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Selected Abstracts

Title: Septal Dyskinesia and Global Left Ventricular Dysfunction in PediatricWolff-Parkinson-White Syndrome with Septal Accessory Pathway

Introduction: Echocardiographic studies have shown that some patients with Wolff-Parkinson-White (WPW) syndrome have myocardial dyskinesia in the segments precociously activated by an accessory pathway (AP). The aim of the present study was to determine the extent to which the AP contributes to global left ventricular (LV) dysfunction.
Methods: Electrophysiological and echocardiographic data from 62 children with WPW (age at diagnosis = 5.9 ± 4.2 years) were retrospectively analyzed.
Results: The left ventricular ejection fraction (LVEF) of patients with septal APs (53 ± 11%) was significantly lower than that of patients with right (62 ± 5%) or left (61 ± 4%) APs (P = 0.001). Compared to patients with normal septal motion (n = 56), patients with septal dyskinesia (n = 6) had a reduced LVEF (61 ± 4% and 42 ± 5%, respectively) and an increased LV end diastolic dimension (P < 0.001 for both comparisons). Multivariate analysis identified septal dyskinesia as the only significant risk factor for reduced LVEF. All 6 patients with septal dyskinesia had right septal APs, and a preexcited QRS duration that was longer than that of patients with normal septal motion (140 ± 18 ms and 113 ± 32 ms, respectively;
P = 0.045). After RFA there were improvements in both intraventricular dyssynchrony (septal-to-posterior wall motion delay, from154±91 ms to 33±17 ms) and interventricular septal thinning (from3.0±0.5mm to 5.3 ± 2.6 mm), and a significant increase in LVEF (from 42 ± 5% to 67 ± 8%; P = 0.001).
Conclusion: The dyskinetic segment activated by a right septal AP in WPW syndrome may lead to ventricular dilation and dysfunction. RFA produced mechanical resynchronization, reverse remodeling, and improvements in LV function. (J Cardiovasc Electrophysiol, Vol. 21, pp. 290-295, March 2010)

Title: Antiarrhythmics After Ablation of Atrial Fibrillation (5A Study)

Roux et al (Circulation 2009;120:1036-1040, PMID 19738139) evaluated if empirical antiarrhythmic drug (AAD) therapy for 6 weeks after atrial fibrillation (AF) ablation reduced atrial arrhythmias. Among 110 consecutive paroxysmal AF patients undergoing ablation randomized to AAD or no AAD for the first 6 weeks, the primary end-point was a composite of (1) atrial arrhythmia _24 hours, (2) atrial arrhythmias requiring hospitalization, cardioversion, or initiation or change of AAD, and (3) intolerance of AAD requiring cessation. Fifty-three patients were randomized to AAD and 57 to no AAD. Fewer patients reached the primary end-point in the AAD group than the no-AAD group (19% vs 42%, P _ .005). Fewer events occurred in the AAD group (13% vs 28%, P_.05) when end-points of AF_24 hours, arrhythmia related hospitalization, or electrical cardioversion were compared. The authors conclude that AAD treatment for the first 6 weeks after AF ablation is well tolerated and reduces the incidence of
clinically significant atrial arrhythmias and the need for cardioversion or hospitalization.

Title: Long-Term Outcome Associated with Early Repolarization on Electrocardiography.

