Catheter Ablation of Recurrent Lone Atrial Fibrillation in Teenagers with a Structurally Normal Heart.

BACKGROUND: Atrial fibrillation (AF) is rare in teenagers. There are few reports and no clear guidelines on the management of AF with catheter ablation in teenagers. METHODS: A case series of teenagers (<18 years) with paroxysmal AF and a structurally normal heart who underwent catheter ablation was undertaken. RESULTS: Four teenage boys aged 15-17 years underwent catheter ablation of AF. All but one had failed antiarrhythmic medical therapy. Two had focal triggers and underwent culprit vein isolation (one recurred and so underwent isolation of an additional vein), and two had no focal triggers identified and so underwent isolation of all four pulmonary veins (PVs). At follow-up ranging from 2-6 years, one patient who underwent isolation of all four veins had recurrence of paroxysmal AF. All others have had medium and long-term success with complete absence of AF. None are on long-term antiarrhythmic therapy. No patient had a procedural or postprocedure complication. CONCLUSIONS: A cautious attempt at catheter ablation may be appropriate in teenagers with paroxysmal AF and a structurally normal heart who fail pharmacologic therapy. Culprit vein(s) isolation should be preferred if possible but if no focal triggers are identified, isolation of all PVs appears to be beneficial.

Pacemaker and implantable cardioverter-defibrillator use in a US myotonic dystrophy type 1 population.

INTRODUCTION: We assessed implant rates, indications, characteristics, and outcomes in patients with the neuromuscular disease, myotonic dystrophy type 1 (DM1) receiving a pacemaker or an implantable cardioverter-defibrillator (ICD). METHODS AND RESULTS: Device use was evaluated in a prospective, multicenter registry of 406 genetically confirmed adult patients followed for 9.5 ± 3.2 years. Forty-six (11.3%) had or received a pacemaker and 21 (5.2%) received an ICD. Devices were primarily implanted for asymptomatic conduction abnormalities and left ventricular (LV) systolic dysfunction. However, 7 (15.2%) pacemakers were implanted for third-degree atrioventricular block and 6 (28.6%) ICDs were implanted for ventricular tachyarrhythmias (ventricular tachycardia [VT] or fibrillation [VF]). Patients receiving devices were older and more frequently had heart failure, LV systolic dysfunction, atrial tachyarrhythmias, and ECG conduction abnormalities compared to nondevice patients. Five (10.9%) pacemaker patients underwent upgrade to an ICD, 3 for LV systolic dysfunction, 1 for VT/VF, and 1 for progressive conduction disease. Seventeen (27.4%) of the 62 patients with devices were pacemaker-dependent at last follow-up. Three (14.3%) ICD patients had appropriate therapies. Twenty-four (52.2%) pacemaker patients died including 13 of respiratory failure and 7 of sudden death. Seven (33.3%) ICD patients died including 2 of respiratory failure and 3 of sudden death. The patients with ICDs and sudden death all had LV systolic dysfunction and 1 death was documented due to inappropriate therapies. CONCLUSIONS: DM1 patients commonly receive antiarrhythmia devices. The risk of VT/VF and sudden death suggests that ICDs rather than pacemakers should be considered for these patients.

Simplified demonstration of cavotricuspid isthmus block after catheter ablation in patients after Mustard's operation.

BACKGROUND: The Mustard operation is a complex atrial rerouting performed in patients with transposition of the great arteries (TGA). Cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) is an important problem in these patients. While catheter ablation (CA) is successful, three-dimensional (3D) mapping is necessary to prove block at the CTI. 3D mapping, however, requires baffle puncture. We tested a simplified concept to prove isthmus block after CA for AFL in Mustard patients. METHODS: During electrophysiology study, catheters were placed in the high and low systemic venous atrium (HSVA and LSVA) and in the low pulmonary venous atrium (LPVA). LPVA and then LSVA were paced while recording in the HSVA and the alternate site. While pacing from one low site, the time taken to activate the other low site and the HSVA was compared before and after successful ablation. RESULTS: Three patients with Mustard operation and AFL underwent successful CA. Involvement of the CTI in AFL was proved by entrainment mapping. AFL was terminated during ablation and no longer inducible after ablation in all. LSVA pacing showed LPVA activation preceded HSVA activation preablation and activation pattern reversal after ablation. Likewise, LPVA pacing showed LSVA activation preceding HSVA preablation with reversal after ablation. CONCLUSION: This study provides a simple method to demonstrate bidirectional block at the CTI in patients with CTI-based AFL after Mustard operation for TGA.

