Abstract 12241: Exploring the Interaction Between Nighttime Heart Rate and Heart Rate Variability on Future Cardiovascular Event

Abstract

Introduction: High nighttime heart rate or heart rate variability assessed by ambulatory blood pressure monitoring (ABPM) has been reported to be risk for cardiovascular events. However, it is not clear whether these indices provide synergic risk for cardiovascular events. Hypothesis: The aim of this study is to explore the interaction between nighttime heart rate and heart rate variability on future cardiovascular event. Methods: We studied 1418 patients (average age 64.6±11.6 years, male 47.9%) from J-HOP study who were performed ABPM. We divided average nighttime heart rate (NHR) and nighttime heart rate variability (NHRV) defined as standard deviation of nighttime heart rate into decile groups, and defined the top decile group (NHR 70bpm, NHRV 9.7bpm) as abnormal group, respectively. The average follow-up period was 5.0 years and the incidence of cardiovascular event was 56 events. Results: Kaplan-Meier curve showed that the incidence of cardiovascular event with abnormal NHR and NHRV was higher than those without (Figure A and B). When we divided the patients into 4 groups according to those with or without abnormal NHR and with or without abnormal NHRV, the incidence of cardiovascular event for the group with both abnormal NHR and NHRV was the highest among 4 groups (Figure C). After adjustment for age, sex, body mass index, smoking, alcohol, past history of cardiovascular disease, diabetes, dyslipidemia and 24hr systolic blood pressure, abnormal NHR and NHRV, the presence of abnormal HHR and NHRV has a synergic risk for cardiovascular event (Odds ratio, 7.27; 95% confidence interval, 1.53 to 34.60, P<0.013). Conclusions: The presence of nighttime higher heart rate and heart rate variability obtained every 30 minutes by ABPM has a synergic risk for cardiovascular event.