Background :Early repolarization, which is characterized by an elevation of the QRS-ST junction (J point) in leads other than V1 through V3 on 12-lead electrocardiography, has been associated with vulnerability to ventricular fibrillation, but little is known about the prognostic significance of this pattern in the general population.
Methods :We assessed the prevalence and prognostic significance of early repolarization on 12-lead electrocardiography in a community-based general population of 10,864 middle- aged subjects (mean [±SD] age, 44±8 years). The primary end point was death from cardiac causes, and secondary end points were death from any cause and death from arrhythmia during a mean follow-up of 30±11 years. Early repolarization was stratified according to the degree of J-point elevation (≥0.1 mV or >0.2 mV) in either inferior or lateral leads.
Results: The early-repolarization pattern of 0.1 mV or more was present in 630 subjects (5.8%): 384 (3.5%) in inferior leads and 262 (2.4%) in lateral leads, with elevations in both leads in 16 subjects (0.1%). J-point elevation of at least 0.1 mV in inferior leads was associated with an increased risk of death from cardiac causes (adjusted relative risk, 1.28; 95% confidence interval [CI], 1.04 to 1.59; P = 0.03); 36 subjects (0.3%) with J-point elevation of more than 0.2 mV in inferior leads had a markedly elevated risk of death from cardiac causes (adjusted relative risk, 2.98; 95% CI, 1.85 to 4.92; P<0.001) and from arrhythmia (adjusted relative risk, 2.92; 95% CI, 1.45 to 5.89; P = 0.01). Other electrocardiographic risk markers, such as a prolonged QT interval corrected for heart rate (P = 0.03) and left ventricular hypertrophy (P = 0.004), were weaker predictors of the primary end point.
Conclusions: An early-repolarization pattern in the inferior leads of a standard electrocardiogram is associated with an increased risk of death from cardiac causes in middle-aged subjects. N Engl J Med

Title: Introducing a new entity: chemotherapy-induced arrhythmia

The relationship between chemotherapy and arrhythmias has not been well established. We reviewed the existing literature to better understand this connection. We reviewed published reports on chemotherapy-induced arrhythmias in English using the PubMed/Medline and OVID databases from 1950 onwards as well as lateral references. Arrhythmias were reported as a side effect of many chemotherapeutic drugs. Anthracyclines are associated with atrial fibrillation (AF) at a rate of 2-10%, but rarely with ventricular tachycardia (VT)/fibrillation. Taxol and other antimicrotubular drugs are safe in terms of pro-arrhythmic side effects and do not cause any consistent rhythm abnormalities. Arrhythmias induced by 5-fluorouracil, including VT, are mostly ischaemic in origin and usually occur in the context of coronary spasm produced by this drug. Cisplatin--particularly with intrapericardial use--is associated with a very high rate of AF (12-32%). Melphalan is associated with AF in 7-12% of cases, but it does not appear to cause VT. Interleukin-2 is linked to frequent arrhythmia, mostly AF. We summarized the available data on chemotherapy-induced arrhythmia, particularly AF and VT. Studies with prospective data collection and thorough analyses are needed to establish a causal relationship between certain anticancer drugs and arrhythmia.
Europace dec2009

Title: Meta-Analysis of Randomized Trials on the Efficacy of Posterior Pericardiotomy in Preventing Atrial Fibrillation After Coronary Artery Bypass Surgery

This meta-analysis study evaluated the efficacy of a posterior pericardiotomy in preventing AF and supraventricular arrhythmias after coronary artery bypass grafting (CABG).
The authors found 6 prospective, randomized studies reporting on postoperative AF in 763 patients after undergoing a CABG. The cumulative incidence of AF was 10.8% in the posterior pericardiotomy group and 28.1% in the control group. Supraventricular arrhythmias occurred in 13.8% of the patients in the posterior pericardiotomy group and 35.4% in the control group. Early pericardial effusions (6.9% vs 46.2%) and late pericardial effusions were significantly less frequent in the posterior pericardiotomy group. Pleural effusions (22.2% vs 17.1%) and pulmonary complications (3.6% vs 2.5%) were only slightly more frequent in the posterior pericardiotomy group.
Conclusion: A posterior pericardiotomy seems to reduce significantly the incidence of postoperativeAF and supraventricular arrhythmias after undergoing a CABG. The marked reduction in the postoperative pericardial effusions after a posterior pericardiotomy suggests that pericardial effusions may be a main trigger involved in the development of AF after cardiac surgery.
JCE nov 2009

Title: Does Left Atrial Volume and Pulmonary Venous Anatomy Predict the Outcome of Catheter Ablation of Atrial Fibrillation?

