Outcome of patients with myocarditis according to clinical risk classification and cardiac magnetic resonance parameters
Authors: Di Lisi D , Madaudo C , Scelfo D , Carmina MG , Di Gesaro G , Zarcone A , Guarino T , D"ardia G , Vizzini MC , Lunetta M , Clemenza F , Galassi AR , Novo G 
Published: February 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Myocarditis is an inflammatory disease defined by precise histological, immunological and immunohistochemical criteria and characterized by a great heterogeneity of presentation. The early evaluation of the possible outcomes and long-term prognosis of patients with myocarditis remains a challenge for the cardiologists, with repercussions on the most appropriate therapeutic choices for the patient.

Purpose
The purpose of this study was to analyze the outcomes of patients with acute myocarditis using the multiparametric integration of clinical, echocardiographic and cardiac magnetic resonance imaging data.

Methods
We retrospectively collected data from 127 patients admitted for acute myocarditis from 2011 to 2021 in 3 Sicilian hospitals. The main anamnestic information, risk factors and clinical manifestations at onset, electrocardiogram, echocardiogram including the global longitudinal strain (GLS) measurement and morphofunctional parameters at cardiac magnetic resonance (CMR), presence of edema and delayed enhancement (DE) and myocardial segments involved were collected. Patients were stratified according to the classification proposed by the group of Trieste group in 2017 in high-risk, intermediate-risk patients and low-risk patients. The occurrence of adverse events during follow up in the 3 groups was evaluated.

Results
High-risk patients had a higher frequency of total adverse events (66.7%) compared to intermediate (14%) and low (16%) risk (p &lt; 0,0001), while no significant differences were observed regarding relapses. Intermediate-risk patients had a tendency to develop events comparable to low-risk patients. At baseline, FE was 34.02 ± 12.98% for high risk patients vs 59.24 ± 3.82% low risk vs 58.41 ± 5.21% intermediate risk (p &lt; 0,0001). The mean GLS was -16 ± 4.43 for high risk patients vs -19 ± 2.37 low risk vs -18 ± 2.06 intermediate risk (p &lt; 0,0271). 78% high-risk patients, 72% low-risk patients, and 75% intermediate-risk patients had edema at baseline MRI (p &lt; 0,0249). 90% patients with high risk, 85% patients with low risk and 97% patients with intermediate risk had DE at baseline MRI (p &lt; 0,0001). In intermediate-risk patients, an association was observed between the number of segments affected by DE at baseline MRI and the occurrence of events (p &lt;0.013). The number of segments involved by DE that, with the best sensitivity and specificity, identifies the subjects most likely to develop events was 2.5 [AUC 0.5; p-value of 0.24]. The sum of the segments involved by DE at MRI statistically correlated with the detection of a reduced mean GLS (p &lt; 0.009).

Conclusions
Our study confirms the usefulness of the clinical prognostic classification of the Trieste group. Intermediate-risk patients, who still represent a gray area from a prognostic point of view, have shown to have an overall good prognosis, not significantly different since low-risk patients. The extent of edema and the extent of DE at baseline are the major predictors of events.