Combined epicardial and endocardial ablation for atrial fibrillation: Best practices and guide to hybrid convergent procedures.

The absence of strategies to consistently and effectively address nonparoxysmal atrial fibrillation by nonpharmacological interventions has represented a long-standing treatment gap. A combined epicardial/endocardial ablation strategy, the hybrid Convergent procedure, was developed in response to this clinical need. A subxiphoid incision is used to access the pericardial space facilitating an epicardial ablation directed at isolation of the posterior wall of the left atrium. This is followed by an endocardial ablation to complete isolation of the pulmonary veins and for additional ablation as needed. Experience gained with the hybrid Convergent procedure during the last decade has led to the development and adoption of strategies to optimize the technique and mitigate risks. Additionally, a surgical and electrophysiology "team" approach including comprehensive training is believed critical to successfully develop the hybrid Convergent program. A recently completed randomized clinical trial indicated that this ablation strategy is superior to an endocardial-only approach for patients with persistent atrial fibrillation. In this review, we propose and describe best practice guidelines for hybrid Convergent ablation on the basis of a combination of published data, author consensus, and expert opinion. A summary of clinical outcomes, emerging evidence, and future perspectives is also given.

Wide complex tachycardia in a healthy young man.

We describe a case of a young man referred with a broad complex tachycardia for evaluation and ablation. Electrophysiological study was performed and revealed a left lateral accessory pathway with antegrade decremental conduction causing antidromic reciprocating re-entrant tachycardia. Ablation was successfully performed. Left lateral accessory pathways with decremental conduction are rarely encountered.

Left atrial linear lesions are required for successful treatment of persistent atrial fibrillation.

AIMS: This study evaluates the clinical outcome and incidence of left atrial (LA) macro re-entrant atrial tachycardia (AT) in patients in whom persistent atrial fibrillation (AF) terminated during catheter ablation without the need of roof and mitral lines. METHODS AND RESULTS: Persistent AF was terminated by ablation in 154 of 180 consecutive patients. AF history was 60 months including 11 months of continuous AF. Patients were divided into two groups: those who had not required both LA linear lesions to terminate AF (group A, 85 patients), and those who had (group B, 69 patients). There was no difference in clinical and echocardiographic characteristics between both groups except for a shorter duration of continuous AF in group A (9 vs.12 months, respectively) (P = 0.03). After 28 months of follow-up, the incidence of LA macro re-entrant AT necessitating linear ablation was higher in group A (76%) compared with group B (33%) (P = 0.002). When complete linear block could not be achieved during the index procedure, the incidence of subsequent roof (P = 0.008) or mitral isthmus (P = 0.010) dependent macro re-entrant AT was higher. CONCLUSION: Although persistent AF can be terminated by catheter ablation without linear lesions, the majority will require linear lesions for macro re-entrant AT.

Advances in mechanisms of atrial fibrillation: structural remodeling, high-frequency fractionated electrograms, and reentrant AF drivers.

The mechanisms to explain atrial fibrillation (AF) have been widely debated. Although contemporary experimental techniques have provided more insight, hypotheses regarding AF propagation conceived in the early half of the century remain minimally altered and relevant today. Modern mapping technologies have implicated multiwavelet reentry as the electrophysiologic basis to explain AF propagation within the atrial myocardium; however, reentry has also been observed within pulmonary veins and may behave as a focal trigger. The ability to terminate AF by catheter ablation has provided additional clues to explain AF induction and sustenance. The presence of complex fractionated electrograms (CFAE) and subsequent successful CFAE-directed ablation suggest that diseased atrial myocardium is a necessary substrate for AF maintenance. Atrial remodeling creates differential areas of refractory periods and conduction velocity, which, in turn, creates a suitable environment for AF. This review addresses the complex relationship between remodeled atrial myocardium and reentry and explores the role of CFAEs in AF maintenance.

Equivalent arrhythmic risk in patients recently diagnosed with dilated cardiomyopathy compared with patients diagnosed for 9 months or more.

BACKGROUND: The Centers for Medicare and Medicaid Services (CMS) recently expanded coverage for implantable cardioverter-defibrillators (ICDs) in patients with left ventricular ejection fraction < or =35% and nonischemic dilated cardiomyopathy for > or =9 months. To investigate the ramifications of these criteria, the ICD registry from Tufts-New England Medical Center was analyzed for arrhythmic events and death in patients with newly diagnosed (<9 months) vs late-diagnosed (> or =9 months) nonischemic dilated cardiomyopathy. OBJECTIVES: The purpose of this study was to analyze the arrhythmic risk in patients with recent vs late diagnosis of nonischemic dilated cardiomyopathy. METHODS: One hundred thirty-one patients with nonischemic dilated cardiomyopathy were divided into two cohorts (<9 or > or =9 months of symptoms) and analyzed for any occurrence of treated ventricular arrhythmia, potentially lethal arrhythmias defined as ventricular flutter rates > or =230 bpm, and ventricular fibrillation. Patients with documented sustained ventricular tachycardias (included in prior CMS coverage) were excluded. RESULTS: In the study group, the mean age was 58.1 +/- 15 years and ejection fraction 20.6% +/- 8%. In a follow-up period of 25.3 +/- 24 months, the 52 patients with a recent diagnosis (1.4 +/- 2 months) had no difference in the occurrence of ventricular arrhythmias (P = .49) and malignant ventricular arrhythmias (P = .16) compared with the 79 patients diagnosed > or =9 months (mean 58.1 +/- 39 months). CONCLUSION: Patients with nonischemic dilated cardiomyopathy experienced equivalent occurrences of treated and potentially lethal arrhythmias irrespective of diagnosis duration. These findings suggest that the 9-month time qualifier used in the CMS guidelines for ICD reimbursement may not reliably discriminate patients at high risk for sudden cardiac death in this selected population.