Among patients with persistent atrial fibrillation, we found no reduction in the rate of recurrent atrial fibrillation when either linear ablation or ablation of complex fractionated electrograms was performed in addition to pulmonary-vein isolation. (Funded by St. Jude Medical; ClinicalTrials.gov number, NCT01203748.).

Background-Ventricular fibrillation is the main mechanism of sudden cardiac death. The feasibility of eliminating recurrent episodes by catheter ablation has not been reported. Methods and Results-Twenty-seven patients without known heart disease (13 men, 14 women, 41Ϯ14 years of age) were studied after being resuscitated from recurrent (10Ϯ12) episodes of primary idiopathic ventricular fibrillation; 23 had received a defibrillator. The first initiating beat of ventricular fibrillation had an identical electrocardiographic morphology and coupling interval (297Ϯ41 ms) to preceding isolated premature beats typically noted in the aftermath of resuscitation. These triggers were localized by mapping the earliest electrical activity and ablated by local radiofrequency delivery. Outcome was assessed by Holter and defibrillator memory interrogation. Premature beats were elicited from the Purkinje conducting system in 23 patients: from the left ventricular septum in 10, from the anterior right ventricle in 9, and from both in 4. The interval from the Purkinje potential to the following myocardial activation varied from 10 to 150 ms during premature beat but was 11Ϯ5 ms during sinus rhythm, indicating location at peripheral Purkinje arborization. The premature beats originated from the right ventricular outflow tract muscle in 4 patients. The accuracy of mapping was confirmed by acute elimination of premature beats during local radiofrequency delivery. During a follow-up of 24Ϯ28 months, 24 patients (89%) had no recurrence of ventricular fibrillation without drug. Conclusions-Primary idiopathic ventricular fibrillation is a syndrome characterized by dominant triggers from the distal Purkinje system. These sources can be eliminated by focal energy delivery.

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, 51.1Ϯ11.1 years) were enrolled and randomized to ablation (nϭ53) or "new" antiarrhythmic drugs alone or in combination (nϭ59). Crossover from the antiarrhythmic drugs and ablation groups occurred in 37 (63%) and 5 patients (9%), respectively (Pϭ0.0001). 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 (PϽ0.0001). 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.)

Triggers from the Purkinje arborization or the right ventricular outflow tract have a crucial role in initiating ventricular fibrillation associated with the long-QT and Brugada syndromes. These can be eliminated by focal radiofrequency ablation.

Background-This study aimed to determine 5-year efficacy of catheter ablation for persistent atrial fibrillation (AF) using AF termination as a procedural end point. Methods and Results-One hundred fifty patients (57±10 years) underwent persistent AF ablation using a stepwise ablation approach (pulmonary vein isolation, electrogram-guided, and linear ablation) with the desired procedural end point being AF termination. Repeat ablation was performed for recurrent AF or atrial tachycardia. AF was terminated by ablation in 120 patients (80%). Arrhythmia-free survival rates after a single procedure were 35.3%±3.9%, 28.0%±3.7%, and 16.8%±3.2% at 1, 2, and 5 years, respectively. Arrhythmia-free survival rates after the last procedure (mean 2.1±1.0 procedures) were 89.7%±2.5%, 79.8%±3.4%, and 62.9%±4.5%, at 1, 2, and 5 years, respectively. During a median follow-up of 58 (interquartile range, 43-73) months after the last ablation procedure, 97 of 150 (64.7%) patients remained in sinus rhythm without antiarrhythmic drugs. Another 14 (9.3%) patients maintained sinus rhythm after reinitiation of antiarrhythmic drugs, and an additional 15 (10.0%) patients regressed to paroxysmal recurrences only. Failure to terminate AF during the index procedure (hazard ratio 3.831; 95% confidence interval, 2.070-7.143; P<0.001), left atrial diameter ≥50 mm (hazard ratio 2.083; 95% confidence interval, 1.078-4.016; P=0.03), continuous AF duration ≥18 months (hazard ratio 1.984; 95% confidence interval, 1.024-3.846; P<0.04), and structural heart disease (hazard ratio 1.874; 95% confidence interval, 1.037-3.388; P=0.04) predicted arrhythmia recurrence. Conclusions-In patients with persistent AF, an ablation strategy aiming at AF termination is associated with freedom from arrhythmia recurrence in the majority of patients over a 5-year follow-up period. Procedural AF nontermination and specific baseline factors predict long-term outcome after ablation. (Circ Arrhythm Electrophysiol. 2015;8:18-24.