Introduction: Preprocedural factors may be helpful in selecting patients with atrial fibrillation (AF) for treatment with catheter ablation and in making an assumption regarding their prognosis. The aims of this study were to investigate whether left atrial (LA) volume and pulmonary venous (PV) anatomy, evaluated by computed tomography (CT) prior to ablation, will predict AF recurrence following catheter ablation.
Methods and Results: We included 146 patients (mean age 57 ± 11 years, 83% male) with symptomatic AF (55% paroxysmal, 18% persistent, 27% long-standing persistent). All patients underwent CT scanning prior to catheter ablation to evaluate LA volume and PV anatomy. Circumferential PV isolation was performed guided by Cartomerge electroanatomical mapping. The outcome was defined as complete success, improvement, or failure. After a mean follow-up of 19 ±7 months, complete success was achieved in 59 patients (40%), and 38 patients (26%) demonstrated improvement. LA volume was found to be an independent predictor of AF recurrence with an adjusted OR of 1.14 for every 10-mL increase in volume (95% CI 1.00-1.29, P = 0.047). PV variations were equally distributed among the different outcomes of the ablation procedure, and therefore univariate analysis did not identify PV anatomy as a predictor of outcome.
Conclusion: LA volume is an independent predictor of AF recurrence after catheter ablation. Additionally, PV anatomy did not have any effect on the outcome. These findings suggest that an assessment of LA volume may be incorporated into the preprocedural evaluation of patients being considered for AF ablation. (J Cardiovasc Electrophysiol, Vol. 20, pp. 1005-1010, September 2009)

Title: Outpatient Electrical Cardioversion of Atrial Fibrillation: 8 Years' Experience. Analysis of Shock-Related Arrhythmias

Background: Outpatient electrical cardioversion (EC) of atrial fibrillation is currently the standard of care. Shock-related arrhythmiasmay be particularly deleterious in this setting. Preoperative identification of high-risk patients may be very useful.
Methods: A retrospective analysis was made of 543 consecutive elective EC procedures in 457 outpatients over an 8-year period in a university cardiological institute. The protocol included adequate anticoagulation, intravenous anesthesia, direct current shock, and a direct observation after a shock to detect procedure-related complications. No patients were excluded due to severity of pathology or comorbidities. Clinical characteristics, energy delivered, medications, arrhythmic phenomena, and predictors of success and complications were analyzed.
Results: Of 543 ECs performed, 88.2% restored sinus rhythm, which persisted at discharge in 83.2%. No anesthesia-related complications were detected. No thromboembolic complications were detected. Use of a biphasic cardioverter was the only predictor of success (P = 0.0001). The bradyarrhythmic complication rate was 1.5%. No ventricular arrhythmic events were detected. Atrial flutter was present in five of eight patients who developed complications versus 44 of 535 patients who had no complications (P < 0.0005), and prosthetic heart valves in four of eight complicated versus 40 of 535 uncomplicated cases (P = 0.0044).
The combination of atrial flutter and prosthetic heart valve was found in four of eight complicated versus 11 of 535 uncomplicated cases (P < 0.0005).
Conclusion: Shock-related arrhythmias are essentially bradyarrhythmias. Atrial flutter and previous cardiac surgery identify a subgroup of patients at high risk of postshock bradyarrhythmic complications.
(PACE 2009; 32:1152-1158)

Title: Selecting the Transthoracic Defibrillation Shock Directional Vector Based on VF Amplitude Improves Shock Success

