Very late recurrences of atrial fibrillation after pulmonary vein isolation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, accounting for approximately one-third of all hospitalizations from cardiac rhythm disturbances. Over the past decade, catheter ablation (predominantly in the form of pulmonary vein isolation [PVI]) has become an important therapy in the treatment of patients with symptomatic, drug-refractory AF. Despite the improvements in technology, operator experience, and advances in methodology that have led to higher success rates and a reduction in complications, the recurrence rate of AF after PVI is still relatively high. Published studies suggest that approximately 33% to 86% of patients undergoing catheter ablation of AF have freedom from recurrent AF, with 30% to 40% requiring a second procedure. Although most studies looking at the efficacy of PVI are limited by relatively short follow-up, recent data suggest that patients with an initially favorable procedural response may have very late recurrences of AF, even years after PVI. It is likely that the mechanism behind very late recurrences of AF is multifactorial, involving both recurrent pulmonary vein triggers and progressive remodeling of left atrial substrate over time, making it more vulnerable to triggering. These recurrences have important clinical implications in the care of patients, specifically with regard to the increased risk of stroke associated with AF.

Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the task force criteria

BACKGROUND

In 1994, an International Task Force proposed criteria for the clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) that facilitated recognition and interpretation of the frequently nonspecific clinical features of ARVC/D. This enabled confirmatory clinical diagnosis in index cases through exclusion of phenocopies and provided a standard on which clinical research and genetic studies could be based. Structural, histological, electrocardiographic, arrhythmic, and familial features of the disease were incorporated into the criteria, subdivided into major and minor categories according to the specificity of their association with ARVC/D. At that time, clinical experience with ARVC/D was dominated by symptomatic index cases and sudden cardiac death victims-the overt or severe end of the disease spectrum. Consequently, the 1994 criteria were highly specific but lacked sensitivity for early and familial disease.

METHODS AND RESULTS

Revision of the diagnostic criteria provides guidance on the role of emerging diagnostic modalities and advances in the genetics of ARVC/D. The criteria have been modified to incorporate new knowledge and technology to improve diagnostic sensitivity, but with the important requisite of maintaining diagnostic specificity. The approach of classifying structural, histological, electrocardiographic, arrhythmic, and genetic features of the disease as major and minor criteria has been maintained. In this modification of the Task Force criteria, quantitative criteria are proposed and abnormalities are defined on the basis of comparison with normal subject data.

CONCLUSIONS

The present modifications of the Task Force Criteria represent a working framework to improve the diagnosis and management of this condition.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00024505.

Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the Task Force Criteria

BACKGROUND

In 1994, an International Task Force proposed criteria for the clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) that facilitated recognition and interpretation of the frequently nonspecific clinical features of ARVC/D. This enabled confirmatory clinical diagnosis in index cases through exclusion of phenocopies and provided a standard on which clinical research and genetic studies could be based. Structural, histological, electrocardiographic, arrhythmic, and familial features of the disease were incorporated into the criteria, subdivided into major and minor categories according to the specificity of their association with ARVC/D. At that time, clinical experience with ARVC/D was dominated by symptomatic index cases and sudden cardiac death victims-the overt or severe end of the disease spectrum. Consequently, the 1994 criteria were highly specific but lacked sensitivity for early and familial disease.

METHODS AND RESULTS

Revision of the diagnostic criteria provides guidance on the role of emerging diagnostic modalities and advances in the genetics of ARVC/D. The criteria have been modified to incorporate new knowledge and technology to improve diagnostic sensitivity, but with the important requisite of maintaining diagnostic specificity. The approach of classifying structural, histological, electrocardiographic, arrhythmic, and genetic features of the disease as major and minor criteria has been maintained. In this modification of the Task Force criteria, quantitative criteria are proposed and abnormalities are defined on the basis of comparison with normal subject data.

CONCLUSIONS

The present modifications of the Task Force Criteria represent a working framework to improve the diagnosis and management of this condition. Clinical Trial Registration clinicaltrials.gov Identifier: NCT00024505.

Activation of the endogenous coagulation system in patients with atrial flutter: relationship to echocardiographic markers of thromboembolic risk

BACKGROUND

Atrial thrombus formation in patients with atrial flutter raises concerns of stroke risk. We investigated patients with isthmus-dependent atrial flutter for coagulation abnormalities before and after cardioversion to sinus rhythm by catheter ablation, and evaluated the relationship of the abnormalities to the echocardiographic risk markers of stroke.

