THROMBOLYTIC THERAPY FOR UNSTABLE ANGINA

Thrombolytic therapy for unstable angina has not gained acceptance as a primary treatment for unstable angina (UA) despite the evidence show ing a reduction in mortality when these agents are given for myocardia l infarction. The purpose of this review is to examine the clinical va lue of thrombolytic therapy for UA. The multiple lines of evidence sup porting intracoronary thrombus formation as a key mechanism in the pat hogenesis of UA are reviewed. Studies examining the effect of thrombol ytic therapy on angiographic endpoints have shown little effect on the extent of luminal narrowing, but do reveal a decrease in angiographic ally detected thrombus. Twelve randomized, controlled trials of thromb olytic agents in 611 UA patients with predefined clinical endpoints ha ve been published. These trials varied widely in design and adjunctive therapy both in treated and control groups. Review of these trials sh ows a tendency to fewer clinical events such as death, infarction, and need for revascularization in treated patients, with a corresponding increase in bleeding complications. Clinical efficacy of thrombolytic therapy cannot be excluded by the available data, perhaps in part beca use of insufficient numbers of patients treated. Determination of the net clinical value of thrombolytic therapy must await larger and more definitive trials.