Abstract 203: Reproducibility of Myocardial Salvage in Acute Myocardial Infarction by the Use of Contrast-Enhanced Magnetic Resonance Imaging
Background: Myocardial salvage assessed by cardiac MRI is a new technique which might be used as a surrogate endpoint to reduce the sample size in studies comparing different reperfusion strategies in AMI. So far reproducibility of myocardial salvage has not been evaluated appropriately. The aim of this study was to evaluate the reproducibility of myocardial salvage in acute myocardial infarction (AMI) by T2-weighted and delayed enhancement (DE) magnetic resonance imaging (MRI).
Methods: In 20 patients with AMI and successful mechanical reperfusion breath-hold T2-weighted (area at risk) and DE (infarct size) images were acquired repeatedly on 2 consecutive days to assess myocardial salvage index (area at risk-infarct size/area at risk). Reproducibility, interobserver, and intraobserver variabilities were assessed and compared by Bland-Altman methods.
Results: The area at risk was 47.4±11.7% of left ventricular mass (%LV) and the infarct size 20.2±9.6%LV. The corresponding myocardial salvage index was 57.7±14.9 (range 23.4–75.8). Area at risk difference (bias) between scan I and scan II was 1.2%LV and limits of agreement were ±7.5%LV. The results for infarct size were 0.5%LV ±2.6%LV limits of agreement. The resulting bias for myocardial salvage index was −0.3 with limits of agreement of ±5.0. Intra- and interobserver variability was low with a mean bias of −0.7 (limits of agreement ±4.6) and −0.0 (limits of agreement ±4.7), respectively.
Conclusions: Myocardial salvage index assessment by MRI is an excellent tool with excellent repeatability in AMI. It has therefore the potential to serve as a surrogate endpoint to uncover advantages of new reperfusion strategies.