Significance of asymptomatic bradycardia for subsequent pacemaker implantation and mortality in patients >60 years of age

Abstract

Sinus bradycardia may be more significant in older patients than in a younger group because it could signal important or advanced conduction system and/or cardiac disease potentially modifiable with pacemaker implantation. We evaluated the clinical need for subsequent pacemaker implantation and mortality rate in outpatients >60 years of age with relatively asymptomatic bradycardia (heart rate <55 beats/min without a subsequent pacemaker implantation within 2 weeks) or not (heart rate 60 to 70 beats/min). The 2 groups were matched against pacemaker implantation and death records but without data on indication or cause. Kaplan-Meier survival curves and univariate and multivariable models examined pacemaker implantation and all-cause mortality. The cohort consisted of 470 patients with and 2,090 without asymptomatic bradycardia. Mean follow-up period was 7.2 ± 2.9 years during which 137 patients (5.4%) underwent pacemaker implantation and 748 (29.2%) died. Incidence of pacemaker placement was higher in the bradycardia cohort (9% vs 5%, p <0.001). The higher incidence of pacemaker implantation did not appear in the first 4 years. Univariate analysis showed no increase in mortality in the bradycardia group (hazard ratio 0.87, 95% confidence interval 0.72 to 1.04, p = 0.130), whereas multivariable analysis showed protection (hazard ratio 0.78, 95% confidence interval 0.65 to 0.94, p = 0.010). In conclusion, older patients with asymptomatic bradycardia have a very low rate of pacemaker implantation, annualized to <1% per year. Their higher rate of pacemaker implantation compared to outpatients without bradycardia shows a latency period of approximately 4 years. It has no adverse impact on all-cause mortality and may even be protective.