Clinical impact and prognostic significance of pericardial involvement in acute myocarditis: insights from a CMR study

This study aims to investigate the demographic, laboratory, clinical, and cardiovascular magnetic resonance (CMR) correlates of pericardial involvement, as well as its impact on outcomes in patients with acute myocarditis. This retrospective study analyzed 141 consecutive patients diagnosed with acute myocarditis (113 males, mean age 41.12 ± 19.64 years) who met the diagnostic criteria for clinically suspected myocarditis with an acute presentation and underwent CMR scans adhering to the update Lake Louise Criteria. Pericardial involvement was identified based on the presence of pericardial enhancement on T2-STIR and/or LGE sequences. Among the acute myocarditis patients enrolled, 34 (24%) showed pericardial involvement. No significant differences were observed in terms of age, sex, clinical presentation, and ventricular function and volume between patients with and without pericardial involvement. Patients with pericardial involvement demonstrated higher levels of C-reactive protein, as well as more impaired reservoir and conduit atrial strain mechanisms compared to those without pericardial involvement (p = 0.014, p = 0.001; and p = 0.001, respectively). On multivariate analysis, reservoir and conduit atrial strain were independently linked to pericardial involvement (β = -3.384, p = 0.001; β = -3.305, p = 0.001). Furthermore, pericardial involvement in patients with acute myocarditis was not a determinant of cardiac adverse events during follow-up. Pericardial involvement is not uncommon in acute myocarditis patients and is independently associated with atrial strain parameters, but it does not increase the risk of adverse cardiovascular events during follow-up.