Thrombolytics and Invasive vs Conservative Strategies in Unstable Angina

Acute coronary syndromes represent a clinical spectrum that extends all the way from unstable angina presenting with a transient episode of chest pain, to non-ST-elevation myocardial infarction (MI) with more prolonged chest pain and biochemical evidence of MI, to ST-elevation MI with more extensive myocardial damage and formation of Q waves on the surface electrocardiogram (ECG), and finally to sudden cardiac death. Pathophysiologic correlations include minor plaque ulceration and transient thrombus formation in unstable angina, more extensive thrombosis in non-Q wave MI, and complete occlusion in ST-elevation MI and sudden death. Despite initially promising small studies, a large randomized trial showed that thrombolytic therapy is not beneficial and may even be harmful in unstable angina and non-ST-elevation MI. Several trials have compared conservative vs early invasive strategies in unstable angina and non-ST-elevation MI. Results of these trials were conflicting, and most antedated the use of platelet glycoprotein (GP) IIb/IIIa receptor inhibitors and coronary stenting. Risk stratification models, based on simple clinical and laboratory parameters, potentially might allow identification of high risk patients who will benefit the most from an early invasive approach and those with lower risk, in which early conservative management may be more appropriate.