Characterization of antihypertensive therapy by whole-day blood pressure monitoring.

Whole-day ambulatory monitoring is used for diagnosing hypertension and for judging response to treatment. We evaluated both of these properties in an antihypertensive trial with the calcium channel blocker diltiazem hydrochloride. Measured by a conventional sphygmomanometer, systolic and diastolic blood pressures fell significantly in patients who received diltiazem, whereas no consistent changes occurred in those who received placebo. Administration of the drug also decreased systolic and diastolic blood pressures evenly throughout the day, as determined by automated monitoring. The 15 diltiazem-treated patients were subdivided into those whose clinically diagnosed hypertension was confirmed by pretreatment blood pressure monitoring (24-hour average diastolic blood pressure, greater than or equal to 90 mm Hg; n = 9) and those whose 24-hour blood pressures failed to meet this criterion (n = 6). Diltiazem therapy decreased average whole-day blood pressures by 18/13 mm Hg in the hypertensives but by only 0/1 mm Hg in the others. Thus, whole-day blood pressure monitoring strengthens antihypertensive trials by documenting efficacy and duration of treatment. In addition, it enhances the diagnosis of hypertension, thereby identifying those patients in whom treatment seems justified.