Introduction: Termination of ventricular fibrillation (VF) by a defibrillating shock is more likely to occur when the VF amplitude is larger. We hypothesized that a defibrillation shock would achieve higher success if the shock vector was oriented along the largest of the VF amplitudes measured simultaneously in 3 orthogonal ECG leads, and that this axis could be determined near-instantaneously in real time.
Methods and Results: In 9 closed-chest anesthetized swine, a new directional defibrillation (DD) device was used to simultaneously measure the VF peak amplitudes displayed by 3 orthogonal pairs of defibrillation electrodes: anterior-posterior, lateral-lateral, and superior-inferior. Four shocks at each of 3 energy levels (30 Joules [J], 50 J, and 100 J) were delivered through the electrode pair measuring the largest (LA) and smallest (SA) VF peak amplitude at the time of the shock. The odds of shock success (VF termination followed by a perfusing rhythm) were 5 times more likely when shocks were delivered from the LA electrodes than the SA electrodes (odds ratio 5.10, 95% CI: 1.39, 18.79). At the intermediate energy level of 50 J, shocks delivered through the LA electrode pairs had an almost 9 times higher odds of shock success than 50 J shocks delivered through the SA electrode pairs (68.3% vs 18.9%, P = 0.002) (odds ratio 8.94, 95% CI: 2.59, 30.82). Transthoracic impedance and current did not differ for shocks delivered in the LA versus SA groups.
Conclusion: Choosing the defibrillation directional vector based on the largest VF amplitude improved
shock success. (J Cardiovasc Electrophysiol, Vol. 20, pp. 1032-1038, September 2009)

Title: Efficacy of Antiarrhythmic Drugs in Arrhythmogenic Right Ventricular Cardiomyopathy

A Report From the North American ARVC Registry
Objectives This study sought to examine the efficacy of empiric antiarrhythmic drugs in a rigorously characterized cohort of arrhythmogenic right ventricular cardiomyopathy (ARVC) patients.
Background Antiarrhythmic drugs are important in protecting against ventricular arrhythmias in ARVC, but no studies have provided data in a group rigorously screened for the disease.
Methods Antiarrhythmic medicines were examined in all subjects with implantable cardioverter-defibrillators (ICDs) enrolled in the North American ARVC Registry. A Cox proportional hazards model was used to account for time on each drug, and a hierarchical analysis was performed for repeated measures within individuals.
Results Ninety-five patients were studied, with a mean follow-up of 480 _ 389 days. Fifty-eight (61%) received betablockers, and these medicines were not associated with an increased or decreased risk of ventricular arrhythmias. Sotalol was associated with a greater risk of any clinically relevant ventricular arrhythmia as defined by sustained ventricular tachycardia or ICD therapy (hazard ratio [HR]: 2.55, 95% confidence interval [CI]: 1.02 to 6.39, p _ 0.045), but this was not statistically significant after adjusting for potential confounders. An increased risk of any ICD shock and first clinically relevant ventricular arrhythmia while on sotalol remained significant after multivariable adjustment. Those on amiodarone (n _ 10) had a significantly lower risk of any clinically relevant ventricular arrhythmia (HR: 0.25, 95% CI: 0.07 to 0.95, p _ 0.041), a finding that remained significant after multivariable adjustment.
Conclusions In a cohort of well-characterized ARVC subjects, neither beta-blockers nor sotalol seemed to be protective. Evidence from a small number of patients suggests that amiodarone has superior efficacy in preventing ventricular arrhythmias. (J Am Coll Cardiol 2009;54:609-15) © 2009 by the American College of Cardiology Foundation

Title: Complications of Atrial Fibrillation Ablation in a High-Volume Center in 1,000 Procedures: Still Cause for Concern?

