The Medical Research Council Hypertension Trial: the smoking patient

Tobacco smoking is a powerful risk predictor for coronary disease. In the recent Medical Research Council (MRC) Hypertension Trial, which this article discusses, it also proved to be an important predictor of stroke. The MRC trial had two active treatment groups, one of which received bendrofluazide and the other propranolol. The main positive result of the trial was a 45% reduction in stroke events in the actively treated groups. Propranolol appeared to be much less effective than bendrofluazide in the prevention of stroke in smokers, although both active drugs were equally effective in nonsmokers. Possible explanations for this lack of efficacy in smokers are discussed. Coronary events were not reduced by treatment, although there was a trend toward their reduction in nonsmoking men treated with propranolol. The lack of effect of propranolol in reducing coronary morbidity and mortality rates was a surprise in view of the positive results from trials with both short-term and long-term treatment with beta-adrenergic blockade after myocardial infarction.