Botulinum toxin injection may ward off postop AFib

Injecting botulinum toxin injection into the epicardial fat pads prevented recurrences of atrial tachyarrhythmia in the postoperative period in patients with prior paroxysmal atrial fibrillation (PAF) undergoing coronary artery bypass grafting (CABG) surgery, according to results of a study presented at the Heart Rhythm Society meeting in San Francisco.

Another finding of this double-blind, randomized, placebo-controlled study was that the botulinum toxin injection did not alter timing of discharge from the ICU, postoperative hospital length of stay, or any other postoperative complication.

“In this study we did not see any minor or major complications after botulinum toxin injections in terms of effect on the cardiac contractility as well as systemic effect,” said study author Evgeny Pokushalov, MD, PhD, of the State Research Institute of Circulation Pathology in Novosibirsk, Russia. “The favorable effect of botulinum toxin injections in ganglionated plexi on occurrence of the postoperative AF was lasting at least 1 month after surgery.”

Patients were randomly assigned to botulinum toxin (n=30) or 0.9% normal saline (control; n=30) injection into epicardial fat pads using a coded envelope system opened on the day of the surgery. Patients were followed for 30 days to assess maintenance of sinus rhythm. All patients underwent conventional CABG. After the main stage of the surgery, botulinum toxin (50 U/1 mL at each fat pad; botulinum toxin group), or 0.9% normal saline (1 mL at each fat pad; placebo group) was injected into the entire visible area of the four major epicardial fat pads. In both treatment groups, any cardioversion during the follow-up was regarded as a failure for the efficacy end point.

Patients had daily 12-lead electrocardiograms and continuous telemetry monitoring while hospitalized. Rehospitalization and treatment for AF were monitored. Weekly ECGs and 24h Holter recordings were performed at 7, 14, 21, and 30 days. Holter and ECG interpretation was by consensus of 2 physicians blinded to the phase of the study (ie, baseline or follow-up) and assigned study treatment. Patients were instructed to report symptoms suggestive of AF and to undergo prompt ECG recording.

“AF is a common complication of cardiac surgery [10% to 50%],” said Dr Pokushalov. “Patients with postoperative AF were more likely to be diagnosed with minor as well as major complications [ie, stroke, MI, acute renal failure requiring dialysis, and sternum dehiscence]. Postoperative AF patients also had longer total length of hospital stay, and the stay in ICU can more than double.”

The difference in survival is also reflected in long-term survival, 5-year survival being 83% for postoperative AF patients and 93% for postoperative normal sinus rhythm patients, according to the study. In the vast majority, postoperative AF develops in the first few days after surgery, permanent ganglionated plexi destruction should not be the method of choice in patients with temporary risk factors

“Temporary autonomic blockade without permanent destruction of the ganglionated plexi during the postoperative period would be expected to produce favorable results in the short term, coinciding with postoperative risk of AF,” said Dr Pokushalov. “Our study strongly supports this hypothesis by utilizing a novel therapy. The transient ablative effects of botulinum toxin on the ganglionated plex--both cholinergic and adrenergic elements--coincides with the transient nature of postoperative AF.”