Predictive value of ambulatory heart rate in the Japanese general population: The Ohasama study

BACKGROUND: Resting heart rate can predict cardiovascular disease mortality or all-cause mortality. Because of the effect of the alert reaction, heart rates measured out-of-office should have better predictive power than those obtained at clinics. However, only a few studies have described the relationship between heart rate measured by ambulatory blood pressure monitoring devices and cardiovascular disease prediction. METHODS: We studied 1444 individuals from the Japanese general population who did not have a history of cardiovascular diseases including arrhythmia. We used multiple adjusted Cox proportional hazards to calculate the mortality risk of daytime heart rate, night-time heart rate, and the day-night heart rate dip ratio [day-night heart rate dip ratio = (daytime heart rate - night-time heart rate)/daytime heart rate × 100]. RESULTS: After 12 years of follow-up, 101, 195, and 296 participants died due to cardiovascular diseases, noncardiovascular diseases, and all causes, respectively. As shown by others, neither daytime nor night-time heart rate predicted cardiovascular disease mortality, whereas both predicted noncardiovascular disease mortality. The day-night heart rate dip ratio was significantly related to all-cause mortality. When night-time heart rate and day-night heart rate dip ratio were simultaneously included into the same Cox model, only night-time heart rate significantly and independently predicted all-cause mortality (relative hazard per 10 bpm increase = 1.29, 95% confidence interval, 1.07-1.54). CONCLUSION: Night-time heart rate value seems to have the most important predictor of all-cause mortality among ambulatory heart rate parameters in this population.