Prognostic significance of baseline heart rate and its interaction with beta-blocker use in resistant hypertension: a cohort study.

BACKGROUND The prognostic significance of heart rate (HR) and its relationship with beta-blocker use are controversial and have never been evaluated in resistant hypertension. METHODS In a prospective study, 528 patients with resistant hypertension had HR measured on clinical examination, electrocardiography (ECG), and during ambulatory blood pressure monitoring. Primary endpoints were a composite of fatal and nonfatal cardiovascular events, all-cause and cardiovascular mortality. Multivariable Cox regression was used to assess the associations between slow HR (< 60 bpm or < 55 bpm for nighttime HR) and fast HR (> 75 bpm or > 70 bpm for nighttime HR) and the occurrence of endpoints in relation to the reference middle HR (60-75 bpm) subgroup. RESULTS After a median follow-up of 4.8 years, 62 patients died, 44 from cardiovascular causes; and 94 cardiovascular events occurred. Fast and slow HRs were mainly predictors of mortality, and ambulatory HRs were more significant risk markers than clinic or ECG HR. A slow 24-hour HR was a predictor of the composite endpoint (hazard ratio, 2.0; 95% confidence interval [CI], 1.2-3.4), whereas both slow and fast ambulatory HRs were predictors of cardiovascular mortality (hazard ratio, 2.3; 95% CI, 1.1-5.1). Four hundred and seventeen patients (79%) were using beta-blockers and this affected the HR prognostic value. A fast HR was a more significant risk marker in patients using beta-blockers, whereas a slow HR was a predictor mainly in those not using beta-blockers. CONCLUSIONS There is an overall U-shaped relationship between HRs, particularly when measured during ambulatory monitoring, and prognosis in resistant hypertension. A fast HR is a significant predictor in patients using beta-blockers, while a slow heart rate is a more important predictor in those not using beta-blockers.