PO-03-074 INITIAL HEART RATE SCORE IS PREDICTOR FOR OCCURRENCE OF NEW ATRIAL FIBRILLATION INDEPENDENT OF WELL-KNOWN RISK FACTORS AND RELATES TO RIGHT ATRIAL PACING RATE IN PACEMAKER PATIENTS

Abstract

Heart Rate Score (HRSc), the percent of right atrial (RA) beats in the largest paced or sensed 10-bpm histogram bin, predicts survival in ICD and CRT-D patients without atrial fibrillation (AF). For pacemaker (PM) patients, although age, gender and RA and right ventricular pacing percent (% RA and RV pacing) have been related to AF, the relationship of HRSc to subsequent AF is unknown. To evaluate the relationship between initial post implantation HRSc and incidence of newly developed AF, and well-known predictors for AF in PM patients. Patients with dual-chamber, atrial tracking PMs, implanted 2013-2017, who had ALTITIUDE remote monitoring data available, were included. HRSc was determined from histogram data during the first 3 months post-implant. Only patients with ≥600,000 beats of histogram data collected at baseline were included. Patients with single-chamber or biventricular PMs were excluded. Patients were excluded if they had AF, defined as atrial high rate episodes >5 minutes or >1% of RA beats >170 bpm during the initial 3-months post-implant. AF after the baseline period was evaluated by the definition: >1% of atrial beats >170 bpm. Sinus node disease (SND) was defined as needed for RA pacing ≥ 40% and atrio-ventricular block (AVB) as needed for right ventricular pacing ≥ 20% during the baseline period. Of the total population (N=34,543), 15,252 patients had device-determined SND and 16,190 patients had AVB. Utilizing multivariable analysis, the initial HRSc (HR: 1.07, 95% CI: 1.05-1.09; P<0.0001) independently predicted subsequent AF after adjusting for age, gender, % RV pacing and rate-response programming. Patients with initial HRSc≥70% were older, and had higher % RA pacing, lower % RV pacing and were more likely programmed with rate-response vs subjects with initial HRSc<70%. There was a direct, and significant, increase in new-onset AF with each 20% increment in HRSc and/or % RA pacing (both P<0.001, Figure) during median of 2.8 (1.0-4.0) years follow-up. The %RA pacing and initial HRSc were strongly correlated (Pearson correlation coefficient=0.9). % RV pacing did not predict AF. Both SND patients and AVB patients with initial HRSc≥70% had a significantly increased risk of AF (log-rank P <0.001) compared to patients with HRSc<70%. Initial HRSc, strongly related to percent RA pacing, predicts subsequent AF independent of well-known risk factors in both device-determined SND and AVB.