24-HOUR BLOOD-PRESSURE LOAD AS A SURROGATE END-POINT IN ASSESSING ANTIHYPERTENSIVE THERAPY

Aim: To examine the relationships among ambulatory blood pressure, blo od pressure load (proportion of elevated blood pressure values over 24 -h recording) and indices of hypertensive heart disease (left ventricu lar mass and left ventricular function) in untreated hypertensive pati ents. A secondary aim was to evaluate the usefulness of ambulatory blo od pressure load in assessing the long-term effects of antihypertensiv e drug therapy. Methods: Data were obtained from a study of 15 men wit h moderate to severe essential hypertension who had been treated with a placebo followed by 6-8 months of carvedilol monotherapy (25-75 mg/d ay). Blood pressure was evaluated by 24-h ambulatory monitoring. Resul ts: In studies of office or 'white-coat' hypertensives, ambulatory blo od pressure has proved a better predictor of target organ involvement than casual (clinic) pressure. Blood pressure loads of >50% for systol ic pressure and >40% for diastolic pressure are superior to clinic pre ssures, and also to the usual ambulatory monitoring parameters of mean 24-h, awake and sleeping blood pressure, in predicting left ventricul ar hypertrophy and abnormal diastolic performance. In the carvedilol s tudy, the mean awake systolic blood pressure load fell from 94 to 43% and the diastolic blood pressure load fell from 84 to 27% with carvedi lol treatment (P<0.001 in both cases). Of the patients treated with ca rvedilol monotherapy, 60% fell into the lower risk category (<50% syst olic blood pressure and <40% diastolic blood pressure load). Conclusio ns: These data support the use of blood pressure load in clinical stud ies of mild to moderate essential hypertension as a measure of the eff icacy of antihypertensive drugs.