Apixaban for Stroke Prevention in Subclinical Atrial Fibrillation.

BACKGROUND: Subclinical atrial fibrillation is short-lasting and asymptomatic and can usually be detected only by long-term continuous monitoring with pacemakers or defibrillators. Subclinical atrial fibrillation is associated with an increased risk of stroke by a factor of 2.5; however, treatment with oral anticoagulation is of uncertain benefit. METHODS: We conducted a trial involving patients with subclinical atrial fibrillation lasting 6 minutes to 24 hours. Patients were randomly assigned in a double-blind, double-dummy design to receive apixaban at a dose of 5 mg twice daily (2.5 mg twice daily when indicated) or aspirin at a dose of 81 mg daily. The trial medication was discontinued and anticoagulation started if subclinical atrial fibrillation lasting more than 24 hours or clinical atrial fibrillation developed. The primary efficacy outcome, stroke or systemic embolism, was assessed in the intention-to-treat population (all the patients who had undergone randomization); the primary safety outcome, major bleeding, was assessed in the on-treatment population (all the patients who had undergone randomization and received at least one dose of the assigned trial drug, with follow-up censored 5 days after permanent discontinuation of trial medication for any reason). RESULTS: We included 4012 patients with a mean (±SD) age of 76.8±7.6 years and a mean CHA2DS2-VASc score of 3.9±1.1 (scores range from 0 to 9, with higher scores indicating a higher risk of stroke); 36.1% of the patients were women. After a mean follow-up of 3.5±1.8 years, stroke or systemic embolism occurred in 55 patients in the apixaban group (0.78% per patient-year) and in 86 patients in the aspirin group (1.24% per patient-year) (hazard ratio, 0.63; 95% confidence interval [CI], 0.45 to 0.88; P = 0.007). In the on-treatment population, the rate of major bleeding was 1.71% per patient-year in the apixaban group and 0.94% per patient-year in the aspirin group (hazard ratio, 1.80; 95% CI, 1.26 to 2.57; P = 0.001). Fatal bleeding occurred in 5 patients in the apixaban group and 8 patients in the aspirin group. CONCLUSIONS: Among patients with subclinical atrial fibrillation, apixaban resulted in a lower risk of stroke or systemic embolism than aspirin but a higher risk of major bleeding. (Funded by the Canadian Institutes of Health Research and others; ARTESIA ClinicalTrials.gov number, NCT01938248.).

Effectiveness of dual external direct current cardioversion for initial cardioversion in atrial fibrillation.

INTRODUCTION: Dual external direct current cardioversion (dual-DCCV) is a rhythm control strategy for persistent atrial fibrillation (AF), involving simultaneous delivery of two shocks from two defibrillators. The long-term effectiveness of this approach has not been studied in the biphasic cardioversion era. METHODS: Seventy-seven consecutive patients at a single center were identified to receive dual-DCCV at the time of their initial cardioversion for AF, when maximum output standard external direct current cardioversion failed in two vectors. Logistic regression was used to analyze risk factors for dual-DCCV in a historical control group of 77 patients undergoing standard cardioversion and Cox proportional hazard models were used to compare time to AF recurrence. RESULTS: The dual-DCCV group had a significantly larger body mass index (BMI), but similar AF duration and left atrial size as controls. Multivariable logistic regression revealed that BMI and absence of prior paroxysmal AF were risk factors for dual-DCCV (P < 0.05). There was no difference observed between dual-DCCV and control groups (adjusted hazard ratio = 0.57; P = .12) after adjusting for number of shocks and age. Transient hypoxia was the only acute complication in either group (P > .999). CONCLUSION: Dual-DCCV appears to be a safe and effective cardioversion strategy for patients with AF. The need for dual-DCCV in the treatment of AF appears to be influenced more by body habitus than atrial substrate.

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.