Abstract 13667: Impact of Time-to-Reperfusion on Infarct Size, Microvascular Obstruction and Infarct Transmurality Assessed by MRI in STEMI Reperfused by Primary PCI
Introduction: Previous studies evaluating the relation of time-to-reperfusion and myocardial damage in patients with STEMI reperfused by primary PCI achieved inconsistent Results and are limited due to small and highly-selected study samples. Therefore, we investigated the impact of time-to-reperfusion on infarct size (IS), microvascular obstruction (MO) and infarct transmurality assessed with MRI in a large prospective study cohort.
Methods: STEMI patients reperfused by primary PCI (n=322) within 720 min after symptom-onset underwent MRI at a median of 3 days after the index event (IQR 2–4). Patients were subcategorized into tertiles according to their time-to-reperfusion: lower tertile (< 175 min), middle tertile (175–320 min) and upper tertile (> 320 min). IS and MO were assessed 10–15 min after gadolinium-injection and analyzed quantitatively [% of left ventricular mass (%LV)]. Infarct transmurality was assessed by a score with late-enhancement grading as <25%, 25–50%, 50–75% and >75% transmurality analyzing all 17 LV segments.
Results: The median time-to-reperfusion was 230 min (IQR 153;390). IS and MO did not increase significantly with longer time-to-reperfusion (IS: 13.6 %LV [IQR 6.6;26.2] for <175 min, 20.2 %LV [IQR 10.8;29.8] for 175–320 min and 21.6 %LV [IQR 12.8;29.9] for >320 min; p=0.10; MO: 0.5 %LV [IQR 0;1.5] for <175 min, 0.7 %LV [IQR 0;1.8] for 175–320 min and 0.7 %LV [IQR 0.1;1.6] for >320 min; p=0.37). In contrast to MO and IS, the infarct transmurality score progressed significantly with increasing ischemic time (2.7 [IQR 2.1;3.1] for <175 min, 3.0 [IQR 2.4;3.4] for 175–320 min and 3.2 [IQR 2.8;3.5] for >320 min; p<0.001). In multivariable analysis including parameters such as post-PCI TIMI-flow, ST-segment- resolution and maximum creatine kinase levels, time-to-reperfusion was identified as an independent predictor for transmural infarction defined as infarct transmurality >50% (OR for lower vs. upper tertile: 5.40, 95%CI 2.13;13.60, p<0.001; OR for middle vs. upper tertile: 2.71, 95%CI 1.06;6.93, p=0.04).
Conclusions: In STEMI patients reperfused by primary PCI infarct transmurality is independently associated with time-to-reperfusion, whereas IS and MO do not progress significantly with more prolonged ischemic time.
- © 2010 by American Heart Association, Inc.