introduction: Catheter ablation is potentially curative treatment for atrial fibrillation (AF). However, complications are more frequent and more severe compared with other ablation procedures. We investigated the complication rate in 1,000 AF ablation procedures in a high-volume center and examined possible risk factors.
Methods and Results: One thousand consecutive circumferential pulmonary vein radiofrequency ablations were performed for symptomatic, drug-refractory AF. Major complications were defined as the ones that were life threatening, caused permanent harm, and required intervention or prolonged hospitalization. Thirty-nine (3.9%) major periprocedural complications were observed. There was no death immediately associated with the procedure. However, there were 2 deaths (0.2%) of unclear cause, 14 days and 4 weeks
after ablation. The most common complications were tamponade (1.3%), treated mainly by percutaneous drainage, and vascular complications (1.1%). There were also 4 thromboembolic events (0.4%): 3 nonfatal strokes and one transient ischemic attack. Importantly, 2 cases (0.2%) of atrial-esophageal fistula and 2 cases (0.2%) of endocarditis were observed. Factors associated with an increased complication risk were age ≥75 years (hazard ratio 3.977, P = 0.022) and congestive heart failure (hazard ratio 5.174, P = 0.001).
Conclusion: AF ablation still has a considerable number of major complications that may be life threatening or may lead to severe residues. Atrial-esophageal fistula is still observed despite continuous systematic methods to prevent it. Stroke, tamponade, and vascular complications are the most frequent major complications. However, in most patients treatment can be conservative and results in complete recovery. Advanced age and congestive heart failure seem to be associated with an increased risk of complications. (J Cardiovasc Electrophysiol, Vol. 20, pp. 1014-1019, September 2009)

Title: AF in Acute MI

Background: Atrial fibrillation (AF) is associated with increased mortality and a higher complication rate postmyocardial infarction (MI), but the exact mechanisms are unknown. We investigated whether AF predisposes to ventricular arrhythmia in postmyocardial infarct patients, thereby accounting for increased mortality.

Methods: Five hundred consecutive patients admitted to our coronary care unit with acute MI were monitored for in-hospital arrhythmias. Detailed information was also compiled on past history, co-morbidities, electrolyte disturbances, drug therapies, and ejection fraction. Mortality data were collected for an average of 5.5 years.

Results: The results have shown that the incidence of ventricular fibrillation (VF) is much greater in patients presenting with AF (P = 0.03) and multivariate analysis has shown that AF is independently associated with the development of VF. This association occurs principally in patients who are admitted with AF (P = 0.01) rather than those who develop it during their admission, although these patients are also at mildly increased risk. The increased incidence of VF does account for increased mortality in the AF patients but does not explain all of their excess risk. There was no association between AF and ventricular tachycardia (VT); P = 0.50.

Conclusions: In conclusion, AF on admission to the hospital with acute MI is associated with an increased risk of VF and subsequent mortality. (PACE 2008; 31:1612-1619)

Title: Epsilon Wave in ARVD

Background: Epsilon wave is a major criteria for arrhythmogenic right ventricular (RV) dysplasia/ cardiomyopathy (ARVD/C). We sought to study systematically characteristics of Epsilon wave in ARVD/C patients from the southern Chinese population.

Methods: The population included 49 patients with ARVD/C meeting the diagnostic criteria. They were analyzed for the value of different electrocardiogram (ECG) criteria including Epsilon wave, the ones of 24-hour Holter recording, signal-averaged ECG, and echocardiography to learn the correlation between Epsilon wave and other variability with the use of nonparametric test. A probability value of 0.05 was considered significantly different.

Results: It shown that the detection rate of Epsilon wave was significantly higher in probands (65%) than involved family members (22%), P = 0.03. In the conventional as well as Fontaine leads, its detection rate were 18 (37%) and 28 (57%), respectively. The prevalence of diffuse right ventricle involvement, T-wave inversion and signal-averaged ECG are significantly different between the ARVD/C patients with Epsilon wave and without Epsilon wave.

Conclusion: It is significantly correlated between Epsilon wave and the progressive ARVD/C. (PACE 2009; 32:59-63)

Title: Catheter Ablation Versus Antiarrhythmic Drugs in AF

Background--The mainstay of treatment for atrial fibrillation (AF) remains pharmacological; however, catheter ablation has increasingly been used over the last decade. The relative merits of each strategy have not been extensively studied.

