The Association of Resting Heart Rate and Incident Hypertension: The Henry Ford Hospital Exercise Testing (FIT) Project

BACKGROUND Given that sympathetic tone is associated with hypertension, we sought to determine whether resting heart rate (RHR), as a surrogate for cardiac autonomic function, was associated with incident hypertension. METHODS We analyzed 21,873 individuals without a history of hypertension who underwent a clinically indicated exercise stress test. Baseline RHR was assessed prior to testing and was categorized as < 70, 70-85, and > 85 beats-per-minute (bpm). Incident hypertension was defined by subsequent diagnosis codes for new-onset hypertension from three or more encounters. We tested for effect modification by age (< 60 vs. >= 60 years), sex, race, and history of coronary heart disease (CHD). RESULTS Mean (+/- SD) age was 49 (+/- 12) years, 55% were men and 21% were Black. Compared to the lowest RHR (<70 bpm) category, patients in the highest category (>85 bpm) were younger, more likely to be female, heavier, diabetic, and achieve lower metabolic equivalents (METS). Over a median of 4 years follow-up, there were 8,179 cases of incident hypertension. Compared to RHR <70 bpm, persons with RHR >85 bpm had increased risk of hypertension after adjustment for CHD risk factors, baseline blood pressure (BP), and METS (hazard ratio = 1.15 (95% confidence interval 1.08-1.23)). Age was an effect modifier (interaction P = 0.02), whereas sex, race, and CHD were not. In age-stratified analyses the relationship remained significant only in those younger than 60 years. CONCLUSION Elevated RHR is an independent risk factor for incident hypertension, particularly in younger persons. Whether lifestyle modification or other strategies to reduce RHR can prevent incident hypertension in high-risk individuals warrants further study.