Infarct-like versus Non-Infarct-like Clinical Presentation of Acute Myocarditis: Comparison of Cardiac Magnetic Resonance (CMR) Findings

Abstract

Background: The clinical presentation of acute myocarditis (AM) is widely variable, ranging from a subclinical disease to an infarct-like syndrome. Cardiac magnetic resonance (CMR) has become the reference non-invasive diagnostic tool for suspected AM, allowing the identification of the various hallmarks of myocardial inflammation (edema, fibrosis, and hyperemia). The aim of the study was to investigate any differences in morphological, functional, and tissue characterization CMR parameters between infarct-like AM in patients with unobstructed coronary arteries and non-infarct-like AM, diagnosed according to the original Lake-Louise Criteria (LLC); Methods: We retrospectively selected 39 patients diagnosed with AM according to LLC, divided into 2 groups according to the clinical presentation: infarct-like in group 1 patients and non-infarct-like in group 2 patients. CMR morphologic, functional, and tissue characterization parameters were analyzed and compared. Results: In group 1, CMR tissue characterization parameters were mainly altereda in septal location with mesocardial myocardial involvement; in group 2, CMR tissue characterization parameters were mainly altered in a lateral location with subepicardial myocardial involvement mainly at the mid-cavity. No significant differences in morphological or functional parameters were observed between the two study groups. Conclusions: Our results showed differences in the localization and distribution of myocardial tissue damage assessed by CMR among forms of AM accompanied by an infarct-like clinical presentation compared with non-infarct-like presentations of AM. The mechanisms underlying the different preferential sites of damage observed in our study are not known, and we do not exclude the possibility of their prognostic implications.