Methods and Results--We conducted a randomized multicenter comparison of these 2 treatment strategies in patients with paroxysmal AF resistant to at least 1 antiarrhythmic drug. The primary end point was absence of recurrent AF between months 3 and 12, absence of recurrent AF after up to 3 ablation procedures, or changes in antiarrhythmic drugs during the first 3 months. Ablation consisted of pulmonary vein isolation in all cases, whereas additional extrapulmonary vein lesions were at the discretion of the physician. Crossover was permitted at 3 months in case of failure. Echocardiographic data, symptom score, exercise capacity, quality of life, and AF burden were evaluated at 3, 6, and 12 months by the supervising committee. Of 149 eligible patients, 112 (18 women [16%]; age, 51.111.1 years) were enrolled and randomized to ablation (n53) or "new" antiarrhythmic drugs alone or in combination (n59). Crossover from the antiarrhythmic drugs and ablation groups occurred in 37 (63%) and 5 patients (9%), respectively (P0.0001). At the 1-year follow-up, 13 of 55 patients (23%) and 46 of 52 patients (89%) had no recurrence of AF in the antiarrhythmic drug and ablation groups, respectively (P0.0001). Symptom score, exercise capacity, and quality of life were significantly higher in the ablation group.

Conclusion--This randomized multicenter study demonstrates the superiority of catheter ablation over antiarrhythmic drugs in patients with AF with regard to maintenance of sinus rhythm and improvement in symptoms, exercise capacity, and quality of life. (Circulation. 2008;118:2498-2505.)

Title: VT ablation after MI

Background--Recurrent ventricular tachycardia (VT) is an important cause of mortality and morbidity late after myocardial infarction. With frequent use of implantable cardioverter-defibrillators, these VTs are often poorly defined and not tolerated for mapping, factors previously viewed as relative contraindications to ablation. This observational multicenter study assessed the outcome of VT ablation with a saline-irrigated catheter combined with an electroanatomic mapping system.

Methods and Results--Two hundred thirty-one patients (median LV ejection fraction, 0.25; heart failure in 62%) with recurrent episodes of monomorphic VT (median, 11 in the preceding 6 months) caused by prior myocardial infarction were enrolled. All inducible monomorphic VTs with a rate approximating or slower than any spontaneous VTs were targeted for ablation guided by electroanatomic mapping during sinus rhythm and/or VT. Patients were not excluded for multiple VTs (median, 3 per patient) or unmappable VT (present in 69% of patients). Ablation abolished all inducible VTs in 49% of patients. The primary end point of freedom from recurrent incessant VT or intermittent VT after 6 months of follow-up was achieved for 123 patients (53%). In 142 patients with implantable cardioverter-defibrillators before and after ablation for intermittent VT who survived 6 months, VT episodes were reduced from a median of 11.5 to 0 (P0.0001). The 1-year mortality rate was 18%, with 72.5% of deaths attributed to ventricular arrhythmias or heart failure. The procedure mortality rate was 3%, with no strokes.

Conclusions--Catheter ablation is a reasonable option to reduce episodes of recurrent VT in patients with prior myocardial infarction, even when multiple and/or unmappable VTs are present. This population remains at high risk for death, warranting surveillance and further study. (Circulation. 2008;118:2773-2782.)

Title: Acacetin, a Natural Flavone, Selectively Inhibits Human Atrial Repolarization Potassium Currents and Prevents Atrial Fibrillation in Dogs

Background--The development of atrium-selective antiarrhythmic agents is a current strategy for inhibiting atrial fibrillation (AF). The present study investigated whether the natural flavone acacetin from the traditional Chinese medicine Xuelianhua would be an atrium-selective anti-AF agent.

Methods and Results--The effects of acacetin on human atrial ultrarapid delayed rectifier K_ current (IKur) and other cardiac ionic currents were studied with a whole-cell patch technique. Acacetin suppressed IKur and the transient outward K_ current (IC50 3.2 and 9.2 _mol/L, respectively) and prolonged action potential duration in human atrial myocytes. The compound blocked the acetylcholine-activated K_ current; however, it had no effect on the Na_ current, L-type Ca2_ current, or inward-rectifier K_ current in guinea pig cardiac myocytes. Although acacetin caused a weak reduction in the hERG and hKCNQ1/hKCNE1 channels stably expressed in HEK 293 cells, it did not prolong the corrected QT interval in rabbit hearts. In anesthetized dogs, acacetin (5 mg/kg) prolonged the atrial effective refractory period in both the right and left atria 1 to 4 hours after intraduodenal administration without prolongation of the corrected QT interval, whereas sotalol at 5 mg/kg prolonged both the atrial effective refractory period and the corrected QT interval. Acacetin prevented AF induction at doses of 2.5 mg/kg (50%), 5 mg/kg (85.7%), and 10 mg/kg (85.7%). Sotalol 5 mg/kg also prevented AF induction (60%).

