The Feasibility and Beneficial Effects of Atrial Pacing in Sick Sinus Syndrome

Abstract

The number of patients with sick sinus syndrome (SSS) who have been treated by permanent pacemaker implant has been increasing. But, the percentage of those undergoing atrial pacing is still relatively low because of the fear that these patients could later develop atrioventricular conduction disturbances. The purpose of the present study is to examine the hemodynamic effects of atrial contraction, atrioventricular conductivity and progression to chronic atrial fibrillation, and then to discuss the feasibility and beneficial effects of atrial pacing in SSS. Clinical observations and experimental studies have indicated that, when atrial contraction occurs during ventricular systole, cardiac output and ventricular systolic pressure decrease and atrial pressure increase more than when atrioventricular synchrony is maintained. There was no observed association with second or third degree atrioventricular block in 68 sick sinus patients during follow-up, in spite of some abnormalities in the electrophysiological study. Eleven patients out of 35 (31.4%) who had been paced via the ventricule showed atrial fibrillation, whereas only one out of 15 (6.7%) of those who received atrial pacemakers progressed to atrial fibrillation. These results suggest that SSS is rarely associated with atrioventricular block and that atrial pacing has beneficial effects on hemodynamics and prevention of atrial fibrillation. In conclusion, permanent atrial pacing should be chosen for pacemaker treatment of SSS.