Non–Q-Wave Versus Q-Wave Myocardial Infarction After Thrombolytic Therapy

Abstract

Background —Although the stratification of patients with myocardial infarction into ECG subsets based on the presence or absence of new Q waves has important clinical and prognostic utility, systematic evaluation of the impact of thrombolytic therapy on the subsequent development and prognosis of non–Q-wave infarction has been limited to date. Methods and Results —We examined 12-lead ECG, coronary anatomy, left ventricular function, and mortality among 2046 patients with ST-segment elevation infarction from the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries angiographic subset to gain further insight into the pathophysiology and prognosis of Q- versus non–Q-wave infarction in the thrombolytic era. Non–Q-wave infarction developed in 409 patients (20%) after thrombolytic therapy. Compared with Q-wave patients, non–Q-wave patients were more likely to present with lesser ST-segment elevation in a nonanterior location. The infarct-related artery in non–Q-wave patients was more likely to be nonanterior (67% versus 58%, P =.012) and distally located (33% versus 39%, P =.021). Early (90-minute, 77% versus 65%, P =.001) and complete (54% versus 44%, P <.001) infarct-related artery patency was greater among the non–Q-wave group. Non–Q-wave patients had better global (ejection fraction, 66% versus 57%; P <.0001) and regional left ventricular function (10 versus 24 abnormal chords, P =.0001). In-hospital, 30-day, 1-year, and 2-year (6.3% versus 10.1%, P =.02) mortality rates were lower among non–Q-wave patients. Conclusions —The excellent prognosis among the subgroup of patients who develop non–Q-wave infarction after thrombolysis is related to early, complete, and sustained infarct-related artery patency with resultant limitation of left ventricular infarction and dysfunction.