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Botulinum toxin suppression of AF maintained at 3 years
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BOSTON — Patients who received an injection of botulinum toxin into epicardial fat pads during CABG had lower incidence of atrial tachyarrhythmias and reduced atrial fibrillation burden at 3 years vs. placebo, researchers reported at the Heart Rhythm Society Annual Scientific Sessions.
As Cardiology Today previously reported, when researchers randomly assigned 60 patients (mean age, 63 years; 20% women) with paroxysmal AF and an indication for CABG to an injection of botulinum toxin (Xeomin, Merz Pharmaceuticals) 50 U/1 mL at each fat pad or placebo (0.9% normal saline, 1 mL at each fat pad) during surgery, the botulinum toxin group had less AF recurrence and burden at 1 year.
In a presentation here, Alexander Romanov, MD, PhD, FHRS, from the E. Meshalkin National Medical Research Center of the Ministry of Health of the Russian Federation in Novosibirsk, Russia, said the results were sustained out to 3 years, despite the botulinum toxin having long disappeared from patients’ systems.
“Botulinum toxin can be viewed as a neuromodulator, and thus differs from the neurodestructive effects of other therapeutic efforts,” Romanov said during the presentation. “Because the favorable reduction of atrial fibrillation outlasted the anticipated botulinum toxin effect on the autonomic nervous system activity, this may represent a form of autonomic reverse remodeling.”
Botulinum toxin is also used for facial injections and to treat muscle stiffness/spasms and migraines.
At 3 years, the primary endpoint of any atrial tachyarrhythmia including AF with a monthly burden exceeding 0.5% without use of antiarrhythmic drugs occurred in 23% of the botulinum toxin group vs. 50% of the placebo group (HR = 0.36; 95% CI, 0.14-0.88), according to the researchers.
The botulinum toxin group also had fewer patients hospitalized (P = .02), fewer total hospitalizations (P < .001) and less antiarrhythmic drug use (P = .029) vs. the placebo group, Romanov said, noting there were also trends that favored the botulinum group for new endocardial AF ablation, thrombo-embolic events and death, but these did not reach statistical significance.
Also at 3 years, AF burden was 1.3% in the botulinum toxin group vs. 6.9% in the placebo group (P = .007), he said.
A larger study, sponsored by Allergan, has been commenced to confirm the findings and will include patients undergoing valve surgery as well as those undergoing CABG, Romanov said. – by Erik Swain
Reference:
Romanov A, et al. LBCT02-01. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 9-12, 2018; Boston.
Disclosure: Romanov reports he serves on the speakers bureau for Biosense Webster, Boston Scientific and Medtronic and receives research grants from Biosense Webster, Boston Scientific, EP Dynamics and Spectrum Dynamics.
Perspective
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Daniel J. Cantillon, MD
This was an interesting study, albeit a small one, with 30 patients in each arm randomized to the concomitant use of botulinum toxin injected into the epicardial fat pads at the time of open-heart surgery vs. placebo. What the investigators found was a significant reduction in the presence of postoperative AF, and the benefit appeared to be sustained over an extended period of follow-up, longer than what would have been expected with the toxin itself. This suggests promise for the concept of neuromodulation as a treatment for AF. Other studies in the past have looked at neuromodulation strategies to treat atrial and ventricular arrhythmias, and there have been examples where it was successful, including the treatment of ventricular arrhythmias with stellate ganglia block. If the findings of this study are confirmed in subsequent studies, patients undergoing CABG may also benefit from concomitant delivery of this therapy. We know that up to 25% of patients who undergo CABG experience postoperative AF.
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