Safety of electronic apex locators and pulp testers in patients with implanted cardiac pacemakers or cardioverter/defibrillators.

The purpose of this study was to determine if electronic apex locators (EAL) or electric pulp testers (EPT) interfere with the function of implanted cardiac pacemakers (ICP) or cardioverter/defibrillators (ICD). Twenty-seven patients with ICPs or ICDs had continuous electrocardiogram monitoring and device interrogation to detect interferences during the use of two types of EALs and one EPT. No interferences were detected by any ICP or ICD. In six patients, with intermittent pacing, a significant increase in pacing was observed during EAL/EPT stimulation (p < 0.05). Examination of RR intervals (a measure of intrinsic heart rate) demonstrated significantly longer RR intervals (slower intrinsic heart rate) during EAL/EPT stimulation (p < 0.05). Evaluation of the electrocardiograms for each patient failed to show any abnormalities in pacing during testing. These findings led us to conclude that the increased pacing frequency observed was related to a slower intrinsic heart rate and not electrical interference with the cardiac devices. In conclusion, the two EALs and one EPT used in this study did not interfere with the functioning of any of the cardiac devices tested.

Analysis of cause-specific mortality in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study.

BACKGROUND: Expectations that reestablishing and maintaining sinus rhythm in patients with atrial fibrillation might improve survival were disproved in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study. This report describes the cause-specific modes of death in the AFFIRM treatment groups. METHODS AND RESULTS: All deaths in patients enrolled in AFFIRM underwent blinded review by the AFFIRM Events Committee, and a mode of death was assigned. In AFFIRM, 2033 patients were randomized to a rhythm-control strategy and 2027 patients to a rate-control strategy. During a mean follow-up of 3.5 years, there were 356 deaths in the rhythm-control patients and 310 deaths in the rate-control patients (P=0.07). In the rhythm-control group, 129 patients (9%) died of a cardiac cause, and in the rate-control group, 130 patients (10%) died (P=0.95). Both groups had similar rates of arrhythmic and nonarrhythmic cardiac deaths. The numbers of vascular deaths were similar in the 2 groups: 35 (3%) in the rhythm-control group and 37 (3%) in the rate-control group (P=0.82). There were no differences in the rates of ischemic stroke and central nervous system hemorrhage. In the rhythm-control group, there were 169 noncardiovascular deaths (47.5% of the total number of deaths), whereas in the rate-control arm, there were 113 noncardiovascular deaths (36.5% of the total number of deaths) (P=0.0008). Differences in noncardiovascular death rates were due to pulmonary and cancer-related deaths. CONCLUSIONS: Management of atrial fibrillation with a rhythm-control strategy conferred no advantage over a rate-control strategy in cardiac or vascular mortality and may be associated with an increased noncardiovascular death rate.

Current burden of sudden cardiac death: multiple source surveillance versus retrospective death certificate-based review in a large U.S. community.

OBJECTIVES: We sought to determine the annual incidence of sudden cardiac death (SCD) in the general population using a prospective approach. To assess the validity of retrospective surveillance, a simultaneous comparison was made with a death certificate-based method of determining SCD incidence. BACKGROUND: Accurate surveillance and characterization of SCD in the general population is likely to significantly facilitate current and future community-based preventive and therapeutic interventions. METHODS: We performed a prospective evaluation of SCD among all residents of Multnomah County, Oregon (population 660,486) using multiple sources of surveillance. A comprehensive analysis of circumstances of death, medical records, and available autopsy data was performed. Comparisons were made with a retrospective, death certificate-based determination of SCD incidence using International Classification of Diseases-Version 10 codes and location of death. RESULTS: Between February 1, 2002, and January 31, 2003, 353 residents suffered SCD (incidence 53 of 100,000; median age 69 years, 57% male) accounting for 5.6% of overall mortality. Of these, 75 cases (21%) were identified using sources other than first responders. Resuscitation was attempted in 237 cases (67%) and successful (survival to hospital discharge) in 28 (8%). The retrospective death certificate-based review yielded 1,007 cases (incidence 153 of 100,000; median age 81 years, 51% male), and the positive predictive value of this methodology was 19%. CONCLUSIONS: Sudden cardiac death accounts for 5.6% of annual mortality, and prospective evaluation in the general population appears to be feasible. The use of multiple sources of ascertainment and information significantly enhances phenotyping of SCD cases. Retrospective death certificate-based surveillance results in significant overestimation of SCD incidence.

Asymptomatic atrial fibrillation: demographic features and prognostic information from the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study.

