repolarization changes after a period of altered ventricular activation, previously mainly studied in structurally normal hearts. We investigated repolarization changes in failing hearts undergoing cardiac resynchronization therapy (CRT). Electrocardiogram and vectorcardiogram were recorded before and 1 day and 2 weeks after initiation of CRT in 23 patients with heart failure and left bundle-branch block. After 1 day of CRT, the T vector during intrinsic conduction (left bundle-branch block) had rotated toward the direction of the paced QRS vector; T-vector size had increased with further increase after 2 weeks (T-vector amplitude, 889 ± 277 vs 651 ± 225 μV; T area, 169 ± 70 vs 102 ± 39 μVs; P < .01) accompanied by prolonged repolarization (T peak-to-end, 174 ± 34 vs 127 ± 16; QT interval corrected for heart rate, 541 ± 59 vs 493 ± 33 milliseconds; P < .01). Repolarization changes are present in patients with heart failure, although less pronounced compared with after right ventricular pacing in structurally normal hearts.
International Journal of Cardiology, 2006
Journal of Cardiovascular Electrophysiology, 2021
AimsTo assess whether the prevailing rhythm at the time of replying to symptom and health‐related... more AimsTo assess whether the prevailing rhythm at the time of replying to symptom and health‐related quality of life (HR‐QoL) questionnaires impacts the findings.MethodA total of 150 patients from the randomized Catheter Ablation Compared with Pharmacological Therapy for Atrial Fibrillation‐trial, comparing atrial fibrillation (AF) ablation versus drugs, were included. The effect of the prevailing rhythm on the outcome results of the HR‐QoL 36‐Item Short‐Form Health Survey, the symptom severity questionnaire (SSQ), and the European Heart Rhythm Association (EHRA) score for classification of AF‐related symptoms was assessed.ResultsAF as the prevailing rhythm was independently associated with a significantly lower Vitality score; 18.4 points lower (95% confidence interval −32.7 to −4.1, p = .01) compared with sinus rhythm when adjusted for AF burden, median duration of episode, number of episodes, beta‐blocker use, type of AF, and sex. The presence of AF did not affect the General Health...
EP Europace, 2019
Efficacy and safety of dronedarone was shown in the ATHENA trial for paroxysmal or persistent atr... more Efficacy and safety of dronedarone was shown in the ATHENA trial for paroxysmal or persistent atrial fibrillation (AF) patients. Further trials revealed safety concerns in patients with heart failure and permanent AF. This review summarizes insights from recent real-world studies and meta-analyses, including reports on efficacy, with focus on liver safety, mortality risk in patients with paroxysmal/persistent AF, and interactions of dronedarone with direct oral anticoagulants. Reports of rapidly progressing liver failure in dronedarone-prescribed patients in 2011 led to regulatory cautions about potential liver toxicity. Recent real-world evidence suggests dronedarone liver safety profile is similar to other antiarrhythmics and liver toxicity could be equally common with many Class III antiarrhythmics. Dronedarone safety concerns (increased mortality in patients with permanent AF) were raised based on randomized controlled trials (RCT) (ANDROMEDA and PALLAS), but comedication with d...
Läkartidningen, Jan 13, 1995
International Journal of Cardiology, Jun 1, 2013
Pacing induced cardiac memory is an established phenomenon, but following successful WPW ablation... more Pacing induced cardiac memory is an established phenomenon, but following successful WPW ablation, cardiac memory was present on ECG in variable proportions of patients depending on accessory pathway (AP) location. We hypothesized that vectorcardiography (VCG), which is more sensitive than ECG, would show cardiac memory after WPW ablation independent of AP location. Thirty-six patients were followed after successful AP ablation, 11 with overt posteroseptal (PS), 13 with overt left-sided (LS) and 12 with concealed APs (controls). VCGs were recorded the day before and after the procedure, ≥ once/week for 6-8 weeks and after ≥ 3 months. T vector and T-vector loop parameters were analyzed and compared. After ablation of overt APs, there was a correlation between the directions of the preexcited maximum QRS-vector and the post-ablation maximum T-vector, confirming the presence of cardiac memory. Ablation of overt APs was followed by cardiac memory apparent in different directions. Thus, ablation of PS APs was followed by most pronounced changes in T-vector elevation and LS APs with significant changes only in T-vector azimuth. Cardiac memory disappeared within a month in > 80% of cases. Furthermore, T-vector loop morphology changes suggested a period of repolarization heterogeneity immediately after ablation of overt APs. According to VCG analysis cardiac memory was present after ablation of overt APs independent of location as consistently as after ventricular pacing, and disappeared within a similar time frame during normal ventricular activation. In addition, signs of transient repolarization heterogeneity were observed after ablation of overt APs.
