Comparison of Effects of Antihypertensive Drugs on Heart Rate Changes From Baseline by Baseline Group and Over Time

Baseline heart rate is becoming recognized as a predictor of cardiovascular risk. Various antihypertensive drugs have differing effects on heart rate. A randomized controlled clinical trial of 1292 ambulatory men with stage 1 or 2 hypertension was conducted in 15 Veterans Affairs medical centers. Patients were treated with hydrochlorothiazide, atenolol, captopril, clonidine, diltiazem, prazosin, or placebo for up to 2 years. Heart rates were measured at baseline, the end of titration, 1 year, and 2 years. Data were also stratified by baseline heart rate. A subset of patients had heart rate also determined by electrocardiogram. All drugs except prazosin reduced heart rate from baseline; additional small decreases were obtained over time with hydrochlorothiazide and placebo. The decrease initially achieved with clonidine was attenuated over time. The overall reduction in heart rate was greatest for atenolol (-12.2 beats/min) and least for prazosin (+3.8 beats/min). Only atenolol effected a further reduction of heart rate for patients whose baseline rate was < or =65 beats/min. All drugs reduced heart rate when the baseline was > or =85 beats/min. Data derived by electrocardiogram yielded similar results. The drugs used in this study differ in their ability to reduce heart rate, sustain that reduction over time, and to change heart rate in groups with high or low rates at baseline. The importance of these comparative changes as independent cardiac risk factor variables remains to be determined.