The use of beta-blockers in unstable angina: comparison with calcium channel blocking agents.

The pathophysiology of unstable angina comprises critical narrowing of large coronary vessels by advanced atherosclerotic plaques, thrombus formation, and vasospastic reactions. Therapeutic goals aim primarily at an increase of flow and include vasodilation, thrombolytic strategies, and antithrombotic procedures (anticoagulation, antiaggregation). In the complex system of myocardial blood flow regulation, under normal and ischemic conditions, coronary vasomotor tone plays an important role. Especially in patients prone to vasospastic reactions, coronary vessels can be constricted by blockade of beta 2-receptors, which can lead to undesirable effects. Controlled clinical trials have clearly demonstrated that calcium antagonistic drugs and organic nitrates are safe and beneficially effective in such patients. beta-Blockers are usually not necessary if nitrates are combined with a calcium channel blocker of the verapamil type.