Worldwide epidemiology of atrial fibrillation: a Global Burden of Disease 2010 Study.

BACKGROUND: The global burden of atrial fibrillation (AF) is unknown. METHODS AND RESULTS: We systematically reviewed population-based studies of AF published from 1980 to 2010 from the 21 Global Burden of Disease regions to estimate global/regional prevalence, incidence, and morbidity and mortality related to AF (DisModMR software). Of 377 potential studies identified, 184 met prespecified eligibility criteria. The estimated number of individuals with AF globally in 2010 was 33.5 million (20.9 million men [95% uncertainty interval (UI), 19.5-22.2 million] and 12.6 million women [95% UI, 12.0-13.7 million]). Burden associated with AF, measured as disability-adjusted life-years, increased by 18.8% (95% UI, 15.8-19.3) in men and 18.9% (95% UI, 15.8-23.5) in women from 1990 to 2010. In 1990, the estimated age-adjusted prevalence rates of AF (per 100 000 population) were 569.5 in men (95% UI, 532.8-612.7) and 359.9 in women (95% UI, 334.7-392.6); the estimated age-adjusted incidence rates were 60.7 per 100 000 person-years in men (95% UI, 49.2-78.5) and 43.8 in women (95% UI, 35.9-55.0). In 2010, the prevalence rates increased to 596.2 (95% UI, 558.4-636.7) in men and 373.1 (95% UI, 347.9-402.2) in women; the incidence rates increased to 77.5 (95% UI, 65.2-95.4) in men and 59.5 (95% UI, 49.9-74.9) in women. Mortality associated with AF was higher in women and increased by 2-fold (95% UI, 2.0-2.2) and 1.9-fold (95% UI, 1.8-2.0) in men and women, respectively, from 1990 to 2010. There was evidence of significant regional heterogeneity in AF estimations and availability of population-based data. CONCLUSIONS: These findings provide evidence of progressive increases in overall burden, incidence, prevalence, and AF-associated mortality between 1990 and 2010, with significant public health implications. Systematic, regional surveillance of AF is required to better direct prevention and treatment strategies.

Comparing classifications of death in the Mode Selection Trial: agreement and disagreement among site investigators and a clinical events committee.

Clinical events committees (CECs) are the current standard for endpoint adjudication in clinical trials. However, little data exist with which to compare CEC and site investigator determinations or to evaluate internal agreement among CEC members. Using data from the Mode Selection Trial in Sinus Node Dysfunction (MOST), we analyzed classifications of death in order to compare internal agreement among CEC physician reviewers and agreement between the CEC and site investigators. Death was classified at 2 levels: by major cause (cardiac, noncardiac, or unknown) and by minor subclassification of the major classifications. Reviewer agreement was tabulated at the major and minor levels, and standard and weighted kappa statistics were calculated. Disagreement at both levels was also determined. Individual decision-making was tabulated in terms of frequency in classifying death as unknown. All 404 deaths were classified by the CEC. Site investigators determined major classifications in 382 cases and minor classification in 379 cases. The CEC and the site investigators disagreed in classifying 41 cases (10.7%) at the major level and 117 (30.9%) at the minor level. CEC reviewers disagreed internally at the major level in 64 cases (15.8%), at the minor level in 63 cases (15.6%), and at any level in 127 cases (31.4%) (kappa = 0.60, 95% confidence interval (CI) [0.55, 0.66]; weighted kappa = 0.66, 95% CI [0.62, 0.75]). In resolving internal disagreements, the full CEC agreed with 1 of 2 CEC reviewers in 85.9% of cases. Disagreements occurred between site investigators and CEC reviewers in classifying deaths. Endpoint determination and decision-making varied among individual CEC reviewers, but second-tier reviews by the full CEC resolved all disagreements. These findings support continued use of CECs for endpoint adjudication in clinical trials.

Electrophysiologic predictors of the recurrence of persistent atrial fibrillation within 30 days of cardioversion.

Patients with recurrence of persistent atrial fibrillation within 30 days of cardioversion had slower atrial conduction, a slower sinus rate, no difference in the absolute value of the effective refractory period, greater early reverse remodeling of the effective refractory period, and more premature atrial contractions than those who did not. These findings highlight the role of slow conduction and premature atrial contractions in the pathophysiology of atrial fibrillation and suggest a possible proarrhythmic effect of reverse remodeling.

