As the use of electroconvulsive therapy (ECT) increases, the chance of a practitioner's encountering a patient with significant heart failure, ventricular dysfunction, or valvular heart disease also increases. This article reviews the epidemiology, pathophysiology, and available data on the risk of ECT in these patients. Recommendations are made regarding evaluation and treatment of such patients. Some special situations are identified that may require a modification of routine procedures. Overall, ECT can be performed safely in most patients with underlying cardiac conditions, as long as appropriate precautions are taken to identify these patients ahead of time.