Thrombolysis and Q wave versus non-Q wave first acute myocardial infarction: a GUSTO-I substudy. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Arteries Investigators.

OBJECTIVES: We assessed the outcomes of patients with a first myocardial infarction with ST segment elevation, with and without the development of abnormal Q waves after thrombolysis.

BACKGROUND: Prethrombolytic era 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 a Q wave duration > or = 30 ms in lead aVF; R wave > or = 40 ms in lead V1; any Q wave or R wave < or = 10 ms and < or = 0.1 mV in lead V2; or Q wave > or = 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 a 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 a 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 a better 30-day and 1-year prognosis than patients with a Q wave infarction.