BOSTON – A single set of four injections with botulinum toxin into neuron-containing cardiac fat pads of patients during open-chest cardiac artery bypass surgery led to a long-term cut in the cumulative incidence of atrial tachyarrhythmias during 3-year follow-up in a pilot, sham-controlled study with 60 patients at two Russian centers.
“Because the favorable reduction of atrial fibrillation [AF] outlasted the anticipated botulinum toxin effects on autonomic nervous system activity, this may represent a form of autonomic reverse remodeling” triggered by just one injection of the paralyzing toxin at each of four intracardiac fat pads,, said at the annual scientific sessions of the Heart Rhythm Society. Botulinum toxin (BT) blocks neuronal release of acetylcholine, thereby interfering with cholinergic neurotransmission and producing hypothesized neurologic remodeling, explained Dr. Romanov, a researcher at the in Novosibirsk, Russia.
The 3-year results also showed statistically significant differences or trends favoring BT injections for several other clinical outcomes. Two deaths and two strokes occurred, all among the control patients. Two patients required a total of three hospitalizations during follow-up in the BT-treated group, compared with 10 patients hospitalized a total of 21 times in the control arm. Clinicians prescribed antiarrhythmic drugs to six of the BT-treated patients and to 15 of the controls.
All patients received an implanted heart rhythm monitor during their bypass surgery, and the researchers measured AF burden – the percentage of time during which AF occurred. After 12 months, 24 months, and 36 months, the AF burden averaged 0.2%, 1.6%, and 1.2%, respectively, in the BT-treated patients and 1.9%, 9.5%, and 6.9% in the sham-control patients.
“We don’t know why this works, but it’s a fascinating new approach that is worthy of further study,” commented
“This is an extremely exciting study, but it remains inconclusive because how it works is not fully understood,” commented , professor and chief of cardiology at the University of British Columbia in Vancouver.