Influence of time-to-treatment, TIMI-flow grades, and ST-segment resolution on infarct size and infarct transmurality as assessed by delayed enhancement magnetic resonance imaging.

Aims: The time-to-treatment, ST-segment resolution (STR), and TIMI-flow might be associated with infarct size (IS) and infarct transmurality in humans. Delayed enhancement magnetic resonance imaging (DE-MRI) has excellent spatial resolution to uncover these relations.

Methods And Results: This study analysed 135 ST-elevation myocardial infarction (STEMI) patients randomized to prehospital fibrinolysis or prehospital initiated facilitated percutaneous coronary intervention (PCI). Reperfusion-times, 90 min STR, and TIMI-flow grades were assessed. IS at 6-month follow-up was determined as percentage of left ventricular mass (% LV). Transmurality was defined if segments exceeded > 50% DE. The median time-to-treatment was 93 min [interquartile range (IQR) 66.5; 158.8] for prehospital fibrinolysis and 85 min (IQR 60.0; 143.5) for facilitated PCI patients (P = 0.35). In facilitated PCI, the pre-interventional TIMI-flow correlated with IS [TIMI 0-1 10.8% LV (IQR 7.6; 17.3) vs. TIMI 2-3 3.9% LV (IQR 0.9; 9.6); P = 0.002] and segments with transmurality 1.5 (IQR 0.0; 3.0) vs. 0 (IQR 0.0; 1.5; P = 0.02). In a multivariable model, incomplete STR < 70% was the strongest predictor of high IS [odds ratio (OR) 6.96, P < 0.001] and transmurality (OR 5.71, P < 0.001) followed by time-to-treatment delay (OR/30 min, 1.24; P = 0.01 for high IS and 1.23, P = 0.01 for transmurality).

Conclusion: Time-to-treatment, STR, and TIMI-flow correlate with IS and transmurality underlining the assumed pathophysiological link between early flow restoration and perfusion in the infarct-related artery.