Background-This prospective clinical study evaluates the feasibility and efficacy of combined linear mitral isthmus ablation and pulmonary vein (PV) isolation in patients with paroxysmal atrial fibrillation (AF). Methods and Results-One hundred consecutive patients (13 women; age 55Ϯ10 years) with drug-refractory, symptomatic paroxysmal AF underwent PV isolation and linear ablation of the cavotricuspid isthmus and the mitral isthmus (lateral mitral annulus to the left inferior PV). They were compared with 100 consecutive patients (14 women; age, 52Ϯ10 years) undergoing PV isolation and cavotricuspid ablation without mitral isthmus ablation. Bidirectional mitral isthmus block was confirmed by demonstrating (1) a parallel corridor of double potentials during coronary sinus (CS) pacing, (2) an activation detour by pacing either side of the line, and (3) differential pacing techniques. Isolation of all PVs and cavotricuspid isthmus ablation were performed successfully in all. Mitral isthmus block was achieved in 92 patients after 20Ϯ10 minutes of endocardial radiofrequency application and an additional 5Ϯ4 minutes of epicardial radiofrequency application from within the CS in 68, resulting in a conduction delay of 151Ϯ26 ms during CS pacing. Thirty-two patients with mitral isthmus ablation compared with 49 without had recurrent atrial arrhythmia (Pϭ0.02) requiring further ablation. At 1 year after the last procedure, 87 patients with mitral isthmus ablation and 69 without (Pϭ0.002) were arrhythmia free without antiarrhythmic drugs, mitral isthmus ablation being the only factor associated with long-term success (RR for AF recurrence, 0.2; CI, 0.1 to 0.4; PϽ0.001). Conclusions-Catheter ablation of the mitral isthmus results consistently in demonstrable conduction block and is associated with a high cure rate for paroxysmal AF.

Background-Isolated atrial fibrillation (AF) is associated with mild enlargement of the left atrium (LA) and left ventricular (LV) diastolic dysfunction. The impact of ablation of isolated AF on left chamber size and function is unclear, and whether diastolic dysfunction is the cause or the consequence of AF remains unknown. The objective of this prospective study was to evaluate the impact of sinus rhythm restoration by catheter ablation on LV diastolic dysfunction, LA morphology, and mechanical function. Methods and Results-Forty-eight patients with isolated AF were studied by serial echocardiographic studies at baseline and at 1-, 3-, 6-, 9-, and 12-month intervals after radiofrequency ablation. LA dimensions and mechanical function and LV systolic and diastolic functions were evaluated at each time interval. Diastolic function was assessed with conventional Doppler parameters and new indexes such as tissue Doppler imaging, mitral flow propagation velocity, and combined criteria. LV diastolic dysfunction was present in paroxysmal and chronic AF patients with a reduction of tissue Doppler imaging lateral early diastolic peak velocity in 37% (PϽ0.001) and 48% (PϽ0.01), respectively, compared with healthy control subjects. At the end of the follow-up, LA area decreased significantly by 18% (PϽ0.001) in paroxysmal and 23% (PϽ0.05) in chronic AF patients. Diastolic function improved significantly with an increase in lateral early diastolic peak velocity of 29% (PϽ0.001) in paroxysmal AF and 46% (PϽ0.05) in chronic AF patients. A significant increase in LV ejection fraction was also noted for both groups: 7.7% and 18.8%, respectively. Conclusions-This study demonstrates reverse morphological remodeling of the LA and improvement of LV diastolic and systolic functions after restoration of sinus rhythm by ablation for isolated AF. Because patients with isolated AF have none of the traditional causes of LV diastolic dysfunction, our findings suggest that AF may be partly the cause rather than the consequence of diastolic dysfunction.

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