Background: The TIMI risk score for unstable angina and non-ST elevation myocardial infarction is an effective tool for predicting the risk of death and ischemic events among patients with non-ST elevation acute coronary syndromes, as well as for identifying those who are likely to benefit most from low-molecular-weight heparin and glycoprotein IIb/IIIa inhibition.
Methods: To explore the pathobiologic basis for this interaction, we evaluated the relationship between the risk score, assessed at presentation, and angiographic findings among patients with non-ST elevation acute coronary syndromes. Angiographic data regarding thrombus, epicardial flow, and lesion severity were available for 1491 patients from the angiographic substudy of PRISM-PLUS.
Results: Patients with risk scores of 5 to 7 (N = 435) were more likely to have a severe culprit stenosis (81% vs 58%, P < .001) and multivessel disease (80% vs 43%, P < .001) compared to those with scores of 0 to 2 (N = 220). The probability of left main disease (P = .01), visible thrombus, and impaired flow in the culprit lesion also increased progressively with rising risk scores (P < .001). Of the risk indicators that comprise the score, history of coronary disease, advanced age, and ST changes showed the strongest association with severe epicardial disease. Positive biomarkers of necrosis, ST changes, and prior aspirin use emerged as stronger correlates of visible thrombus and/or impaired culprit artery flow.
Conclusions: The TIMI risk score identifies patients who are more likely to have intracoronary thrombus, impaired flow, and increased burden of coronary atherosclerosis. These findings likely explain in part the particular benefit of potent antithrombin and antiplatelet agents among patients with higher risk scores.