Ephedrine Increases Ventricular Arrhythmias in Conscious Dogs After Myocardial Infarction

The sympathomimetic amine, ephedrine, is used to augment physical performance and as a weight loss aid, but little is known about the cardiovascular consequences in individuals with ischemic heart disease.To assess the effects of ephedrine on cardiac autonomic control, baroreceptor reflex sensitivity (BRS), heart rate (HR) variability, HR response to acute myocardial ischemia, and resting catecholamines were measured before and after ephedrine in dogs with a prior myocardial infarction at low risk for sudden death. Nine of 15 animals had increased ventricular arrhythmias during ephedrine treatment (p = 0.01) and four had VF. Three dogs that had VF could not be resuscitated. Ephedrine increases ischemia-dependent arrhythmias at doses recommended in over-the-counter preparations. Increased arrhythmia risk was associated with augmented ischemia-dependent sympathetic reflex activation.