Conclusions--The present study demonstrates that the natural compound acacetin is an atrium-selective agent that prolongs the atrial effective refractory period without prolonging the corrected QT interval and effectively prevents AF in anesthetized dogs after intraduodenal administration. These results indicate that oral acacetin is a promising atrium-selective agent for the treatment of AF. (Circulation. 2008;117:2449-2457

Title: Long-term endurance sport practice increases the incidence of lone atrial fibrillation in men: a follow-up study

Aims: The aim of this study is to determine the incidence of lone atrial fibrillation (LAF) in males according to sport practice and to identify possible clinical markers related to LAF among marathon runners.

Methods and results :A retrospective cohort study was designed. A group of marathon runners (n ¼ 252) and a population-based sample of sedentary men (n ¼ 305) recruited in 1990-92 and 1994-96, respectively, were contacted in 2002-03 and invited to attend an outpatient clinic to identify suggestive symptoms of having experienced an arrhythmia requiring medical attention. In those with suggestive symptoms of atrial fibrillation, medical records were reviewed. Finally, LAF was diagnosed on the basis of the presence of atrial fibrillation in an electrocardiographic recording. In the group of marathon runners, an echocardiogram was performed at inclusion and at the end of the study. The annual incidence rate of LAF among marathon runners and sedentary men was 0.43/100 and 0.11/100, respectively. Endurance sport practice was associated with a higher risk of incident LAF in the multivariate age- and blood pressure-adjusted Cox regression models (hazard ratio ¼ 8.80; 95% confidence interval: (1.26-61.29). In the group of marathon runners, left atrial inferosuperior diameter and left atrial volume were both associated with a higher risk of incident LAF.

Conclusion: Long-term endurance sport practice is associated with a higher risk of symptomatic LAF in men. This risk is associated with a larger left atrial inferosuperior diameter and volume in physically active subjects.

Title: A quantitative assessment of T-wave morphology in LQT1, LQT2, and healthy individuals based on Holter recording technology

BACKGROUND; The clinical course and the precipitating risk factors in the congenital long QT syndrome (LQTS) are genotype specific.

OBJECTIVES: The goal of this study was to develop a computer algorithm allowing for electrocardiogram (ECG)-based identification and differentiation of LQT1 and LQT2 carriers.

METHODS: Twelve-lead ECG Holter monitor recordings were acquired in 49 LQT1 carriers, 25 LQT2 carriers, and 38 healthy subjects as controls. The cardiac beats were clustered based on heart-rate bin method. Scalar and vectorial repolarization parameters were compared for similar heart rates among study groups. The Q to Tpeak (QTpeak), the Tpeak to Tend interval, T-wave magnitude and T-loop morphology were automatically quantified using custom-made algorithms.

RESULTS: QTpeak from lead II and the right slope of the T-wave were the most discriminant parameters for differentiating the 3 groups using prespecified heart rate bin (75.0 to 77.5 beats/min).The predictive model utilizing these scalar parameters was validated using the entire spectrum of heart rates. Both scalar and vectorcardiographic models provided very effective identification of tested subjects in heart rates between 60 and 100 beats/min, whereas they had limited performance during tachycardia and slightly better discrimination in bradycardia. In the 60 to 100 beats/min heart rate range, the best 2-variable model identified correctly 89% of healthy subjects, 84% of LQT1 carriers, and 92% of LQT2 carriers. A model including 3 parameters based purely on scalar ECG parameters could correctly identify 90% of the population (89% of healthy subjects, 90% of LQT1 carriers, and 92% of LQT2 carriers).

