Differences in betablocking drugs in cardiovascular therapy.

Clinically significant differences between various beta-adrenoceptor blocking drugs exist. Patients with ischaemic heart disease and exertional angina pectoris benefit from all types of beta-blockers. Drugs with intrinsic sympathomimetic action (ISA) given intravenously may be safer in some patients with acute myocardial infarction than those drugs without ISA. In cardiac patients at rest they may have a vasodilator action and cause less myocardial depression than beta-blockers without ISA. When, however, the cardiac sympathetic tone is high pindolol and other beta-blockers with ISA act as any other beta-blockers, producing haemodynamic impairment. Studies have shown that beta-blockers with ISA confer less benefit in secondary prevention after myocardial infarction and they are not suitable for the treatment of obstructive cardiomyopathy. Non-selective beta-blockers may be advantageous in hypokalaemic arrhythmias. Beta 1-blockers may be preferred for patients with bronchoconstriction, diabetes, peripheral vascular disease and, theoretically to some extent in theory also in patients with hypertension. The extent and nature of side effects may also influence the selection of the most suitable beta-blocker in cardiovascular therapy.