METHODS AND RESULTS

Plasma samples were drawn prior to insertion of catheters, immediately after the procedure, and 24 hours afterwards. At baseline, coagulation abnormalities were found in 22 out of 25 patients (88%). von Willebrand factor antigen (vWF-Ag) and factor VIII:C were elevated in 17 patients (68%) and 15 patients (60%), respectively. At baseline, mean plasma levels of vWF-Ag (250.1 +/- 144.4%) and factor VIII:C (215.0 +/- 77.1%) were increased. Key markers of thrombin generation, thrombin-antithrombin III complex (TAT; 47.8 +/- 30.9 microg/L vs 14.5 +/- 13.8 microg/L; p < 0.05) and prothrombin fragments 1.2 (F1.2; 2.5 +/- 0.5 nmoL/L vs 1.2 +/- 1.0 nmoL/L) were significantly elevated in the presence of spontaneous echo contrast. Further, both markers of thrombin generation inversely correlated with left atrial appendage emptying velocity (r = -0.42 and -0.63, p < 0.05). Levels of TAT and F1.2 increased after conversion and ablation.

CONCLUSIONS

Endothelial-dependent coagulation factors were enhanced in most patients with atrial flutter. Spontaneous echo contrast and decreased atrial contractility were associated with increased thrombin generation. After conversion and ablation, an increase in thrombin generation and fibrinolysis suggest a transient pro-thrombotic state.

Cardioprotection with beta-blockers: myths, facts and Pascal's wager

Beta-blockers were documented to reduce reinfarction rate more than 3 decades ago and subsequently touted as being cardioprotective for a broad spectrum of cardiovascular indications such as hypertension, diabetes, angina, atrial fibrillation as well as perioperatively in patients undergoing surgery. However, despite lowering blood pressure, beta-blockers have never shown to reduce morbidity and mortality in uncomplicated hypertension. Also, beta-blockers do not prevent heart failure in hypertension any better than any other antihypertensive drug class. Beta-blockers have been shown to increase the risk on new onset diabetes. When compared with nondiuretic antihypertensive drugs, beta-blockers increase all-cause mortality by 8% and stroke by 30% in patients with new onset diabetes. Beta-blockers are useful for rate control in patients with chronic atrial fibrillation but do not help restore sinus rhythm or have antifibrillatory effects in the atria. Beta-blockers provide symptomatic relief in patients with chronic stable angina but do not reduce the risk of myocardial infarction. Adverse effects of beta-blockers are common including fatigue, dizziness, depression and sexual dysfunction. However, beta-blockers remain a cornerstone in the management of patients having suffered a myocardial infarction and for patients with heart failure. Thus, recent evidence argues against universal cardioprotective properties of beta-blockers but attest to their usefulness for specific cardiovascular indications.

Prevalence, predictors, and prognosis of atrial fibrillation early after pulmonary vein isolation: findings from 3 months of continuous automatic ECG loop recordings

INTRODUCTION

Following pulmonary vein isolation (PVI) for atrial fibrillation (AF), early recurrences are frequent, benign and classified as a part of a "blanking period." This study characterizes early recurrences and determines implications of early AF following PVI.

METHODS AND RESULTS

Seventy-two consecutive patients (59.8 +/- 10.7 years, 69% male) were studied following PVI for paroxysmal or persistent AF. Subjects were fitted with an external loop recorder for automatic, continuous detection of AF recurrence for 3 months. AF prevalence was highest 2 weeks after PVI (54%) and declined to an eventual low of 22%. A significant number (488, 34%) of recurrences were asymptomatic; however, all patients with > or =1 AF event had > or =1 symptomatic event. No clear predictor of early recurrence was identified. Forty-seven (65%) patients had at least 1 AF episode, predominantly (39 of 47 patients, 83%) within 2 weeks of PVI. Of the 33 patients who did not experience AF within the first 2 weeks, 85% (28/33) were complete responders (P = 0.03) at 12 months. Recurrence at any time within 3 months was not associated with procedural success or failure.

CONCLUSIONS

Early AF recurrence peaks within the first few weeks after PVI, but continues at a lower level until the completion of monitoring. A blanking period of 3 months is justified to identify patients with AF recurrences that do not portend procedure failure. Freedom from AF in the first 2 weeks following ablation significantly predicts long-term AF freedom.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia clinical presentation and diagnostic evaluation: results from the North American Multidisciplinary Study

BACKGROUND

Prior reports on patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) focused on individuals with advanced forms of the disease. Data on the diagnostic performance of various testing modalities in newly identified individuals suspected of having ARVC/D are limited.