BACKGROUND: Atrial fibrillation (AF) may occur without symptoms. Little is known about demographic features and prognostic information in patients with asymptomatic AF. METHODS: In the AFFIRM study, 4060 patients were randomized to either rhythm or rate control. At baseline, patients were identified as asymptomatic if they answered "no" to a 15-item questionnaire related to cardiac symptoms during AF in the 6 months before study entry. RESULTS: There were 481 (12%) asymptomatic patients at baseline. Compared with symptomatic patients, asymptomatic patients were more often men and had a lower incidence of coronary artery disease and congestive heart failure, but had more cerebrovascular events. Asymptomatic patients had a longer duration of AF, a lower maximum heart rate, and better left ventricular function. They received fewer cardiac medications and fewer therapies to maintain sinus rhythm. At 5 years, there was a trend for better survival in asymptomatic patients (81% vs 77%, P = .058), and they were more likely to be free from disabling stroke or anoxic encephalopathy, major bleeding, and cardiac arrest (79% vs 67%, P = .024). However, mortality and major events were similar after correction for baseline differences. CONCLUSIONS: Patients with asymptomatic AF have less serious heart disease but more cerebrovascular disease. Asymptomatic patients receive different therapies than symptomatic patients. However, the absence of symptoms and the differences in treatment does not confer a more favorable prognosis when differences in baseline clinical parameters are considered. Anticoagulation should be considered in these patients.

Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial.

CONTEXT: Clinical studies of omega-3 polyunsaturated fatty acids (PUFAs) have shown a reduction in sudden cardiac death, suggesting that omega-3 PUFAs may have antiarrhythmic effects. OBJECTIVE: To determine whether omega-3 PUFAs have beneficial antiarrhythmic effects in patients with a history of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). DESIGN AND SETTING: Randomized, double-blind, placebo-controlled trial performed at 6 US medical centers with enrollment from February 1999 until January 2003. PATIENTS: Two hundred patients with an implantable cardioverter defibrillator (ICD) and a recent episode of sustained VT or VF. INTERVENTION: Patients were randomly assigned to receive fish oil, 1.8 g/d, 72% omega-3 PUFAs, or placebo and were followed up for a median of 718 days (range, 20-828 days). MAIN OUTCOME MEASURES: Time to first episode of ICD treatment for VT/VF, changes in red blood cell concentrations of omega-3 PUFAs, frequency of recurrent VT/VF events, and predetermined subgroup analyses. RESULTS: Patients randomized to receive fish oil had an increase in the mean percentage of omega-3 PUFAs in red blood cell membranes from 4.7% to 8.3% (P<.001), with no change observed in patients receiving placebo. At 6, 12, and 24 months, 46% (SE, 5%), 51% (5%), and 65% (5%) of patients randomized to receive fish oil had ICD therapy for VT/VF compared with 36% (5%), 41% (5%), and 59% (5%) for patients randomized to receive placebo (P = .19). In the subset of 133 patients whose qualifying arrhythmia was VT, 61% (SE, 6%), 66% (6%), and 79% (6%) of patients in the fish oil group had VT/VF at 6, 12, and 24 months compared with 37% (6%), 43% (6%), and 65% (6%) of patients in the control group (P = .007). Recurrent VT/VF events were more common in patients randomized to receive fish oil (P<.001). CONCLUSION: Among patients with a recent episode of sustained ventricular arrhythmia and an ICD, fish oil supplementation does not reduce the risk of VT/VF and may be proarrhythmic in some patients.

Oral anticoagulation in elderly adults with atrial fibrillation: integrating new options with old concepts.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and the second most common cardiovascular condition in adults in the United States. It is prevalent in the elderly population and is an important risk factor for stroke. Oral anticoagulation offers significant protection against AF-related thromboembolic events, but several complex issues that contribute to its underuse in elderly adults surround it. To aid clinicians in their approach to these problems, a comprehensive PubMed-based search of the literature published in English from 1990 through July 2012 was conducted using the following terms or combination of terms: atrial fibrillation, elderly, antiplatelet, anticoagulation, stroke, bleeding, hemorrhage, and falls. Additional references were identified in a manual search of bibliographies in retrieved articles. The data were then synthesized to address the most relevant questions regarding anticoagulation in elderly adults, including fall risk, responsiveness to warfarin, physician perception of risks, and other barriers to the prescription of anticoagulants. Recently proposed risk-stratification schemes for stroke and hemorrhage that could refine the selection of antithrombotic therapy for AF are highlighted. Finally, available data on the use of antiplatelet therapy, warfarin, and new oral anticoagulants (direct thrombin inhibitor and factor Xa inhibitors) in AF are summarized.

