BACKGROUND

Presence of Q waves on the presenting electrocardiogram (ECG) in patients with ST-segment elevation myocardial infarction (STEMI) has been associated with worse prognosis; however, whether the prognostic value of Q waves is influenced by baseline characteristics and/or rapidity of revascularization based on the guideline-based metric of door-to-balloon time remains unknown.

HYPOTHESIS

We hypothesized that Q waves in the presenting ECG will be predictive of long term mortality regardless of time to reperfusion.

METHODS

The Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial enrolled 3602 patients with STEMI undergoing primary percutaneous coronary intervention. We stratified patients without prior history of myocardial infarction or coronary revascularization according to presence or absence of pathological Q waves on their presenting ECG. Associations between Q waves, death, and cardiovascular outcomes within 3 years were assessed using Cox proportional hazards regression.

RESULTS

Among 2723 patients with evaluable ECGs, 1084 (39.8%) had Q waves on their presenting ECG. Male sex and time from symptom onset to balloon inflation were independent predictors of presence of Q waves. Patients with Q waves had higher adjusted risks of all-cause death (adjusted hazard ratio: 1.45, 95% confidence interval: 1.02-2.05, P = 0.04) and cardiac death (adjusted hazard ratio: 1.72, 95% confidence interval: 1.08-2.72, P = 0.02). The association between Q waves and cardiac death was consistent regardless of sex, diabetes status, target vessel, or door-to-balloon time (P > 0.4 for all).

CONCLUSIONS

Presence of Q waves on the presenting ECG in patients undergoing primary percutaneous coronary intervention due to STEMI is an independent predictor of mortality and adds prognostic value, regardless of sex or rapidity of revascularization.