[Factors predicting long-term success of DC cardioversion of atrial arrhythmias.]

A prospective study was conducted to evaluate how many patients maintain sinus rhythm after DC cardioversion of atrial arrhythmias and to assess factors predictive of long-term success. The study group consisted of 61 patients (45 men, 16 women) aged 18-88 years (mean age 66 +/- 11 years) who undervent cardioversion, at the Department of Cardiology, Landspitalinn, from October 1990 to June 1992. Prior to cardioversion data were collected on the patient's medical history, medications, heart size on chest X-ray, and echocardiographic findings. Overall, 41 (67.2%) patients were in atrial fibrillation while 20 (32.8%) had atrial flutter. Sinus rhythm was restored by DC cardioversion in 47 (77%) patients, none of whom experienced an embolic event prior to discharge. Patients with atrial flutter had a higher conversion rate (95%) than those in atrial fibrillation (68.3%) (p=0.024) and also those who had had an atrial arrhythmia for less than one week (94.4%) in comparison to patients with an arrhythmia of longer or unknown duration (69.8%) (p-0.047). The primary success rate was not influenced by heart size on chest X-ray or echocardiographic variables. The study aimed to follow the patients for one year after cardioversion. Of the 47 patients who converted to sinus rhythm data are available on 44 for a mean follow-up of 11 +/- 3 months (range 1-14 months), at which time 25 (57%) still remained in sinus rhythm. Heart size on chest X-ray was significantly increased in the group that did not maintain sinus rhythm (p=0.03), and their left atrial size on echocardiography was slightly increased (p=0.10). Patients who originally had atrial flutter were more likely to remain in sinus rhythm than those who had been in atrial fibrillation (p=0.12), as did those who had had the arrhythmia for less than one week prior to cardioversion compared to those who had a longer or unknown duration (p=0.11). We conclude, that DC cardioversion can be attempted in most patients with atrial flutter or fibrillation. However, clinical factors, heart size on chest X-ray and echocardiographic findings should be considered before deciding to perform DC cardioversion.