In patients with atrial fibrillation and congestive heart failure, a routine strategy of rhythm control does not reduce the rate of death from cardiovascular causes, as compared with a rate-control strategy. (ClinicalTrials.gov number, NCT00597077.)

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Background: Advanced generation ablation technologies have been developed to achieve more effective pulmonary vein isolation (PVI) and minimize arrhythmia recurrence after atrial fibrillation (AF) ablation. Methods: We randomly assigned 346 patients with drug-refractory paroxysmal AF to contact force–guided radiofrequency ablation (CF-RF; n=115), 4-minute cryoballoon ablation (Cryo-4; n=115), or 2-minute cryoballoon ablation (Cryo-2; n=116). Follow-up was 12 months. The primary outcome was time to first documented recurrence of symptomatic or asymptomatic atrial tachyarrhythmia (AF, atrial flutter, or atrial tachycardia) between days 91 and 365 after ablation or a repeat ablation procedure at any time. Secondary end points included freedom from symptomatic arrhythmia and AF burden. All patients received an implantable loop recorder. Results: One-year freedom from atrial tachyarrhythmia defined by continuous rhythm monitoring was 53.9%, 52.2%, and 51.7% with CF-RF, Cryo-4, and Cryo-2, respectively ( P =0.87). One-year freedom from symptomatic atrial tachyarrhythmia defined by continuous rhythm monitoring was 79.1%, 78.2%, and 73.3% with CF-RF, Cryo-4, and Cryo-2, respectively ( P =0.26). Compared with the monitoring period before ablation, AF burden was reduced by a median of 99.3% (interquartile range, 67.8%–100.0%) with CF-RF, 99.9% (interquartile range, 65.3%–100.0%) with Cryo-4, and 98.4% (interquartile range, 56.2%–100.0%) with Cryo-2 ( P =0.36). Serious adverse events occurred in 3 patients (2.6%) in the CF-RF group, 6 patients (5.3%) in the Cryo-4 group, and 7 patients (6.0%) in the Cryo-2 group, with no significant difference between groups ( P =0.24). The CF-RF group had a significantly longer procedure duration but significantly shorter fluoroscopy exposure ( P <0.001 vs cryoballoon groups). Conclusions: In this multicenter, randomized, single-blinded trial, CF-RF and 2 different regimens of cryoballoon ablation resulted in no difference in 1-year efficacy, which was 53% by time to first recurrence but >98% burden reduction as assessed by continuous cardiac rhythm monitoring. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01913522.

AimsThis multicentre, randomized trial compared three strategies of AF ablation: ablation of complex fractionated electrograms (CFE) alone, pulmonary vein isolation (PVI) alone, and combined PVI + CFE ablation, using standardized automated mapping software.Methods and resultsPatients with drug-refractory, high-burden paroxysmal (episodes >6 h, >4 in 6 months) or persistent atrial fibrillation (AF) were enrolled at eight centres. Patients (n = 100) were randomized to one of three arms. For CFE alone (n = 34), spontaneous/induced AF was mapped using validated, automated CFE software and all sites <120 ms were ablated until AF termination/non-inducibility. For PVI (n = 32), all four PV antra were isolated and confirmed using a circular catheter. For PVI + CFE (n = 34), all four PV antra were isolated, followed by AF induction and ablation of all CFE sites until AF termination/non-inducibility. Patients were followed at 3, 6, and 12 months with a visit, ECG, 48 h Holter. Atrial fibrillation symptoms were confirmed by loop recording. Repeat procedures were allowed within the first 6 months. The primary endpoint was freedom from AF >30 s at 1 year. Patients (age 57 ± 10 years, LA size 42 ± 6 mm) were 35% persistent AF. In CFE, ablation terminated AF in 68%. Only 0.4 PVs per patient were isolated as a result of CFE. In PVI, 94% had all four PVs successfully isolated. In PVI + CFE, 94% had all four PVs isolated, 76% had inducible AF with additional CFE ablation, with 73% termination of AF. There were significantly more repeat procedures in the CFE arm (47%) vs. PVI (31%) or PVI + CFE (15%) (P = 0.01). After one procedure, PVI + CFE had a significantly higher freedom from AF (74%) compared with PVI (48%) and CFE (29%) (P = 0.004). After two procedures, PVI + CFE still had the highest success (88%) compared with PVI (68%) and CFE (38%) (P = 0.001). Ninety-six percent of these patients were off anti-arrhythmics. Complications were two tamponades, no PV stenosis, and no mortality.ConclusionIn high-burden paroxysmal/persistent AF, PVI + CFE has the highest freedom from AF vs. PVI or CFE alone after one or two procedures. Complex fractionated electrogram alone has the lowest one and two procedure success rates with a higher incidence of repeat procedures.ClinicalTrials.gov identifier number NCT00367757.