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.

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.

Clinical significance of device-related complications in clinical trials and implications for future trials: insights from the Antiarrhytmics Versus Implantable Defibrillators (AVID) trial.

BACKGROUND: Implantation of transvenous implantable cardioverter-defibrillators (ICDs) utilizing a non-thoracotomy approach has become routine therapy for survivors of life-threatening tachyarrhythmias. In the Antiarrhythmics versus Implantable Defibrillator (AVID) Trial, we sought to identify and prospectively characterize the frequency of lead and ICD-related complications. Between June 1, 1993, and April 7, 1997, 539 patients received non-thoracotomy ICDs. A total of 62 first complications occurred. The subclavian route of insertion resulted in more complications than the cephalic vein route, 46 of 339 (14%) versus 6 of 135 (4%), p =.005 as did the abdominal versus pectoral generator site; 31 of 238 (13%) versus 17 of 291 (6%), p <.02. Most dislodgements and system infections tended to occur in the 3 months following implantation, whereas lead fractures continued to occur throughout follow-up. Failure to use peri-operative antibiotics was a predictor of system infection (p =.001). These data suggest that cephalic vein access and pectoral generator site may result in fewer complications. Although implantation techniques and generator technology continue to evolve, the continued occurrence of lead fractures and the need for premature system revision supports the practice of close routine ICD system surveillance.

Apparent protective effect of increased left ventricular wall thickness in an ICD population.

BACKGROUND: Expanding indications for the implantable cardioverter defibrillator (ICD) call for further enhancement of patient selection for optimization of use. Because a subgroup of patients who receive ICDs may not receive therapies, we sought to identify clinical predictors of therapy-free survival in ICD patients. METHODS: We performed an analysis of a single-center, 13-year ICD implantation experience (1990-2002). The association between therapy-free survival and several clinical variables was evaluated. RESULTS: From a total of 562 patients included in the database, 98 patients (17%) received no shock therapies or antitachycardia pacing (group A). When compared with a randomly selected sample of 131 patients who did receive ICD therapies (group B), there were no significant differences in age, gender, frequency of coronary artery disease, or extent of left ventricular (LV) dysfunction. However, left ventricular hypertrophy (LVH; increased wall thickness by echocardiography) was significantly more common in group A versus group B (30% versus 18%; Pearson's chi-square=4.69, P=.03). The odds of patients in group A having LVH were 1.98 times higher versus group B (95% confidence interval for odds ratio: 1.06-3.71). Comparisons of calculated mean LV mass between the 2 groups were not significantly different (group A 283+/-112 gm versus group B 271+/-108, P=.58). The overall mortality rate was 17% in group A and 22% in group B (P=.29). CONCLUSIONS: Increased LV wall thickness was a significant, independent predictor of therapy-free survival in this ICD population. Because LV mass was unchanged, this finding may reflect the importance of LV dilation and wall thinning (ie, eccentric remodeling) as a risk factor for recurrent ventricular arrhythmia in ICD patients.

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.

Factors determining ICD implantation in drug therapy patients after termination of antiarrythmics versus implantable defibrillators trial.

Because of a significant survival benefit in the defibrillator arm of the Antiarrhythmics versus Implantable Defibrillator (AVID) Trial, patients in the antiarrhythmic drug (AAD) arm were advised to undergo ICD implantation. Despite this recommendation, ICD implantation in AAD patients was variable, with a large number of patients not undergoing ICD implantation. Patients were grouped by those who had been on AAD < 1 year (n = 111) and those on AAD > 1 year (n = 223). Multiple clinical and socioeconomic factors were evaluated to identify those who might be associated with a decision to implant an ICD. The primary reason for patients not undergoing ICD implantation was collected, as well as reasons for a delayed implantation, occurring later than 3 months from study termination. Of 111 patients on AAD for less than 1 year, 53 received an ICD within 3 months compared to 40/223 patients on AAD for more than 1 year (P < 0.001). Patient refusal was the most common reason to not implant an ICD in patients on drug < 1 year; physician recommendation against implantation was the most common in patients on drug > 1 year. Multivariate analysis showed ICD recipients on AAD < 1 year were more likely to be working and have a history of myocardial infarction (MI), while those on AAD > 1 year were more likely to be working, have a history of MI and ventricular fibrillation, and less likely to have experienced syncope, as compared to those who did not get an ICD. Having private insurance may have played a role in younger patients receiving an ICD.