Effects of Baseline Q Waves and Reperfusion Strategy on Outcomes in Patients With ST-elevation Myocardial Infarction: Insights From the Vital Heart Response Registry.

BACKGROUND

Previous studies indicate the presence of baseline Q waves in patients with ST-elevation myocardial infarction (STEMI) is a stronger predictor of clinical outcomes than duration of symptoms. Whether reperfusion strategy modifies outcomes after accounting for baseline Q waves is unknown. We compared electrocardiogram reperfusion indices and clinical outcomes between a pharmacoinvasive and primary percutaneous coronary intervention strategy according to baseline Q wave status.

METHODS

We studied 967 patients from the Alberta STEMI Vital Heart Response (VHR) registry (2017-2021), stratified according to baseline Q wave and reperfusion strategy. Core laboratory ST-segment resolution (ST-R) was analyzed. The primary composite outcome was all-cause death, congestive heart failure, cardiogenic shock, and recurrent myocardial infarction.

RESULTS

Median symptom onset to first medical contact was 71 minutes; 21.8% of patients had baseline Q waves. Compared with patients with Q waves, those without had greater ST-R (79.0% vs 61.6%; P < 0.001; adjusted odds ratio [OR], 2.28; 95% confidence interval [CI], 1.66-3.14) and lower 30-day composite outcome (6.7% vs 13.7%; P = 0.001; adjusted hazard ratio, 0.68; 95% CI, 0.48-0.96). Regardless of baseline Q waves, the pharmacoinvasive strategy was associated with better ST-R than primary percutaneous coronary intervention (no Q waves: 85.6% vs 70.3%; P < 0.001; adjusted OR, 2.76; 95% CI, 1.82-4.19; Q waves: 69.5% vs 50.6%; P = 0.006; adjusted OR, 1.95; 95% CI, 1.06-3.59). At 1 year, the primary outcome was lowest among patients without baseline Q waves treated with pharmacoinvasive therapy (log-rank P < 0.001).

CONCLUSIONS

In STEMI patients who received timely reperfusion in our registry, baseline Q waves were associated with poorer reperfusion and worse clinical outcomes. A pharmacoinvasive strategy was associated with enhanced reperfusion irrespective of baseline Q waves, with the greatest value appearing to be in patients without Q waves.