Initial Heart Rate Score Predicts New Onset Atrial Fibrillation in Pacemaker Patients

Background Heart Rate Score (HRSc), the percent of all atrial paced and sensed event in the largest 10 bpm rate histogram bin of a pacemaker, predicts survival in patients with cardiac devices. No correlation between HRSc and development of atrial fibrillation (AF) has been reported. Objective To evaluate the relationship between pacemaker post-implantation HRSc and newly-developed AF incidence. Methods Patients with dual-chamber pacemakers, implanted 2013-2017, with ALTITIUDE remote monitoring data with ≥600,000 beats of histogram data collected at baseline were included (N=34,543). HRSc was determined from the post-implantation histogram data during the initial 3 months. Patients were excluded if they had AF, defined as atrial high-rate episodes >5 minutes or >1% of right atrial beats >170 bpm during the initial 3-months post-implantation. New AF, after the baseline period, was defined by each of the following: >1%, >10% or >25% of atrial beats >170 bpm or Atrial Tachycardia Response (ATR) events >24 hr. Results Patients were followed a median of 2.8 (1.0-4.0) years. Patients with initial HRSc≥70% were older, had higher %RA pacing, had lower %RV pacing and were more likely programmed with rate-response vs subjects with HRSc<70%. The incidence of AF increased in proportion to HRSc (Log-Rank P-value <0.001); results were insensitive to AF definition. Initial HRSc (HR:1.07, 95% CI:1.05-1.09; P<0.0001) independently predicted AF after adjusting for age, gender, % RV pacing and rate-response programming. The %RA pacing and initial HRSc correlated. Conclusion HRSc predicts subsequent AF independent of well-known risk factors in pacemaker patients.