Clinical relevance of intrinsic sympathomimetic activity of beta blockers.

beta-Blockers are effective in the symptomatic relief of angina pectoris by decreasing myocardial oxygen demand during effort and emotional stress. Agents with ISA such as pindolol produce effective beta-blockade during effort or emotional stress while conferring significant protection from myocardial depression and bradycardia at rest. In addition, agents with ISA have been shown to depress respiratory function to a lesser extent and to induce fewer peripheral vascular side effects than compounds devoid of this property.