Clinical and magnetic resonance evolution of “infarct-like” myocarditis

AIMS: To analyse the clinical and magnetic resonance evolution of myocarditis in patients with an "infarct-like" presentation pattern. METHODS: The study is a retrospective analysis of 52 patients with clinical diagnosis of "infarct-like" myocarditis confirmed by CMR as acute myocarditis according to Lake Louise criteria and 6 months follow-up. The CMR protocol included T2-weighted (oedema), early (hyperaemia) and late (fibrosis/necrosis) gadolinium enhancement sequences, according to Lake Louise criteria. Clinical and radiological follow-up by CMR was performed after a median time interval of 6 months (interquartile range 5-8). Quantitative outcomes were checked for normality and compared with the non-parametric Wilcoxon's test for matched data. RESULTS: At the clinical follow-up all patients were free of symptoms and reported no cardiac complications. The CMR follow-up evidenced a significant increase of the ejection fraction (from 53 ± 6 to 55 ± 4%, p = 0.03), a decrease of the ventricular mass [from 67.0 (58.8-79.0) to 61.0 (54.0-67.0), p < 0.0001] without significant modification of the cardiac volume index (p = 0.26). No patient had residual oedema or capillary leakage: the T2 ratio decreased from 3.94 (3.00-4.86) to 0.98 (0.75-1.17) with p < 0.0001 and the Early gadolinium enhancement (EGE) ratio from 5.7 (4.8-6.5) to 2.9 (2.4-3.2) with p < 0.0001. Late gadolinium enhancement (LGE) persisted over the course of the follow-up in 48/52 patients, but with a significant reduction in every patient (LGE % from 34.3 ± 9.1 to 19.4 ± 6.6%; p < 0.0001). CONCLUSION: Patients diagnosed with "infarct-like" myocarditis, according to both clinical and CMR examinations may look forward to a positive evolution with a good prognosis. KEYWORDS: Acute myocarditis; Cardiovascular magnetic resonance; Outcome; “Infarct-like” myocarditis