abnormal heart rhythm

Patients at risk of an abnormal heart rhythm after heart surgery were injected with botulinum toxin, and researchers assessed the effects over three years.

Up to 50% of patients can have an abnormal heart rhythm following heart surgery. In atrial fibrillation, a cause ofabnormal heart rhythm, the electrical impulses do not travel properly aroundthe heart. The resulting effect is an erratic rhythm that can cause weakness,and shortness of breath. It can make stroke and heart failure more likely.

Researchers from Russia hypothesized that the injection of botulinum toxin around the heart would reset the electrical impulses and prevent atrial fibrillation following surgery. Botulinum toxin is more familiar to us as botox, the injection that is given to smooth the appearance of wrinkles. It essentially works by blocking the messages that nerves send to muscles to make them do work. By blocking the messages from nerves around the heart, the researchers set out to see if the abnormal heart rhythm could be prevented.

Results from 60 patients undergoing coronary artery bypass surgery were collected. All patients were fitted with a medical implant that monitors and records the heart rhythm. Half of the patients were injected with botulinum toxin into fat pads surrounding the heart, and their data were compared with the other half of the patients who did not receive the injection. The data were analysed with the support of tw research programs in the USA, and published in Heart Rhythm.

The analysis of the heart rhythms showedthat the botulinum toxin injection prevented the development of atrial fibrillation in significantly more patients than the group who did not receiveit. The surprising finding for the researchers was that the effect lasted up to3 years. At this time point, only 23% of patients who had botulinum toxin hadan abnormal heart rhythm compared with 50% in the group without the injection.

The researchers reflect that maybe the botulinum toxin creates such a long-lasting effect by actually resetting theelectrical impulses within the heart. In general, botulinum toxin should onlylast a matter of months. They describe that a vicious cycle that oftenperpetuates the abnormal heart rhythm may be broken following the injection,and then once the heart is in a normal rhythm it does not come back.

The researchers caution, however, that this is the first study assessing the use of botulinum toxin in this way and larger clinical trials are necessary to ensure the results they obtained are solid.

Written by Nicola Cribb, VetMB DVSc Dip.ACVS

Reference: Romanov A, Pokushalov E, Ponomarev D, et al. Long-term suppression of atrial fibrillation by botulinum toxin injection into epicardia lfat pads in patients undergoing cardiac surgery: Three-year follow-up of a randomized study. Heart Rhythm. 2018.doi:10.1016/j.hrthm.2018.08.019.

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