AIMS
We aimed to evaluate the impact of delay from diagnostic pre-hospital electrocardiogram (ECG) to wiring of the infarct-related vessel (ECG-to-wire) >120 minutes on cardiovascular magnetic resonance (CMR) markers of reperfusion success and clinical outcome in patients with ST-segment elevation myocardial infarction (STEMI).
METHODS AND RESULTS
We included 1,492 patients in the analyses of clinical outcome. CMR was performed in 748 patients to evaluate infarct size and myocardial salvage. In total, 304 patients (20%) had ECG-to-wire >120 minutes, which was associated with larger acute infarct size (18% [interquartile range (IQR), 10-28] vs. 15% [8-24]; p=0.022) and smaller myocardial salvage (0.42 [IQR 0.28-0.57] vs. 0.50 [IQR 0.34-0.70]; p=0.002). However, 33% of the patients with ECG-to-wire >120 minutes still had a substantial myocardial salvage ≥0.50. In a multivariable analysis, ECG-to-wire >120 minutes was associated with an increased risk of all-cause mortality and heart failure (hazard ratio 1.61, 95% confidence interval [CI] 1.14-2.26, p=0.007).
CONCLUSIONS
ECG-to-wire >120 minutes was associated with larger infarct size, smaller myocardial salvage and a poorer clinical outcome in STEMI patients transferred for primary percutaneous coronary intervention. However, myocardial salvage was still substantial in one third of patients treated beyond 120 minutes of delay.