321 Differentiating Myocarditis from Myocardial Infarction in Infarct-Like Presentations Using Troponin and Cardiac MRI

Abstract

Infarct-like presentations are usually well differentiated on cardiac MRI by the pattern of late gadolinium enhancement (LGE), but transmural LGE can occur. The aim of this study is to determine if there is a difference in the relationship between the peak troponin and the amount of LGE in acute myocarditis and acute myocardial infarction in infarct-like presentations. If so, we aim to define a ratio that can be used as an objective differentiator. 111 patients across two sites were included as they had an infarct-like presentation, troponin rise and cardiac MRI between 2010 and 2018. CVI42 was used for MRI tissue characterisation. Of the 51 patients with myocarditis, 36 (59%) were male and the mean peak troponin I was 10872 ng/L. Of the 61 patients with a myocardial infarction, 47 (77%) were male and the mean peak troponin I was 74133 ng/L. Preliminary results from the analysis of 26 patients showed the LGE mass was significantly greater in the infarct group compared to the myocarditis group (23.8 vs 9.8 grams, p=0.02). There was also a significant greater ratio of peak troponin to LGE mass in the infarct group compared with the myocarditis group (mean ratio 4306:1 vs 557:1, p=0.01). Preliminary results suggest there is a significantly greater peak troponin for the same amount of LGE in infarction compared with myocarditis. Further analysis is underway to confirm these findings over the larger sample size, and validate an objective cut off to differentiate myocarditis from infarction.