Myocarditis with preserved left ventricular ejection fraction in-hospital convalescent phase: insights from CMR and myocardial strain analysis

Background The convalescent phase of myocarditis in patients with preserved left ventricular ejection fraction remains poorly characterized. Persistent myocardial inflammation may elevate the risk of major adverse cardiovascular events (MACE). Conventional assessment of left ventricular function is limited in sensitivity, whereas myocardial strain analysis provides detection of subclinical myocardial dysfunction. Methods In this retrospective study, 317 patients with myocarditis underwent cardiac magnetic resonance (CMR). Feature-tracking CMR was used to quantify ventricular and atrial strain parameters. Late gadolinium enhancement (LGE) was assessed for myocardial tissue characterization. Patients were followed clinically, with MACE as the primary endpoint. Results Among 146 patients included in the final analysis (71 male; mean age 26 ± 16 years), 36 experienced MACE. LGE was present in 54.8% of patients. In LGE positive patients, one, two, and three or more segments were involved in 6.25%, 16.25%, and 77.50% of cases, respectively. In univariable and multivariable Cox regression analyses, left ventricular global radial strain ( p = 0.026) and left ventricular diastolic middle circumferential strain rate ( p = 0.014) emerged as independent predictors of MACE. Conclusions Left ventricular global radial strain may reflect persistent myocardial inflammation during convalescence from myocarditis. Myocardial strain parameters provide incremental prognostic value beyond conventional functional measures.