SINCE the introduction of synchronized direct-current shock by Lown,1 the electrical treatment of cardiac arrhythmias has become widespread. Despite reports of myocardial damage,2 embolization,3 fatal arrhythmias,4 digitalis intoxication,5 and pulmonary edema,6 the popularity of cardioversions has continued. It is now generally accepted that electrical shock is much safer than drugs.7,8 In addition, the initial conversion rate has been reported as 90%.7,8 This has made it appear that direct-current countershock offers a nearly complete solution to longstanding atrial fibrillation. The following study reports a series of cardioversions which were performed on patients with rheumatic mitral valvular disease and chronic atrial fibrillation. This affords the opportunity for a more critical appraisal of direct-current countershock.
Between January 1964 and August 1965, 100 cardioversions were performed on 67 patients at the University of Kansas Medical Center. All of the patients had mitral valvular rheumatic heart disease and chronic atrial fibrillation (at least of