Effects of physiologic pacing versus ventricular pacing on the risk of stroke and death due to cardiovascular causes

Background: Evidence suggests that physiologic pacing (dual-chamber or atri al) may be superior to single-chamber (ventricular) pacing because it is as sociated with lower risks of atrial fibrillation, stroke, and death. These benefits have not been evaluated in a large, randomized, controlled trial. Methods: At 32 Canadian centers, patients without chronic atrial fibrillati on who were scheduled for a first implantation of a pacemaker to treat symp tomatic bradycardia were eligible for enrollment. We randomly assigned pati ents to receive either a ventricular pacemaker or a physiologic pacemaker a nd followed them for an average of three years. The primary outcome was str oke or death due to cardiovascular causes. Secondary outcomes were death fr om any cause, atrial fibrillation, and hospitalization for heart failure. Results: A total of 1474 patients were randomly assigned to receive a ventr icular pacemaker and 1094 to receive a physiologic pacemaker. The annual ra te of stroke or death due to cardiovascular causes was 5.5 percent with ven tricular pacing, as compared with 4.9 percent with physiologic pacing (redu ction in relative risk, 9.4 percent; 95 percent confidence interval, -10.5 to 25.7 percent [the negative value indicates an increase in risk]; P = 0.3 3). The annual rate of atrial fibrillation was significantly lower among th e patients in the physiologic-pacing group (5.3 percent) than among those i n the ventricular-pacing group (6.6 percent), for a reduction in relative r isk of 18.0 percent (95 percent confidence interval, 0.3 to 32.6 percent; P = 0.05). The effect on the rate of atrial fibrillation was not apparent un til two years after implantation. The observed annual rates of death from a ll causes and of hospitalization for heart failure were lower among the pat ients with a physiologic pacemaker than among those with a ventricular pace maker, but not significantly so (annual rates of death, 6.6 percent with ve ntricular pacing and 6.3 percent with physiologic pacing; annual rates of h ospitalization for heart failure, 3.5 percent and 3.1 percent, respectively ). There were significantly more perioperative complications with physiolog ic pacing than with ventricular pacing (9.0 percent vs. 3.8 percent, P < 0. 001). Conclusions: Physiologic pacing provides little benefit over ventricular pa cing for the prevention of stroke or death due to cardiovascular causes. (N Engl J Med 2000;342:1385-91.) (C)2000, Massachusetts Medical Society.