CONCLUSION: Automatic algorithm quantifying T-wave morphology discriminates LQT1 and LQT2 carriers and healthy subjects with high accuracy. Such computerized  ECG methodology  could assist physicians evaluating subjects suspected for LQTS.

 

Title: New algorithm using only lead aVR for differential diagnosis of wide QRS complex tachycardia

BACKGROUND: We recently reported an ECG algorithm for differential diagnosis of regular wide QRS complex tachycardias that was superior to the Brugada algorithm.

OBJECTIVE: The purpose of this study was to further simplify the algorithm by omitting the complicated morphologic criteria and restricting the analysis to lead aVR.

METHODS: In this study, 483 wide QRS complex tachycardias [351 ventricular tachycardias (VTs), 112 supraventricular tachycardias (SVTs), 20 preexcited tachycardias] from 313 patients with proven diagnoses were prospectively analyzed by two of the authors blinded to the diagnosis. Lead aVR was analyzed for (1) presence of an initial R wave, (2) width of an initial r or q wave 40 ms, (3) notching on the initial downstroke of a predominantly negative QRS complex, and (4) ventricular activation-velocity ratio (vi/vt),the vertical excursion (in millivolts) recorded during the initial (vi) and terminal (vt) 40 ms of the QRS complex. When any of criteria 1 to 3 was present, VT was diagnosed; when absent, the next criterion was analyzed. In step 4, vi/vt 1 suggested SVT, and vi/vt 1 suggested VT.

RESULTS: The accuracy of the new aVR algorithm and our previous algorithm was superior to that of the Brugada algorithm (P .002 and P .007, respectively). The aVR algorithm and our previous algorithm had greater sensitivity (P .001 and P .001, respectively) and negative predictive value for diagnosing VT and greater specificity (P .001 and P .001, respectively) and positive predictive value for diagnosing SVT compared with the Brugada criteria.

CONCLUSION :The simplified aVR algorithm classified wide QRS complex tachycardias with the same accuracy as standard criteria and our previous algorithm and was superior to the Brugada algorithm.

 

 

Title: Electrocardiographic factors playing a role in ischemic ventricular fibrillation in ST elevation myocardial infarction are related to the culprit artery

BACKGROUND:
Sudden cardiac death caused by ischemic ventricular fibrillation (VF) associated with ST elevation myocardial infarction (STEMI) is one of the most frequent causes of death.

OBJECTIVE:

 We hypothesized that electrocardiographic (ECG) characteristics differ between STEMI patients with and without ischemic VF.

METHODS :
Fifty-five first STEMI patients with at least one 12-lead ECG recorded before ischemic VF were compared with 110 first STEMI patients without ischemic VF. Patients with bundle
branch blocks or high-degree atrioventricular blocks with escape rhythms were not included. ECG measurements were performed manually after scanning the ECG with the most prominent ST deviation into a software environment and magnifying it 4 times.

RESULTS :
Mean age was 57  12 years, and 126 patients were male. No differences were present between the VF and control group regarding baseline, enzymatic, and angiographic data. In
left circumflex artery and right coronary artery myocardial infarction,a longer QRS interval (109  23 ms vs. 91  16 ms, P  .02 and 107  24 ms vs. 93  19, P  .02) was present. In the latter the PR interval (211  64 ms vs. 160  36 ms, P .001) and ST deviation score (3.6  1.0 mV vs. 1.7  1.5 mV, P .001) were also increased. In the left anterior descending artery group no differences in conduction intervals and ST deviation score were present.

CONCLUSION :
Longer PR and QRS intervals in right coronary artery and left circumflex artery MI fit with the perfusion and activation pattern of the atrioventricular node and the ventricular myocardium. Myocardium perfused by the left anterior descending artery is activated earliest, hiding any intraventricular conduction delay within the QRS complex. Intramural slowed conduction could
be a substrate for ischemic VF.