Thrombolysis and Q Wave Versus Non-Q Wave First Acute Myocardial Infarction: GUSTO-I Substudy

Objectives. We assessed the outcomes of patients with first myocardial infarction with ST segment elevation, with and without the development of abnormal Q waves after thrombolysis. Background. Prethrombolytic er studies report conflicting short- versus long-term mortality in the overall non-Q wave population, probably related to its heterogeneity. Methods. Patients with no electrocardiographic (ECG) confounding factors or evidence of previous infarction were included. Q wave infarction was defined as Q wave duration ≥30 ms in lead aVF; R wave ≥40 ms in lead V1; any Q wave or R wave ≤10 ms and ≤0.1 mV in lead V2; or Q wave ≥40 ms in at least two of the following leads: I, aVL, V4, V5 or V6. In-hospital clinical events and mortality at 30 days and 1 year were assessed. Results. No Q waves developed in 4,601 (21.3%) of the 21,570 patients. This group comprised more women and had lower Killip class, lower weight and less anterior baseline ST elevation. The non-Q wave group had less in-hospital cardiogenic shock (2.1% vs. 3.3%, p < 0.0001), less heart failure (8.5% vs. 13.9%, p < 0.0001) and trend toward less stroke (0.7% vs. 1.0%, p = 0.07) but an increased use of angioplasty (28% vs. 24%, p = 0.0001). The unadjusted mortality rate in the non-Q wave group was lower at 30 days (0.9% vs. 1.8%, p = 0.0001) and 1 year (2.7% vs. 4.2%, p = 0.0001), as was the adjusted 30-day mortality rate (4.8% vs. 5.3%, p < 0.0001). Conclusions. Patients with no ECG confounding factors or evidence of previous infarction who do not develop Q waves after thrombolysis have better 30-day and 1-year prognosis than patients with Q wave infarction.