Factors predicting maintenance of sinus rhythm after direct current cardioversion of atrial fibrillation and flutter: a reanalysis with recently acquired data.

A prospective study was conducted to evaluate how many patients maintain normal sinus rhythm after direct current (DC) cardioversion of atrial arrhythmias and to assess factors predictive of long-term success. The study group consisted of 61 patients (45 men) aged 18-88 years (mean age 66 +/- 11 years) who underwent cardioversion at our department from October 1990 to June 1992. Prior to cardioversion, the patients' medical history, medications, heart size on chest X ray, and echocardiographic findings were reviewed. Overall, 41 (67.2%) patients were in atrial fibrillation, while 20 (32.8%) had atrial flutter. Only 15% of the patients had valvular heart disease. 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 patients with an arrhythmia for less than 1 week (94.4%) compared to those with a 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 protocol aimed at following up the patients for 1 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 the 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 patients with an arrhythmia for less than 1 week prior to cardioversion in comparison to those with a longer or unknown duration (p = 0.11). Thus, in contrast to previous reports, according to these recent data on a patient population with a low prevalence of valvular heart disease, DC cardioversion can be attempted in most patients with atrial tachyarrhythmias. Clinical factors, heart size on chest X ray and echocardiographic findings should, however, be considered before deciding to perform DC cardioversion.