ABSTRACT
Beta-blockers have long being used as first-line therapy for hypertension as their use had resulted in a reduction in cardiovascular morbidity and mortality in controlled clinical trials. A recent meta-analysis comparing beta-blockers to all other anti-hypertensive drugs taken together has found that stroke reduction was sub-optimal. Specifically, atenolol was associated with a 26% higher risk of stroke compared with other drugs. Several reasons may explain the less favourable outcomes with beta-blocker therapy. These include some adverse metabolic abnormalities such as dyslipidaemia and new-onset diabetes, and less effective reduction of central aortic compared with brachial blood pressure. Newer beta-blockers such as carvedilol or nebivolol are better tolerated. These beta-blockers have a vasodilating effect, which may beneficially affect systolic blood pressure in the aorta. Their long-term cardiovascular outcome in hypertension is still not known. Further studies would be required to show that stroke is adequately reduced by these newer beta-blockers. In conclusion, beta-blockers should not be the first drugs of choice in the management of uncomplicated hypertension. They may be used in addition to other anti-hypertensive agents to achieve blood pressure goals. However, in patients with angina pectoris, a previous myocardial infarction, heart failure and certain dysrhythmias, beta-blockers still play an important role.
Beta-blockers have been widely prescribed to treat hypertension over the years.1 While the benefits of these agents in reducing cardiovascular events in people with pre-existing heart disease are clear,2 their clinical benefits in individuals with uncomplicated hypertension are less well-defined. Questions have been raised about beta-blockers as first-line treatment options in hypertension.3 The precise mechanism(s) of beta-blockers in lowering blood pressure is uncertain, although a decreased sympathetic tone and renin production are thought to play a role.4 The 2 Medical Research Council (MRC) trials completed in the 1970s5 and 1980s6 and 2 Swedish studies, the HAPPHY7 and the MAPHY Studies,8 are the earlier studies which provided supportive evidence for the use of beta-blockers for initial hypertension therapy. The 1993 JNC V guidelines suggested diuretics and beta-blockers as preferred initial agents as their use had resulted in a reduction in cardiovascular morbidity and mortality in controlled clinical trials.9 However, in most of these trials, the improved cardio-vascular outcomes had been mainly achieved by combining a beta-blocker and a diuretic.3,10
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