Reproducibility of heart rate measured in the clinic and with 24-hour intermittent recorders

This study was undertaken to assess the reproducibility of office versus ambulatory heart rates in 839 hypertensive subjects participating in the Hypertension and Ambulatory Recording Venetia Study (HARVEST). A 24-hour heart rate was recorded twice; this procedure was repeated three months later. Reproducibility was better for ambulatory than for office measurement, and was greater for 24-hour than for daytime heart rate, and lowest for night-time heart rate. Reproducibility of office heart rate was impaired above 85 bpm, and was poorer in subjects with more severe office hypertension. A small but significant decrease in average daytime (-1 bpm, P < 0.0001) and virtually no change in night-time heart rate (-0.3 bpm, NS) were observed at repeat recording. Heart rate reproducibility indices were related to the extent of the heart rate and blood pressure white-coat effect, but did not vary according to age, gender, body mass index, day-night blood pressure difference, or alcohol or tobacco use. Results indicate that heart rate recorded over the 24 hours has a better reproducibility than office heart rate, and could thus be a better prognostic indicator than traditional measurement of resting heart rate in the hospital setting.