Relationships Between Baseline Q Waves, Time From Symptom Onset, and Clinical Outcomes in ST-Segment–Elevation Myocardial Infarction Patients

Background— Using a comprehensive ST-segment–elevation myocardial infarction registry, we evaluated the relationships of baseline Q waves, time from symptom onset, and reperfusion strategy with in-hospital clinical outcomes. Methods and Results— Consecutive ST-segment–elevation myocardial infarction patients from a defined health region were classified by the presence of baseline Q waves and additionally into primary percutaneous coronary intervention, fibrinolysis, or no reperfusion. ECGs were collected at baseline, after reperfusion, and analyzed for the presence of Q waves using Selvester criteria. Among 2290 ST-segment–elevation myocardial infarction patients, 36.9% had Q waves on their baseline ECG. Patients with Q waves were older (median age, 59 versus 57), were more often male (82.0% versus 75.4%), had higher heart rate (80 versus 72), had higher Global Registry of Acute Coronary Events risk score (129 versus 127), and were with longer time to reperfusion (42 minutes longer). They had higher composite end points (16.3% versus 10.0%), consistent across times from symptom onset to presentation (15.4% versus 9.9% ≤3 hours; 18.5% versus 8.9% >3 to ≤6 hours; 15.9% versus 11.3% >6 hours; Q and no Q, respectively). Baseline Q waves, but not time to reperfusion, were associated with an increased odds of the in-hospital composite end point of death, congestive heart failure, cardiogenic shock, and reinfarction (adjusted odds ratio, 1.65; 95% confidence interval, 1.18–2.30;P =0.003). Type of reperfusion did not modify the association of baseline Q waves and in-hospital outcomes (P interaction=0.918).Conclusions— The presence of baseline Q waves, rather than time to treatment, was significantly associated with adverse in-hospital events in real-world patients, regardless of reperfusion strategy used.