Arrhythmias in pregnancy.

Pregnant women have an increased risk of having the usual arrhythmias seen in women of childbearing age. Most of these are benign sinus tachycardias or bradycardias or atrial and ventricular ectopic beats. Women who have had sustained supraventricular or ventricular tachycardias before pregnancy frequently develop them during pregnancy. These arrhythmias often have enough hemodynamic significance to decrease uterine blood flow, which adds a sense of urgency for treatment. The management is similar to that of nonpregnant women, with nuances important for the protection of the developing fetus.

Treatment of inadvertent pericardial placement of a tunneled dialysis catheter by direct thrombin injection.

An inadvertent case of pericardial placement of a central venous catheter was successfully treated by direct thrombin injection.

Native QRS duration predicts the occurrence of arrhythmic events in ICD recipients.

AIMS: Identification of implantable cardioverter/defibrillator (ICD) recipients at higher risk of future therapies may assist in pre-empting future shocks. Native QRS duration is an established predictor of overall mortality, but the role of this parameter as a clinical predictor of arrhythmic events warrants further investigation. METHODS AND RESULTS: In an analysis of a single-centre, 13-year ICD implantation experience (1990-2002), multiple clinical parameters including QRS duration were analysed using a multiple logistic regression model. Of 562 patients followed for at least 1 year, 98 (17%) did not receive ICD therapies (event-free, group A). Comparisons were made with a randomly selected sample of 123 patients who received ICD therapies (arrhythmic events, group B). There were no significant differences in age, gender, frequency of coronary artery disease, and degree of left ventricular dysfunction. However, QRS duration was a significant determinant of arrhythmic events (> or =100 vs. <100 ms: adjusted OR 2.75, 95% CI 1.37-5.51; > or =120 vs. <120 ms: adjusted OR 1.77, 95% CI 0.97-3.23). QRS duration was also a predictor of overall mortality in the logistic regression models (> or =100 ms: adjusted OR 3.72, 95% CI 1.17-11.9; > or =120 ms: adjusted OR 3.09, 95% CI 1.39-6.85). CONCLUSION: In this ICD population, consisting largely of secondary prevention ICD recipients, longer QRS duration predicted higher likelihood of arrhythmic events. Extent of QRS prolongation could guide the decision to initiate prophylactic anti-arrhythmic therapy in ICD patients.

Population-based analysis of sudden cardiac death with and without left ventricular systolic dysfunction: two-year findings from the Oregon Sudden Unexpected Death Study.

OBJECTIVES: We sought to evaluate the contribution of left ventricular (LV) dysfunction toward occurrence of sudden cardiac death (SCD) in the general population, and to identify distinguishing characteristics of SCD in the absence of LV dysfunction. BACKGROUND: Patients who manifest warning symptoms and signs are more likely to undergo evaluation before SCD. Although prevalence of LV dysfunction in this subgroup may overestimate the prevalence in overall SCD, this is the only means of assessment in the general population. METHODS: All cases of SCD in Multnomah County, Oregon (population 660,486; 2002 to 2004) were prospectively ascertained in the ongoing Oregon Sudden Unexpected Death Study. We retrospectively assessed LV ejection fraction (LVEF) among subjects who underwent evaluation of LV function before SCD (normal: > or =55%; mildly to moderately reduced: 36% to 54%; and severely reduced: < or =35%). Of a total of 714 SCD cases (annual incidence 54 per 100,000), LV function was assessed in 121 (17%). RESULTS: The LVEF was severely reduced in 36 patients (30%), mildly to moderately reduced in 27 (22%), and normal in 58 (48%). Patients with normal LVEF were distinguishable by younger age (66 +/- 15 years vs. 74 +/- 10 years; p = 0.001), higher proportion of females (47% vs. 27%; p = 0.025), higher prevalence of seizure disorder (14% vs. 0%; p = 0.002), and lower prevalence of established coronary artery disease (50% vs. 81%; p < 0.001). CONCLUSIONS: In this community-wide study, only one-third of the evaluated SCD cases had severe LV dysfunction meeting current criteria for prophylactic cardioverter-defibrillator implantation. The SCD cases with normal LV function had several distinguishing clinical characteristics. These findings support the aggressive development of alternative screening methods to enhance identification of patients at risk.

Arrhythmias after orthotopic heart transplantation.

