Does 24-hour ST-segment resolution postfibrinolysis add prognostic value to a Q wave? An ASSENT 2 electrocardiographic substudy

Background Both ST resolution and Q-wave development postfibrinolysis provide important prognostic insights in patients with acute myocardial infarction (MI). However, the relative contributions of these 2 factors to risk assessment have not been examined prospectively. Methods and results ST resolution and Q development were evaluated 24 to 36 hours (24–36h) postfibrinolysis in ASSENT-2: 13,100 out of 16,949 patients who had both baseline and 24–36h electrocardiograms free of confounders (left bundle branch block, ventricular rhythm, reinfarction before 24–36h electrocardiograms) were included in this analysis. Q-wave MI evolved in 10,466 patients (79.9%) and 2634 patients (20.1%) had non-Q–wave MI at 24–36h postfibrinolysis. Mortality rates at 1-year were 7.0% for patients with Q-wave MI and 5.8% for non-Q–wave MI patients, respectively (P = .046). Patients with Q-wave MI versus those without were less likely to have complete ST-segment resolution (49.1% vs 59.1%) and more likely to have partial (37.1% vs 27.8%) or no resolution (13.8% vs 13.1%) at 24 to 36 hours postfibrinolysis (P < .001). Mortality rates at 1 year for Q-wave MI with complete, partial, and no resolution were 5.2%, 8.1%, and 10.1%, respectively (P < .001), and for non-Q–wave MI with complete, partial, and no resolution were 4.5%, 7.6%, and 8.0% (P = .003). Conclusion These results demonstrate the additional prognostic significance of ST-segment resolution to Q-wave development at 24 to 36 hours after fibrinolysis.