The STOP AF trial demonstrated that cryoballoon ablation is a safe and effective alternative to antiarrhythmic medication for the treatment of patients with symptomatic paroxysmal AF, for whom at least one antiarrhythmic drug has failed, with risks within accepted standards for ablation therapy. (A Clinical Study of the Arctic Front Cryoablation Balloon for the Treatment of Paroxysmal Atrial Fibrillation [Stop AF]; NCT00523978).

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Background-Adenosine acutely reconnects pulmonary veins (PVs) after radiofrequency application, revealing "dormant conduction" and identifying PVs at risk of reconnection, but the underlying mechanisms are unknown. Methods and Results-Canine PV and left-atrial (LA) action potentials were recorded with standard microelectrodes and ionic currents with whole-cell patch clamp before and after adenosine perfusion. PVs were isolated with radiofrequency current application in coronary-perfused LA-PV preparations. Adenosine abbreviated action potential duration similarly in PV and LA but significantly hyperpolarized resting potential (by 3.9Ϯ0.5%; PϽ0.05) and increased dV/dt max (by 34Ϯ10%) only in PV. Increased dV/dt max was not due to direct effects on I Na , which was reduced similarly by adenosine in LA and PV but correlated with resting-potential hyperpolarization (rϭ0.80). Adenosine induced larger inward rectifier K ϩ current (I KAdo ) in PV (eg, -2.28Ϯ0.04 pA/pF; -100 mV) versus LA (-1.28Ϯ0.16 pA/pF). Radiofrequency ablation isolated PVs by depolarizing resting potential to voltages positive to -60 mV. Adenosine restored conduction in 5 dormant PVs, which had significantly more negative resting potentials (-57Ϯ6 mV) versus nondormant (-46Ϯ5 mV, nϭ6; PϽ0.001) before adenosine. Adenosine hyperpolarized both, but more negative resting-potential values after adenosine in dormant PVs (-66Ϯ6 mV versus -56Ϯ6 mV in nondormant; PϽ0.001) were sufficient to restore excitability. Adenosine effects on resting potential and conduction reversed on washout. Spontaneous recovery of conduction occurring in dormant PVs after 30 to 60 minutes was predicted by the adenosine response. Key Words: arrhythmia ablation Ⅲ adenosine Ⅲ atrium Ⅲ conduction Ⅲ electrophysiology Ⅲ ion channels P ulmonary vein isolation (PVI) is an effective treatment for atrial fibrillation (AF). 1,2 Nevertheless, many patients require repeated ablation procedures because of AF recurrence, which in most cases are associated with reconnection of previously isolated PVs. 3,4 It has recently been noted that intravenous purinergic agonists such as adenosine can transiently restore conduction through a previously isolated PV, a phenomenon called "dormant conduction." [5][6][7][8] The demonstration of dormant conduction has predictive value for eventual reconnection, and additional radiofrequency (RF) applications to veins showing dormant conduction at the time of initial PVI may prevent reconnection and AF recurrence. 6 -8 The mechanisms by which adenosine restores conduction to dormant PVs are unknown. The objectives of this study were to (1) explore the effects of adenosine on ionic currents and action potentials (APs) in canine left-atrial (LA) and PV cardiomyocytes, and (2) relate these effects to changes in conduction between the PV and LA after RF ablation in an in vitro model. Conclusions-Adenosine Clinical Perspective on p 972 Materials and MethodsSee the online-only Data Supplement for the complete Materials and Methods section. The following text summarize...

The use of blanking periods, the immediate period postablation during which transient tachyarrhythmia episodes are not considered recurrences, has been predicated on the assumption that not all early recurrences of atrial tachyarrhythmias (ERAT) will lead to later recurrences and, as such, does not necessarily represent treatment failure. While ERAT can be expected to occur in approximately 38% of patients within the first 3 months of atrial fibrillation (AF) ablation, only half of these patients will manifest later recurrences. Clinical features related to the patient's history of AF, the index ablation procedure, and particularities of the ERAT can help identify patients at higher risk of later recurrence in whom aggressive attempts to control rhythm, including early cardioversion and reintervention, may be justified.