Fulminant lymphocytic myocarditis mimicking ST-elevation myocardial infarction:

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A 74-year-old lady with hypertensive cardiomyopathy and COPD (GOLD II) was admitted to our hospital because of angina and worsening dyspnoea over the last 3 days. The admission electrocardiogram showed ST-elevation and Q waves in the antero-lateral leads, compatible with subacute anterior myocardial infarction. Troponin I was 52 μg/L and CK 2061 U/L. Urgent coronary angiography excluded coronary artery disease, so transthoracic echocardiography (TTE) and cardiac magnetic resonance (CMR) were performed. TTE showed diffuse in left ventricular hypokinesia and increased thickness of the antero-septal wall, while CMR revealed a corresponding extensive myocardial oedema and necrosis with predominant sub-epicardial/mid-myocardial distribution highly suggestive of a myocarditis pattern. The diagnosis of fulminant lymphocytic myocarditis was confirmed by myocardial biopsy. The ejection fraction dropped from 45 to 15% but recovered 3 weeks later (temporary ECMO support) until 40%. PanelA: ST-elevation in V1–V4 and DI–aVL leads (red boxes), admission ECG. Panel B: significative QRS widening and diffuse ST-elevation (yellow boxes), day 4 ECG. Panels C, D and F: short-axis (C) and three-chamber long-axis (D) MR T2 mapping with extensive circumferential sub-epicardial myocardial oedema, particularly on the right-ventricular side of the interventricular septum (green arrows; the light purple myocardium marks myocardial oedema with T2 value increased to 68 ms). Three-chamber, long-axis MR late enhancement view (Panel F) with an analogous distribution of myocardial necrosis (blue arrows). Panel E: myocardial biopsy showing diffuse lymphocytic–histiocytic infiltrate and myocyte necrosis.

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