Vagal Stimulation for Heart Diseases: From Animals to Men

– An Example of Translational Cardiology –

Abstract

An autonomic imbalance with a reduction in vagal activity and an increase in sympathetic activity is present in heart failure. The same type of imbalance, when present in patients with a myocardial infarction, is associated with increased risk for cardiac mortality. Experimental studies have demonstrated that vagal stimulation has an antifibrillatory effect and has proven to be beneficial in animal models of heart failure. Given this background, the potential value of chronic vagal stimulation was explored in humans with an implantable neuro-stimulator capable of delivering low current pulses with adjustable parameters to stimulate the right vagus. A small multicenter feasibility and safety study exploring efficacy has recently been completed. A total of 32 patients with left ventricular ejection fraction (LVEF) <35% and a history of chronic heart failure in symptomatic NYHA class II-III were included in the study. The results indicate feasibility and safety. Interestingly, there are also very encouraging results for the efficacy on the NYHA class, quality of life, 6-min walk test, left ventricular end-systolic volume and LVEF. The latter, at the 1-year follow up, had increased from 21±7% to 34±12% (P<0.0001). Finally, vagal stimulation in heart failure patients has a strong rationale and the preliminary data suggests that it is likely to be of value to these patients. It is now appropriate to move toward a randomized controlled clinical trial of adequate size. (Circ J 2011; 75: 20-27)