Heart Rhythm, Dec 1, 2007
BACKGROUND Right ventricular apical (RVA) pacing induces electrophysiological and structural remo... more BACKGROUND Right ventricular apical (RVA) pacing induces electrophysiological and structural remodeling. Cardiac memory (CM) evolves during the course of pacing and is readily apparent on electrocardiography (ECG) or vectorcardiography (VCG) when normal ventricular activation resumes. OBJECTIVE This study sought to assess ventricular repolarization (VR) changes during pacing and intermittent normal ventricular conduction by ECG and VCG and to determine the temporal and conformational evolution of CM. METHODS Twenty sick sinus patients received a dual-chamber rateadaptive (DDD-R) pacemaker and were paced from the RVA endocardium. The pacemakers were programmed to a short AV delay to maximize ventricular preexcitation. The ECG and VCG were recorded before and 1 day after implantation, and then daily for the first week (n ϭ 6) or weekly for 5 to 8 weeks (n ϭ 14), with the pacemakers temporarily programmed to AAI (normal ventricular activation). RESULTS The first parameters to change were T-vector amplitude, T area , and T peak-T end (T p-e), which decreased within 1 day after initiating pacing. CM became apparent between day 1 and day 3, was fully established after 1 week, and then remained stable. Signs of increased VR heterogeneity were observed as the T loop became more circular (decreased T egenv) and distorted (increased T avplan), which have previously been observed in conditions with increased risk for arrhythmias. Over weeks, VR duration was prolonged (increased QTc). In contrast, during ventricular pacing, a gradual shortening of the repolarization time was observed, suggesting a stabilizing adaptive process. CONCLUSION In sick sinus syndrome patients in whom ventricular pacing is indicated, switching between normal AV conduction and ventricular pacing should be minimized to avoid periods of repolarization instability.
RMD Open, 2019
ObjectivesTo describe electrocardiographic (ECG) development in patients with ankylosing spondyli... more ObjectivesTo describe electrocardiographic (ECG) development in patients with ankylosing spondylitis (AS) and identify associations between baseline characteristics and cardiac conduction disturbances (CCD) at 5-year follow-up.MethodsIn a longitudinal cohort study, 172 patients (54% men, mean age (SD) of 50 (13) years at baseline) with AS underwent ECG, physical examination, questionnaires and laboratory testing at baseline and at 5-year follow-up. Descriptive statistics and univariate and age- and sex-adjusted logistic regression analyses were used. CCD included both atrioventricular and intraventricular blocks.ResultsTwenty-three of the 172 patients (13.4%) had a CCD at follow-up. Eight patients had developed a new CCD and eight had normalised their ECG. In the age- and sex-adjusted analyses, CCD at baseline (OR 24.8, 95% CI 7.3 to 84.5), male sex (OR 6.4, 95% CI 2.0 to 20.8), history of anterior uveitis (OR 4.4, 95% CI 1.3 to 14.5), higher ASDAS-CRP (OR 2.3, 95% CI 1.3 to 4.0), g...
Journal of Electrocardiology, 2020
Background: The spatial peak and mean QRS-T angles are scientifically but not clinically establis... more Background: The spatial peak and mean QRS-T angles are scientifically but not clinically established risk factors for cardiovascular events including cardiac death. The study aims were to compare these angles, assess their association with hypertension (HT) and diabetes mellitus (DM), and explore the relation between the mean QRS-T angle and the ventricular gradient (VG; reflecting electrical heterogeneity), which both are derived from the QRSarea and Tarea vectors. Methods: Altogether 1094 participants (aged 50-65 years, 550 women) from the pilot of the population-based Swedish CArdioPulmonary bioImage Study with Frank vectorcardiographic recordings were included and divided into 5 subgroups: apparently healthy n = 320; HT n = 311; DM n = 33; DM + HT n = 53; miscellaneous conditions n = 377. Abnormal peak and mean QRS-T angles were defined as N95th percentile. Results: Peak QRS-T angles were generally narrower than the mean QRS-T angles; both were narrower in women than in men. Abnormal peak (N124°) and/or mean (N119°) QRS-T angles were found in 73 participants (6.7%). The concordance regarding abnormal versus normal-borderline QRS-T angles was good (Cohen's kappa 0.61). The prevalence of abnormal angles varied from 2.5% in healthy to 21.2% in DM. There was an inverse logarithmical relation between the mean QRS-T angle and the VG. Conclusions: The peak and mean QRS-T angles are not interchangeable but complementary. DM, HT, sex and absence of disease are important determinants of both QRS-T angles. The mean QRS-T angle and the VG relationship is complex. All three VCG derived measures reflect related but differing electrophysiological properties and have potential prognostic value vis-à-vis cardiovascular events.
