Abstract 2396: Predictors and Implications of Q-waves in ST-Elevation Myocardial Infarction: A Contemporary Perspective from the Global Registry of Acute Coronary Events
Objectives: Q-waves in ST-elevation myocardial infarction (STEMI) may have adverse pathologic and prognostic implications. Their frequency, predictors, and implications have not been evaluated in the current era of increasingly rapid reperfusion and greater use of primary percutaneous coronary intervention (PCI).
Methods: We used data from an observational study of 15,038 consecutive patients (the Global Registry of Acute Coronary Events) presenting with STEMI between 1999 and 2005. Transfer patients and those with prior myocardial infarction were excluded. Clinical variables were compared in patients who developed presumed new Q-waves versus those who did not. Differences reported are statistically significant at α = 0.05.
Results: Q-waves occurred during admission in 47% of patients, and were noted on the presenting ECG in 26%. There were differences in treatment (P<0.001 for trend) among patients with Q-waves versus those without, including use of PCI (30% vs 27%), fibrinolytics (32% vs 22%), or no reperfusion therapy (33% vs 48%). Frequency of Q-wave development decreased significantly between 1999 and 2005, from approximately 49% to 40% (P<0.001 for trend). Univariate analyses showed Q-waves were associated with greater in-hospital heart failure (18% vs 14%), cardiogenic shock (7.3% vs 5.5%), and malignant arrhythmia or arrest (11% vs 9.6%) (all P<0.001 for trend), with no difference in hospital mortality. Logistic regression indicated Q-wave development was associated with male gender, lack of long-term aspirin or other evidence-based drugs, lack of prior coronary artery disease, lack of prior heart failure, diabetes, and tobacco use. Logistic regression also showed a large reduction in hospital mortality when acute use of evidence-based medications (odds ratio 0.41, 95% confidence interval 0.26–0.64) or reperfusion therapy (OR 0.51, 95% CI 0.32–0.82) preceded Q-wave development.
Conclusion: Although there is a decreasing incidence of Q-waves in STEMI patients in the current era, Q-waves still have prognostic implications. Use of evidence-based medications and reperfusion therapy before Q-wave development are associated with a dramatic improvement in survival.