Interactions between antihypertensive agents, serum lipids and cigarette smoking in high risk hypertensive patients

Treatment of hypertension aims at preventing strokes and coronary events. Although diuretics and beta-blockers lowered blood pressure effectively and allowed prevention of strokes in large-scale trials, they did not reduce the incidence of myocardial infarction or coronary death. The failure of diuretics and beta-blockers to afford cardiac protection may be due in part to the unfavourable effects of these agents on associated risk factors like hyperlipidaemia and smoking. Hyperlipidaemia is more prevalent in hypertensive patients than in matched normotensive controls, and the combination of hyperlipidaemia and smoking is more frequent than can be expected to occur by chance. Diuretics and beta-blockers affect lipid metabolism negatively. Unlike these agents, alpha-blockers do not alter serum lipids and might reduce triglyceride and cholesterol levels. Several trials have shown that the outcome of treatment with beta-blockers was less favourable in smokers than in non-smokers in terms of blood pressure control and prevention of coronary events. A possible explanation is provided by acute experiments in which beta-blockade enhanced the systemic and coronary vasoconstriction elicited by smoking, while alpha-blockade had the opposite effect. Although there is reason to believe that alpha-blockers may be preferable to diuretics and beta-blockers for the treatment of high risk hypertensive patients who smoke and/or exhibit high levels of serum lipids, there is a need for larger and longer trials to test their ability to reduce cardiovascular risk.