Relation of reduction in pressure to first myocardial infarction in patients receiving treatment for severe hypertension.

In order to examine the widely held belief that the aim of antihypertensive therapy should be to restore "normality," the relative risk of myocardial infarction and sudden death was related to the extent of pressure reduction in a survey of 169 patients with uncomplicated essential hypertension followed-up under treatment over a mean period of 6.25 years. Apart from the effects of the hypotensive agents, there were no statistically significant differences in coronary heart-disease (C.H.D.) risk factors between the patients who had and those who did not have an infarction. Overall average values for final diastolic pressure (F.D.P.), as last recorded before the end of the study, were almost the same in the two groups. But the relative risk of myocardial infarction in the patients with F.D.P. reduced to less than 90 mm Hg was more than five times that in the patients with F.D.P. 100--109 mm Hg (P less than 0.01), while in those who had developed infarcts with F.D.P.S of less then or equal to 90 mmHg the pressure falls were all markedly greater than in unaffected controls matched for C.H.D. risk factors that included form of treatment, age, sex, and established pre-treatment diastolic pressure (E.D.P.). Thus it would seem that, in severe middle-aged hypertensives, attempts at "normalisation" of high blood-pressure may precipitate as many infarctions as it prevents. Other cardiovascular complications did not exceed the incidence expected during treatment. The findings suggest that the blood-pressure in such patients should seldom be reduced by more than 22% or to diastolic levels less than 104--110 mm Hg.