SAFETY OF HIGH-ENERGY INTERNAL CARDIOVERSION FOR ATRIAL-FIBRILLATION

High energy internal cardioversion has been proposed as an alternative method to cardiovert drug refractory or external cardioversion refrac tory atrial fibrillation. However, the safety of this technique has no t been clearly evaluated. We reviewed findings in 53 patients who unde rwent 55 sessions of high energy internal cardioversion (2 patients un derwent 2 sessions) for termination of longstanding atrial fibrillatio n. Shocks energy varied from 70-270 J. Three patients had 3 shocks dur ing the same session, 5 had 2, and 47 only 1. Success rate was 89% (su ccess was defined as immediate conversion to normal sinus rhythm). Low cardiac output occurred in two patients, and resulted in the death of one of these individuals, a patient with significant hypertrophic car diomyopathy and heart failure. The other patient recovered completely. In 11% of the cases, shock induced transient atrioventricular block, necessitating ventricular pacing until sinus rhythm was restored. in t hree patients, a moderate but asymptomatic and uncomplicated pericardi al effusion was diagnosed on echocardiogram. Finally, four patients ha d side effects related to venous puncture, which resolved spontaneousl y. These results suggest that high energy internal cardioversion is ef fective for conversion of atrial fibrillation. However, the technique may not be optimal in patients with advanced hypertrophic cardiomyopat hy and in such cases the technique should be used carefully and only i n the case of failure of external cardioversion; no more than two shoc ks should be delivered during the same procedure. Temporary ventricula r pacing should be provided in all patients and an echocardiogram shou ld be performed before patients are being discharged.