Prognostic implications of quantitative evaluation of baseline Q-wave width in ST-segment elevation myocardial infarction

Abstract

Objectives: To evaluate quantitative relationships between baseline Q-wave width and 90-day outcomes in ST-segment elevation myocardial infarction (STEMI).

Background: Baseline Q-waves are useful in predicting clinical outcomes after MI.

Methods: 3589 STEMI patients were assessed from a multi-centre study.

Results: 1156 patients of the overall cohort had pathologic Q-waves. The 90-day mortality and the composite of mortality, congestive heart failure (CHF), or cardiogenic shock (p<0.001 for both outcomes) rose as Q-wave width increased. After adapting a threshold ≥40ms for inferior and ≥20ms for lateral/apical MI in all patients (n=3065) with any measureable Q-wave we found hazard ratios (HR) for mortality (HR: 2.44, 95% confidence interval (CI) (1.54-3.85), p<0.001) and the composite (HR: 2.32, 95% CI (1.70-3.16), p<0.001). This improved reclassification of patients experiencing the composite endpoint versus the conventional definition (net reclassification index (NRI): 0.23, 95% CI (0.09-0.36), p<0.001) and universal MI definition (NRI: 0.15, 95% CI (0.02-0.29), p=0.027).

Conclusions: The width of the baseline Q-wave in STEMI adds prognostic value in predicting 90-day clinical outcomes. A threshold of ≥40ms in inferior and ≥20ms for lateral/apical MI enhances prognostic insight beyond current criteria.

Keywords: Electrocardiogram; Prognosis; Q-wave; STEMI; Width.