OBJECTIVE

The purpose of the Multidisciplinary Study of Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia was to study the clinical characteristics and diagnostic evaluation of a large group of patients newly identified with ARVC/D.

METHODS

A total of 108 newly diagnosed patients with suspected ARVC/D were prospectively enrolled in the United States and Canada. The patients underwent noninvasive and invasive tests using standardized protocols that initially were interpreted by the enrolling center and adjudicated by blind analysis in six core laboratories. Patients were followed for a mean of 27 +/- 16 months (range 0.2-63 months).

RESULTS

The clinical profile of these newly diagnosed patients differs from the profile of reported patients with more advanced disease. There was considerable difference in the initial and final classification of the presence of ARVC/D after the diagnostic tests were evaluated by the core laboratories. Final clinical diagnosis was 73 affected, 28 borderline, and 7 unaffected. Individual tests agreed with the final diagnosis in 50% to 70% of the 73 patients with a final classification of affected.

CONCLUSION

The clinical profile of 108 newly diagnosed probands with suspected ARVC/D indicates that a combination of diagnostic tests is needed to evaluate the presence of right ventricular structural, functional, and electrical abnormalities. Echocardiography, right ventricular angiography, signal-averaged ECG, and Holter monitoring provide optimal clinical evaluation of patients suspected of ARVC/D.

Influence of left ventricular lead location on outcomes in the COMPANION study

INTRODUCTION

There are no randomized controlled trial data that evaluate mortality and hospitalization rates in cardiac resynchronization therapy (CRT) recipients based on left ventricular (LV) lead location. We analyzed the event-driven outcomes of mortality and hospitalization as well as functional outcomes including Functional Class, Quality-of-Life, and 6-minute walk distance in 1,520 patients enrolled in the COMPANION study of CRT versus optimal medical therapy.

METHODS AND RESULTS

Over a mean follow-up after implantation of 16.2 months, patients randomized to CRT, regardless of lead location, experienced benefit compared with optimized pharmacologic therapy (OPT), with respect to all-cause mortality or heart failure hospitalization. All but a posterior location showed benefit with respect to the all-cause mortality or all-cause hospitalization outcome. Mortality benefit in CRT-D patients was indifferent to LV lead position. All functional outcomes including 6-minute walk distance, Quality-of-Life (QOL) and Functional Class improved with CRT, regardless of LV lead location.

CONCLUSION

LV lead location was not a major determinant of multiple measures of response to CRT therapy in the COMPANION Trial. While acute data indicate that a left lateral LV lead location results in the most favorable hemodynamic response, these chronic data suggest that positioning an LV lead in an anterior rather than a lateral or posterior LV location has similar benefit.

Cardiac Resynchronization Therapy Reduces the Risk of Hospitalizations in Patients With Advanced Heart Failure

Background— In the Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure (COMPANION) trial, 1520 patients with advanced heart failure were assigned in a 1:2:2 ratio to optimal pharmacological therapy or optimal pharmacological therapy plus cardiac resynchronization therapy (CRT-P) or CRT with defibrillator (CRT-D). Use of CRT-P and CRT-D was associated with a significant reduction in combined risk of death or all-cause hospitalizations. Because mortality also was significantly reduced (optimal pharmacological therapy versus CRT-D only), an assessment of the true reduction in hospitalization rates must consider the competing risk of death and varying follow-up times.

Methods and Results— To overcome the challenges of comparing treatment groups, we used a nonparametric test of right-censored recurrent events that accounts for multiple hospital admissions, differential follow-up time between treatment groups, and death as a competing risk. An end-point committee adjudicated and classified all hospitalizations. Compared with optimal pharmacological therapy, CRT-P and CRT-D were associated with a 21% and 25% reduction in all-cause, 34% and 37% reduction in cardiac, and 44% and 41% reduction in heart failure hospital admissions per patient-year of follow-up, respectively. Similar reductions were seen in hospitalization days per patient-year. The reduction in hospitalization rate for heart failure in the CRT groups appeared within days of randomization and remained sustained. Noncardiac hospitalization rates were not different between groups.

Conclusion— Use of CRT with or without a defibrillator in advanced heart failure patients was associated with marked reductions in all-cause, cardiac, and heart failure hospitalization rates in an analysis that accounted for the competing risk of mortality and unequal follow-up time.

Atrial fibrillation independently prolongs hospital stay after coronary artery bypass surgery

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia occurring in patients after coronary artery bypass surgery (CABG).

HYPOTHESIS

The purpose of this study was to determine whether AF independently prolonged postoperative length of stay (LOS).

