The Hypertension‐CHD Dilemma

The Hypertension-CHD DilemmaIn high-cholesterol countries such as the USA and most Western European countries, hypertension, through numerous epidemiological studies, has been established as a definite and important risk factor for the development of coronary heart disease (CHD).This is in contrast to the epidemiological situation in certain Eastern countries.In these lowcholesterol countries the prevalence of CHD is extremely low despite a rather high prevalence of hypertension.It is believed that hypertension needs the metabolic basis of a certain blood lipid level to become an atherogenic factor of clinical importance.In most countries in the Western World this metabolic basis is endemic and hypertension is recognized as a definite risk factor for CHD.Nevertheless, randomized, controlled hypertension drug trials with placebo-treated or untreated control groups have failed to show a definite preventive effect on CHD.Thus, the Australian trial (l), the best designed hypertension study, with both placebo-treated controls and adequate numbers, came out with the same MI incidence figures in the drugtreated and the placebo-treated group (33 in each group after 4 years).The test drugs in this study were a thiazide (first step), adding a p-blocker or methyldopa (second step), and hydralazine or clonidine (third step).In the smaller Oslo Study of mild hypertension (2) the control group was untreated.The men in this study, aged 40-49, were followed for 5 years.The 5-year total mortality was the same in both groups, while there were 20 fatal and non-fatal coronary events in the drug-treated group and 13 in the control group (NS).After 10 years, total mortality was still the same in both groups (21 in the treated vs. 20 in the untreated group), while the CHD mortality figures were definitely to the disadvantage of the drug-treated group (14 vs. 3, p<O.OI) (3).About 95% of the drug-treated men received a thiazide, alone or in combination with other drugs, mainly propranolol or methyldopa.In the extensive American Multiple Risk Factor Intervention Trial (MRFIT) of 12866 CHD high risk men, aged 35-57 (4), about 8000 men in the special intervention group (SI) and in the control group (UC) were regarded as hypertensives.In the SI group these men were treated with a thiazide or chlorthalidone as the first drug.After 7 years both total and CHD mortality were the same in both groups.However, in a subgroup of about 2400 hypertensive men with minor resting ECG abnormalities at start, a 65% excess CHD mortality occurred in the SI group (29.2 vs. 17.7 per 1OOO).Using the MRFIT ECG criteria, the same trend with excess CHD incidence in the experimental groups was also found in the Hypertension Detection Follow-up Program and in the Oslo Study.These results are in sharp contrast to the achievement in 2087 non-hypertensive smokers with a high initial cholesterol level, in whom CHD mortality decreased by 49% after diet and antismoking advice.This subgroup of MRFIT is similar to the men in the Oslo Study diet-smoking trial (5) in which a reduction in CHD incidence of the same order was achieved in the intervention group as compared with the control group. 10-858702