Long-term suppression of atrial fibrillation by botulinum toxin injection into epicardial fat pads in patients undergoing cardiac surgery: Three-year follow-up of a randomized study.

[BACKGROUND] Botulinum toxin (BTX) injections into epicardial fat pads in patients undergoing coronary artery bypass grafting (CABG) has resulted in suppression of atrial fibrillation (AF) during the early postoperative period through 1-year of follow-up in a pilot program.

[OBJECTIVE] The purpose of this study was to report 3-year AF patterns by the use of implantable cardiac monitors (ICMs).

[METHODS] Sixty patients with a history of paroxysmal AF and indications for CABG were randomized 1:1 to either BTX or placebo injections into 4 posterior epicardial fat pads. All patients received an ICM with regular follow-up for 3 years after surgery. The primary end point of the extended follow-up period was incidence of any atrial tachyarrhythmia after 30 days of procedure until 36 months on no antiarrhythmic drugs. The secondary end points included clinical events and AF burden.

[RESULTS] At the end of 36 months, the incidence of any atrial tachyarrhythmia was 23.3% in the BTX group vs 50% in the placebo group (hazard ratio 0.36; 95% confidence interval 0.14-0.88; P = .02). AF burden at 12, 24, and 36 months was significantly lower in the BTX group than in the placebo group: 0.22% vs 1.88% (P = .003), 1.6% vs 9.5% (P < .001), and 1.3% vs 6.9% (P = .007), respectively. In the BTX group, 2 patients (7%) were hospitalized during follow-up compared with 10 (33%) in the placebo group (P = .02).

[CONCLUSION] Injection of BTX into epicardial fat pads in patients undergoing CABG resulted in a sustained and substantial reduction in atrial tachyarrhythmia incidence and burden during 3-year follow-up, accompanied by reduction in hospitalizations.