BACKGROUND: Arrhythmias frequently occur after orthotopic heart transplantation (OHT). METHODS AND RESULTS: The most common are ventricular premature complexes, atrial premature complexes, sinus or junctional bradycardia, atrial fibrillation, and atrial flutter, all of which have varying clinical significance depending on associated or causative conditions. Unique etiologic factors such as allograft rejection, transplant coronary artery disease, and altered anatomy and autonomic nervous system changes require that arrhythmias be treated differently after OHT compared with the general population. CONCLUSION: The potentially severe ramifications of allograft rejection and coronary artery disease make treatment of these disorders in the setting of arrhythmias as important as treating the arrhythmias themselves. At the same time, autonomic denervation and altered anatomy after transplantation complicate drug and device therapies.

Arrhythmia Therapy in the Elderly.

As with other illnesses, the risks and benefits of diagnostic studies and treatments for arrhythmias are altered by age. In the elderly, the risks of treatment are often greater; drug metabolism varies and mechanical approaches (ablation procedures and insertion of electrical devices) are associated with greater complication rates. This paper reviews recommendations for diagnosis and treatment of arrhythmias in the elderly. (c) 2000 by CVRR, Inc.

Reversal of electrical remodeling after cardioversion of persistent atrial fibrillation.

INTRODUCTION: In animals, atrial fibrillation results in reversible atrial electrical remodeling manifested as shortening of the atrial effective refractory period, slowing of intra-atrial conduction, and prolongation of sinus node recovery time. There is limited information on changes in these parameters after cardioversion in patients with persistent atrial fibrillation. METHODS AND RESULTS: Thirty-eight patients who had been in atrial fibrillation for 1 to 12 months underwent electrophysiologic testing 10 minutes and 1 hour after cardioversion. At 1 week, 19 patients still in sinus rhythm returned for repeat testing. Reverse remodeling of the effective refractory period was not uniform across the three atrial sites tested. At the lateral right atrium, there was a highly significant increase in the effective refractory period between 10 minutes and 1 hour after cardioversion (drive cycle length 400 ms: 204 +/- 17 ms vs 211 +/- 20 ms, drive cycle length 550 ms: 213 +/- 18 ms vs 219 +/- 23 ms, P < 0.001). The effective refractory period at the coronary sinus and distal coronary sinus did not change in the first hour but had increased by 1 week. The corrected sinus node recovery time did not change in the first hour but was shorter at 1 week (606 +/- 311 ms vs 408 +/- 160 ms, P = 0.009). P wave duration also was shorter at 1 week (135 +/- 18 ms vs 129 +/- 13 ms, P = 0.04) consistent with increasing atrial conduction velocity. CONCLUSION: The atrial effective refractory period increases, sinus node function improves, and atrial conduction velocity goes up in the first week after cardioversion of long-standing atrial fibrillation in humans. Reverse electrical remodeling of the effective refractory period occurs at different rates in different regions of the atrium.

Nonautomatic focal atrial tachycardia: characterization and ablation of a poorly understood arrhythmia in 38 patients.

Nonautomatic focal atrial tachycardia (NAFAT) is a rare and poorly understood arrhythmia either due to microreentry or triggered mechanism. NAFAT was defined as a focal atrial tachycardia which was inducible with pacing maneuvers in the electrophysiology lab. We reviewed the charts and EP study reports of all 38 patients with NAFAT, who underwent an EP study at our center between April 1994 and September 2000. Patients' were predominantly female (n = 31, 82%), aged 11-78 years (median 46). The mean age at presentation was 31 years (range 7-71 years). None of the patients had structural heart disease or had undergone prior heart surgery. Electroanatomic mapping (EAM) was performed in 22 patients and showed no scars in the atrium. A total of 45 foci were identified (range 1-3 foci/patient). Anatomically NAFAT foci were predominantly right atrial (n = 35) rather than left (n = 10). The NAFAT cycle length ranged from 270 to 490 (mean +/- SD; 380 +/- 69 ms) and was significantly lower in patients younger than 24 years of age. Ablation, attempted for 42 foci was successful in 33 (79%). The success rate in the EAM group was 20/25 foci (80%) compared to 13/18 (72%) in the non-EAM group. In conclusion, NAFAT is a rare arrhythmia which predominantly affects women with no other associated cardiac disease. It mainly occurs in the right atrium, affects all ages and is amenable to catheter ablation.