Botulinum toxin

Atrial fibrillation after cardiac surgery is an important issue. It prolongs hospital stay and requires anticoagulant therapy. A preliminary study showed that injecting botulinum toxin into the surrounding fat pad after bypass surgery may prevent postoperative atrial fibrillation. Dr. Evgeny Pokushalov (Institute of National Pathology, Novosibirsk, Russia) reported the study at the annual meeting of the American Heart Rhythm Society in 2014.

Summary of the study Atrial fibrillation occurs in 30% to 50% of patients undergoing cardiac surgery and usually occurs within 5 days after surgery. However, there are not many treatment options available. The guideline recommends the use of beta-blockers, but many treatments have Uncertainty, and may affect hemodynamic stability.

Evidence shows that the autonomic nervous system plays a role in the occurrence of atrial fibrillation, and ablation of an epicardial fat pad with a rich neural network can suppress arrhythmias. In an animal model, botulinum toxin injection into the fat pad temporarily inhibits atrial fibrillation.

Pokushalov and colleagues randomized 60 patients undergoing CABG surgery to the botulinum toxin group and the placebo group. The former injected botulinum toxin a (Xeomin) 50 U/mL in 4 epicardial fat pads, and the latter injected 0.9% NaCl 1ml. All patients had no paroxysmal atrial fibrillation, no cardiac surgery, or a history of ablation prior to surgery. ECG telemetry was continued at the time of hospitalization and ECG examination and 24-hour Holter recording were performed at 7, 14, 21, and 30 days, respectively. Both groups received the same number of saphenous and internal mammary artery grafts during surgery. There was no difference between the time of withdrawal of ventilator, the time of extubation, and the time of transfer out of the intensive care unit after surgery; similarly, there was no difference in CK-MB levels between the two groups after 1, 8, 16 or 24 hours after cardiopulmonary bypass.

Patients who received botulinum toxin type A had a lower incidence of atrial tachyarrhythmias (atrial fibrillation, atrial flutter, and atrial tachycardia) 30 days after surgery compared with placebo (injected saline). 7%ve.30%, P=0.024).

Botulinum toxin treatment had no complications, no congestive heart failure, myocardial infarction, stroke, and death; other outcomes did not differ between the two groups.

The investigators analyzed the limitations of this study, including the small sample size, excluding patients with preoperative atrial fibrillation, and the uncertainty of the long-term efficacy of botulinum toxin in maintaining sinus rhythm.

Pokushalov said that the study is "very encouraging" and we need to further evaluate the effect of botulinum toxin injected into the epicardial fat pad on postoperative atrial fibrillation. If a large multicenter investigator can demonstrate its efficacy, I am very confident that this treatment can be the gold standard for open heart surgery.

Dr. John Day, executive chairman of the 2014 HRS annual meeting (electrical physiology expert at the Mountain Arrhythmia Association, Utah, USA) believes that this is an interesting study, but the long-term efficacy and potential adverse consequences of the above treatments have not yet been resolved. That is, the efficacy of botulinum toxin is very good, which can quickly reduce the incidence of perioperative atrial fibrillation, but its efficacy may be short-lived.

Dr. Hugh Calkins, outgoing president of the HRS (Director of the Department of Arrhythmia at Johns Hopkins Hospital) pointed out that if further confirmation of the effectiveness and safety of this treatment, it will reduce the atrial fibrillation by 75%, I think this is a A very effective strategy can be used for all patients undergoing bypass surgery. Obviously this is a proof of concept, but further research is needed, more extensive trials are needed, more patients and more data are needed. In addition, the cost-effectiveness of this treatment is also a factor worth considering.