Assessment of "optimal" beta blockade in treating patients with angina pectoris

Assessment of optimal beta blockade in treating patients with angina pectoris remains a challenge. Reduction in resting heart rate is a poor guide to therapy; the dose response curves are flat and drugs with intrinsic sympathomimetic activity may not lower resting heart rates despite their efficacy. Log plasma concentrations of beta blockers correlate with reduction in exercise tachycardia but not with improvement in exercise tolerance of reduction in myocardial ischaemia. Although useful, reduction in frequency of anginal attacks and nitroglycerin consumption during therapy is a poor guide in assessing optimal beta blockade. The best way to assess optimal therapy is to demonstrate maximum increase in exercise performance in association with reduction in myocardial ischaemia and adequate suppression of exercise-induced increase in heart rate and blood pressure. This requires repeated exercise testing at multiple work loads after various doses of the drug until there is no further increase in exercise duration or reduction in heart rate. When given in optimal and equipotent doses all beta blockers are equally effective antianginal agents and can be prescribed twice daily.