An Evaluation of Dc Shock Treatment of Atrial Arrhythmias

Abstract A total of 1098 DC shocks were given in 572 attempts at reversion of permanent atrial arrhythmias in 437 patients. Of these, 348 (80%) reverted to sinus rhythm during the first attempt. Complications of the DC shock itself were infrequent. Ventricular arrhythmias and bradycardia occurred, usually of short duration. Eight patients developed ventricular fibrillation, and in one instance the episode was dramatic. Digitalis toxicity disposed patients to some of the ventricular arrhythmias. No deaths, considered due to the DC shock, were observed. Thirteen patients (3%) developed an embolic episode 6 hours‐6 days after reversion. Only two of these were among the 228 patients who were on anticoagulant therapy, as against 11 among the 209 who were not. Quinidine syncope, caused by ventricular fibrillation, was observed in eight patients. The 290 patients first treated were followed up after the first attempt at reversion until relapse of the atrial arrhythmia or for a minimum of two years. After this period, 23% of the patients treated were in sinus rhythm. The sinus rhythm attained was most stable in the patients with operated mitral stenosis, atrial septal defect and thyrotoxicosis that received treatment. The stability gradually decreased with increasing duration of the preceding arrhythmia, but was little influenced by the heart size and even less by functional classification. Good long‐term results were obtained in individual patients with all etiological and anatomical types of heart disease. Simple criteria can hardly be given for selection of patients who will benefit from reversion of atrial arrhythmia; and careful evaluation of the individual patient is required.