METHODS

Consecutive patients undergoing elective CABG were identified. Baseline clinical variables, postoperative course including the development of AF, and postoperative LOS were recorded.

RESULTS

In all, 216 patients (aged 61 +/- 13 years) were examined. Postoperative LOS was 11.3 +/- 6.4 days (median LOS = 9 days). Fifty-five patients (25%) developed AF. Among 16 variables examined, the univariate predictors of LOS included age (p < 0.001), preoperative left ventricular ejection fraction (p < 0.001), absence of a prior smoking history (p < 0.05), bypass limited to venous conduits (p < 0.001), postoperative AF (p < 0.001), and the occurrence of a postoperative event (p < 0.001). Length of stay for patients who developed AF was significantly longer than that for patients who did not (15.1 +/- 9.0 vs. 10.0 +/- 4.6 days, p < 0.001). After adjusting for other significant variables, the occurrence of AF after CABG independently prolonged LOS: patients who developed AF stayed 3.2 +/- 1.7 days longer than patients who did not (p < 0.001).

CONCLUSIONS

Atrial fibrillation lengthens hospital stay after CABG, and its effect is independent of other important variables. Identification of patients who are at risk for AF and successful treatment to prevent AF will likely contribute to major reductions in consumption of health care resources in patients with CABG.

Implantable cardioverter defibrillator discharge rates in patients with unexplained syncope, structural heart disease, and inducible ventricular tachycardia at electrophysiologic study

BACKGROUND AND HYPOTHESIS

The implantable cardioverter defibrillator (ICD) is the best available strategy to protect patients from life-threatening ventricular arrhythmia. Although unproven, it is commonly utilized to treat subjects with syncope, a negative clinical workup, structural heart disease, and inducible sustained monomorphic ventricular tachycardia (VT) on programmed electrophysiologic stimulation (EPS). The purpose of this paper was to validate this approach.

METHODS

We retrospectively identified 36 subjects who received primary ICD therapy for syncope in the setting of structural heart disease with inducible sustained monomorphic VT on EPS. The cohort was predominantly male (32/36) with underlying coronary artery disease (29/36). The mean left ventricular ejection fraction was 31 +/- 12%, and a third of the patients (12/36) had undergone bypass surgery.

RESULTS

The study group was followed for a mean of 23 +/- 15 months (range 3-81 months) and experienced an ICD event rate of 22% at 3 months, which increased to 55% at 36 months. This event rate was comparable with the 66% event rate seen in a group of patients with primary ICD therapy for spontaneous life-threatening VT treated during the same time period. No future predictors of ICD events in the study group could be identified.

CONCLUSION

Syncope patients with negative workup, structural heart disease, and sustained monomorphic VT at EPS are at high risk for future tachyarrhythmic events. Based on present evidence, primary ICD therapy in this group appears warranted and justified.

Cardiac resynchronization therapy and atrial fibrillation

Cardiac resynchronization therapy (CRT) is an important advance for the treatment of end-stage heart failure (HF). About 15-50% of HF is complicated by atrial fibrillation (AF), associated with worsened outcomes. The presence of AF may interfere with optimal delivery of CRT due to competition with biventricular (BiV) capture by conducted beats. Pacing algorithms in newer devices may not ensure consistent CRT delivery during periods of rapid ventricular rates. Atrioventricular junction ablation with permanent pacing eliminates interference by conducted beats and provides complete BiV capture and is associated with improved outcomes. Catheter ablation of AF is another promising alternative to maintain sinus rhythm in patients with AF and HF. However, the optimal indications for CRT delivery for patients in this complex cohort remain to be assessed in randomized clinical trials.

Dexmedetomidine sedation leading to refractory cardiogenic shock

Dexmedetomidine is frequently used for deep sedation during electrophysiology procedures. We report a case where, presumably, the use of dexmedetomidine resulted in a patient's death. The patient developed unexplained and refractory cardiogenic shock and could not be resuscitated. Autopsy failed to demonstrate any abnormality or cause of death. We postulate that, in certain susceptible individuals, dexmedetomidine may lead to terminal complications. We therefore urge caution about using dexmedetomidine in the electrophysiology laboratory.

Inappropriate implantable cardioverter-defibrillator shocks in MADIT II: frequency, mechanisms, predictors, and survival impact

OBJECTIVES

This study sought to identify the incidence and outcome related to inappropriate implantable cardioverter-defibrillator (ICD) shocks, that is, those for nonventricular arrhythmias.

