Primary prevention in patients with hypertension: comments on the clinical implications of the MAPHY Study. Metoprolol Atherosclerosis Prevention in Hypertensives Study.

The MAPHY Study was conducted to investigate whether metoprolol, a relatively beta 1-selective beta-blocker, given as initial antihypertensive treatment, would lower cardiovascular complications of high blood pressure to a greater extent than do thiazide diuretics as initial treatment at similar blood pressure control. In a controlled, randomized, stratified primary prevention study (n = 3234; 16,180 patient-years) in white men (40 to 64 years old) with mild to moderate uncomplicated hypertension, a treatment schedule starting antihypertensive treatment with metoprolol was compared with treatment starting with a thiazide diuretic. The two treatment groups were well matched in blood pressure and other major clinical characteristics at randomization, as well as at the last follow-up during treatment. Total mortality was significantly lower in patients randomized to metoprolol. At the median follow-up time (4.2 years) 28 deaths occurred in the metoprolol group and 54 in the diuretic group--a difference of 48% in total mortality (95% confidence limit, ranging from 68% to 17%), mainly because of a highly significant reduction in coronary heart disease at this point in time. The benefit demonstrated with metoprolol seems to have important implications for clinical practice and public health policy, since hypertension and coronary heart disease are major health problems worldwide.