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(Hypertension. 2005;46:1053.)
© 2005 American Heart Association, Inc.

Part 2 Original Articles

Effects of Time of Day of Treatment on Ambulatory Blood Pressure Pattern of Patients With Resistant Hypertension

Ramón C. Hermida; Diana E. Ayala; Carlos Calvo; José E. López; Artemio Mojón; María J. Fontao; Rita Soler; José R. Fernández

From the Bioengineering and Chronobiology Laboratories (R.C.H., D.E.A., A.M., M.J.F., R.S., J.R.F.), University of Vigo, Campus Universitario, Spain; and Hypertension and Vascular Risk Unit (C.C., J.E.L.), Hospital Clínico Universitario, Santiago de Compostela, Spain.

Correspondence to Prof Ramón C. Hermida, PhD, Director, Bioengineering and Chronobiology Laboratories, E.T.S.I. Telecomunicación Campus Universitario Vigo (Pontevedra) 36200, Spain. E-mail rhermida{at}tsc.uvigo.es

Patients with resistant hypertension present high prevalence of a non-dipper blood pressure pattern. Recent results indicate that non-dipping is related partly to the absence of 24-hour therapeutic coverage in patients treated with single morning doses. Accordingly, we investigated the impact of treatment time on the blood pressure pattern in 700 patients with resistant hypertension on the basis of clinic measurements who were studied by 48-hour ambulatory monitoring. Among them, 299 patients received all their medication on awakening, and 401 were taking 1 antihypertensive drug at bedtime. The percentage of patients with controlled ambulatory blood pressure was double in patients taking 1 drug at bedtime (P=0.008). Among the 578 patients with true resistant hypertension, subjects receiving 1 drug at bedtime showed a significant reduction in the 24-hour mean of systolic and diastolic blood pressure (3.1 and 1.6 mm Hg, respectively; P<0.011). This reduction was much more prominent during nighttime (5.1 and 3.0 mm Hg; P<0.001). Accordingly, the diurnal/nocturnal blood pressure ratio was significantly increased by 2.7 and the prevalence on non-dipping reduced (56.9 versus 81.9%; P<0.001) in patients taking 1 drug at bedtime. Compared with patients receiving all drugs on awakening, subjects with 1 drug at bedtime also showed significant reductions in the average values of glucose, cholesterol, fibrinogen, and urinary albumin excretion (P<0.011). In patients with resistant hypertension, pharmacological therapy should take into account when to treat with respect to the rest–activity cycle of each patient to improve control and to avoid the non-dipper pattern associated to higher cardiovascular risk.

Key Words: blood pressure monitoring, ambulatory • circadian rhythm