Abstract 3213: Infarct Transmurality and Infarct Size Assessed by Delayed Enhancement Magnetic Resonance Imaging: Association with Time-to-Treatment, ST-Segment Resolution, and TIMI-Flow Grades
Background The TIMI flow, ST-segment resolution (STR) and time-to-reperfusion (TTR) are associated with mortality in ST-elevation myocardial infarction (STEMI) after either fibrinolysis or percutaneous coronary intervention (PCI). As a result of excellent spatial resolution delayed enhancement magnetic resonance imaging (DE-MRI) allows assessment of infarct transmu-rality (IT). Whether these clinical, angiographic and ECG measures are also associated with infarct size (IS) and IT, has not yet been investigated.
Methods and results This study analyzed 134 STEMI patients randomized to prehospital fibrinolysis or prehospital initiated facilitated PCI. TTR, 90 min STR and TIMI-flow grades pre and post PCI were assessed. IS was determined as percentage of left ventricular mass (%LV) by DE-MRI and IT was analysed by a score ranging from 0 – 64. According to tertiles of TTR, IS was significantly smaller in the lowest with 5.1%LV (interquartile range [IQR] 2.0; 11.5) versus 11.3%LV (IQR 5.0; 15.6) in the middle and 14.4%LV (IQR 5.8; 15.6) in the upper tertile (p<0.001). Similarly, IT was significantly smaller in the lower (5.5; IQR 2.0; 10.0) in comparison to the middle (11.0; IQR 4.0; 18.0) and upper tertile (13.0; IQR 6.5; 17.5; p=0.001). STR also correlated significantly with IS and IT (p<0.001). In the groups with complete (>70%), intermediate (70–30%), and no (<30%) STR IS was 4.2%LV (IQR 1.6; 10.5), 13.6%LV (IQR 8.0; 16.4), and 12.4%LV (IQR 7.7; 17.9; p<0.001). In facilitated PCI patients the preinterventional TIMI flow correlated with IS (TIMI flow 0-I 10.8%LV [IQR 7.6; 17.3] vs. TIMI II-III 3.9%LV [IQR 0.9; 9.6]; p=0.002) and IT (TIMI flow 0-I 11.5 [IQR 8.0; 16.5] vs. 5.0 [IQR 2.0; 9.5]; p=0.003). In a multivariate model time-to-reperfusion was the strongest predictor of IS and IT (p=0.001) followed by type of reperfusion and STR (p=0.002).
Conclusions Early STR, TTR and TIMI flow before PCI correlate with IS and more importantly with IT, underlining the assumed pathophysiological link between early flow restoration and perfusion in the infarct related artery, which is well-known as the wave-front phenomenon. This may explain why these clinical, angiographic and electrocardiographic measures are associated with long-term survival.