1083A comparison of sequences to quantitate myocardial salvage following STEMI

Abstract

Background: Myocardial salvage (MS) is a predictor of prognosis following STEMI and is frequently used as an endpoint in clinical trials. However, the CMR sequence for assessing myocardial oedema, used to calculated MS, following STEMI is controversial. T2-STIR is in widespread clinical use but can lack robustness. The hybrid TSE-SSFP sequence (ACUT2E) has emerging data to support it as a more reproducible method for oedema assessment. A novel T2 mapping method is also available to determine myocardial oedema. More recently, imaging early after gadolinium contrast administration (EGE) has been suggested as an alternative to detect myocardial oedema following STEMI. The aim of this study was to assess which of the CMR sequences for detecting myocardial oedema and, therefore, quantitating MS following STEMI is most robust. Methods: 40 patients day 2 following STEMI were prospectively enrolled into the study. All patients had 2 CMR scans on the same day at least 6 hours apart. 3 slices repeated using all 4 sequences followed by LGE imaging. Images were analysed offline by 2 observers blinded to other sequence analysis results. The images were analysed using semi-automated software, and the MS was expressed as a mass (g). Inter-observer, intra- observer and inter-scan agreement was assessed using the Bland Altman method. Results: Bland Altman plots for inter-observer, inter-scan and intra-observer agreements were acquired for MS calculated by the 4 sequences. ACUT2E appears the least reproducible of the 4 techniques, with T2 mapping with the best intra, inter- observer and inter-scan agreement. Inter-observer (T2-STIR bias -0.9 +/- 9.6; ACUT2E bias -9.8 + /-11.6; T2 map bias -3.8 + /-4.7; EGE bias -5.3 + /-5.9). Inter-scan (T2-STIR bias 0.7 + /-6.4; ACUT2E bias -7.7 + /-11.9; T2 map bias 2.9 + /-4.2; EGE bias 1.1 + /-4.9). Intra-observer (T2-STIR bias 0.6 + /-6.0; ACUT2E bias -6.3 + /-10.1; T2 map bias 2.1 + /-3.3, EGE bias 1.7 + /-2.9). Conclusions: The limitations of T2-STIR are well documented. This is the first study that systematically compared all available techniques to determine the most robust sequence for measuring myocardial oedema and, therefore, quantitate MS following STEMI. This study demonstrates that T2 mapping is a robust methods to be used for surrogate endpoints in clinical studies.