Annals of Noninvasive Electrocardiology, 2020
The heart rate (HR) corrected QT interval (QTc) is crucial for diagnosis and risk stratification ... more The heart rate (HR) corrected QT interval (QTc) is crucial for diagnosis and risk stratification in the long QT syndrome (LQTS). Although its use has been questioned in some contexts, Bazett's formula has been applied in most diagnostic and prognostic studies in LQTS patients. However, studies on which formula eliminates the inverse relation between QT and HR are lacking in LQTS patients.
Lakartidningen, 2015
Early repolarization defined as antero-lateral ST-segment elevation exists in 1-2 % of the genera... more Early repolarization defined as antero-lateral ST-segment elevation exists in 1-2 % of the general population and has been considered a benign ECG finding for decades. However, early repolarization, defined as infero-lateral J-waves, has in recent studies been associated with an increased - albeit low - risk of sudden and cardiovascular death. This ECG pattern is present in 3-13% of the general population. However, exercise training can induce all types of early repolarization, and the prevalence in the athletic population rises to 20-90%. There is large variability between sports (higher in endurance athletes) and also throughout the season (higher during times of peak fitness). In athletes, early repolarization, regardless of type, is considered benign. In asymptomatic non-athletes, the absolute risk is too low to use this ECG finding in clinical practice. In individuals with J-wave syndrome, on the other hand, ICD implantation should be strongly considered to prevent sudden cardi...
Journal of electrocardiology, Jan 13, 2014
Atrial fibrillation (AF) is the most common form of arrhythmia in humans and is associated with s... more Atrial fibrillation (AF) is the most common form of arrhythmia in humans and is associated with substantial morbidity and mortality. Obesity and diabetes have been linked to myocardial lipotoxicity - a condition where the heart accumulates and produces toxic lipid species. We hypothesized that obesity and diabetes were involved in the pathophysiology of AF by means of promoting a lipotoxic phenotype in atrial muscle, and that AF predicts mortality in cardiac care patients. Our study consists of two parts. The first part is a registry study based on prospective data obtained through the Register of Information and Knowledge about Swedish Heart Intensive Care Admissions (RIKS-HIA) from hospitals in western Sweden. All consecutive patients between 2006 and 2011 admitted to coronary care unit (CCU) with sinus rhythm (SR) or AF were included in the analysis. Multivariate logistic regression and Cox proportional-hazards regression were used to test whether diabetes and obesity were indepe...
BMC Musculoskeletal Disorders, 2013
Background: Cardiac conduction disturbances are common in spondyloarthropathies such as ankylosin... more Background: Cardiac conduction disturbances are common in spondyloarthropathies such as ankylosing spondylitis (AS). Whether their occurrence can be linked to signs and symptoms of rheumatic disease activity is an unsettled issue addressed in this study. Methods: In this cross-sectional study patients with AS according to modified New York criteria but without psoriasis, inflammatory bowel disease, dementia, pregnancy, other severe diseases such as malignancy and difficulties in answering questionnaires were invited; and 210 participated (120 men), mean age 49 years (SD 13; range: 16-77). Questionnaires, physical examination, ECG, and laboratory tests were performed at the same visit. Results: Cardiac conduction disturbances were common and diagnosed in 10-33%, depending on if conservative or less conservative predefined criteria were applied. They consisted mostly of 1 st degree atrio-ventricular block and prolonged QRS duration, but one patient had a pacemaker and 7 more had complete bundle branch blocks. Conduction abnormalities were associated mainly with age, male gender and body weight, and not with laboratory measures of inflammation or with Bath Ankylosing Spondylitis Disease Activity Index. Neither were they associated with the presence of HLA B27, which was found in 87% of all patients; the subtype B270502 dominated in all patients. Conclusions: Cardiac conduction abnormalities are common in AS, but not associated with markers of disease activity or specific B27 subtypes. Even relatively mild conduction system abnormalities might, however, indirectly affect morbidity and mortality.
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Papers by Lennart Bergfeldt