BACKGROUND

The MADIT (Multicenter Automatic Defibrillator Implantation Trial) II showed that prophylactic ICD implantation improves survival in post-myocardial infarction patients with reduced ejection fraction. Inappropriate ICD shocks are common adverse consequences that may impair quality of life.

METHODS

Stored ICD electrograms from all shock episodes were adjudicated centrally. An inappropriate shock episode was defined as an episode during which 1 or more inappropriate shocks occurred; another inappropriate ICD episode occurring within 5 min was not counted. Programmed parameters for patients with and without inappropriate shocks were compared.

RESULTS

One or more inappropriate shocks occurred in 83 (11.5%) of the 719 MADIT II ICD patients. Inappropriate shock episodes constituted 184 of the 590 total shock episodes (31.2%). Smoking, prior atrial fibrillation, diastolic hypertension, and antecedent appropriate shock predicted inappropriate shock occurrence. Atrial fibrillation was the most common trigger for inappropriate shock (44%), followed by supraventricular tachycardia (36%), and then abnormal sensing (20%). The stability detection algorithm was programmed less frequently in patients receiving inappropriate shocks (17% vs. 36%, p = 0.030), whereas other programming parameters did not differ significantly from those without inappropriate shocks. Importantly, patients with inappropriate shocks had a greater likelihood of all-cause mortality in follow-up (hazard ratio 2.29, p = 0.025).

CONCLUSIONS

Inappropriate ICD shocks occurred commonly in the MADIT II study, and were associated with increased risk of all-cause mortality.

Atrial fibrillation and obesity--results of a meta-analysis

BACKGROUND

Obesity has been shown to be associated with atrial enlargement and ventricular diastolic dysfunction, both of which are risk factors for atrial fibrillation (AF). However, the role of obesity as a risk factor for the development of AF is unknown. The study aims to evaluate the role of obesity as a risk factor for the development of AF.

METHODS

The MEDLINE/ PUBMED and Cochrane databases were searched for studies in human subjects published in English language between 1966 and May 2007. Studies were included in our analyses if they were population-based cohort or postcardiac surgery cohort and investigated the incidence of AF in relation to the body mass index (BMI) categories.

RESULTS

Of the 468 articles identified, 16 studies that enrolled a total of 123,249 individuals met the inclusion criteria. These 16 articles included 5 population-based cohort studies that enrolled 78,602 adult individuals from the United States and 3 European countries and 11 postcardiac surgery studies that enrolled 44,647 patients. Based on the population-based cohort studies, obese individuals have an associated 49% increased risk of developing AF compared to nonobese individuals (relative risk 1.49, 95% CI 1.36-1.64). The risk of AF increased in parallel with greater BMI in this cohort. In contrast, in the postcardiac surgery studies, obese individuals do not have an associated increased risk of developing AF compared to nonobese individuals (relative risk 1.02, 95% CI 0.99-1.06).

CONCLUSIONS

Our findings demonstrate that obesity increased the risk of developing AF by 49% in the general population, and the risk escalated in parallel with increased BMI. Thus, AF evolves as yet another pathogenetic factor by which obesity may increase cardiovascular and cerebrovascular events.

Antiarrhythmic induced electrical storm in Brugada syndrome: a case report

Brugada syndrome (BS) may be "unmasked" by several pharmacological and/or physiological agents in an otherwise normal electrocardiogram. Once diagnosed the possibility of persistent ventricular tachycardia/fibrillation exists. Although this is treated with various antiarrhythmic agents, there remains a cohort of patients who fail to respond to conventional antiarrhythmic therapy therefore, amplifying the electrical storm. We report a case of a BS diagnosed via procainamide challenge, the resultant near fatal electrical storm aggravated by amiodarone and the eventual resolution with isoproterenol.

Upstream Treatments for Atrial Fibrillation

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Role of Electrophysiologic Studies, Signal‐Averaged Electrocardiography, Heart Rate Variability, T‐Wave Alternans, and Loop Recorders for Risk Stratification of Ventricular Arrhythmias

Ventricular tachycardia and fibrillation are major causes of morbidity and mortality after myocardial infarction. Frequently, sudden cardiac death is the first manifestation of such malignant rhythms. Optimal risk stratification strategies in this population are of utmost importance. In this review the authors discuss the background and clinical use of invasive tests, such as electrophysiologic study and implantable loop recorders, and noninvasive tests, such as signal-averaged electrocardiography, heart rate variability, and T-wave alternans. The utility, indications, and limitations of each test in clinical practice are discussed, especially for the purpose of postmyocardial infarction risk stratification in the elderly population.