Beta Blockers and Hypertension: Treatment Method
Beta blockers is a class of medication used for managing hypertension, cardiac arrhythmias, and for secondary prevention for people already had heart attacks.There are several types of beta blockers, including atenolol, propranolol, metoprolol, labetalol, bisoprolol, acebutolol, and carvedilol.
Khan and McAlister (2006) surveyed data from 21 hypertension trials involving 145,811 participants. They showed that beta blockers reduced major cardiovascular outcomes by 14% (risk ratio: 0.86) in younger patients and 11% (risk ratio: 0.89) in older patients. Beta blocker therapy also improves the survival rate among heart attack patients by almost 100%. For instance, in the Carvedilol Post-Infarct Survival Control in LV Dysfunction (CAPRICORN) trial, about 2000 patients with a proven acute myocardial infarction and a left-ventricular ejection fraction of less than 40% were randomly assigned 6·25 mg carvedilol or placebo and followed for 2.5 years. The study showed that cardiovascular mortality, non-fatal myocardial infarctions, and all-cause mortality or non-fatal myocardial infarction were lower in the carvedilol group than in the placebo group. More specifically, all-cause mortality was reduced by 23% in the carvedilol group.
However, the question is whether beta blockers are effective as other medications for hypertension. Several trials have been conducted to address this question.
In the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT), patients were randomized to amlodipine with addition of perindopril as required (amlodipine-based) or atenolol with addition of thiazide as required (atenolol-based). Therapy was titrated to achieve a target blood pressure of less than 130/80 mmHg. The result of the trial demonstrated that amlodipine (a calcium channel blocker) is more effective than atenolol (a beta blocker) in term of preventing cardiovascular events. The risk ratio between the amlodipine and atenolol arm for fatal and nonfatal strokes were 0.75 (P = 0.017), peripheral arterial disease by 0.52(P = 0.004) and noncoronary revascularization procedures by 0.43 (P < 0.001).
Meta-analysis of trials similar to ASCOT indicate that comparing with other antihypertensive agents, beta blockers show better efficiency in younger patients (risk ratio: 0.97) but not older patients (risk ratio: 1.08) (see Khan and McAlister, 2006).
Based on new evidences on efficacy of beta blockers, Lindholm et al suggested that beta blockers should not remain first choice in the treatment of primary hypertension and should not be used as reference drugs in future randomised controlled trials of hypertension.
References
Re-examining the efficacy of {beta}-blockers for the treatment of hypertension: a meta-analysis Khan and McAlister, 2006
