[Long term prognosis of fulminant myocarditis and predictors related to impaired cardiac function post discharge]

Objective: To compare the long-term prognosis of fulminant myocarditis (FM) and non-fulminant myocarditis (NFM) patients who survived and discharged from hospital, and to explore the factors associated with the long-term prognosis and impaired cardiac function. Methods: This study was a retrospective study. Consecutive patients with acute myocarditis hospitalized in Tongji Hospital from January 2017 to December 2020 were enrolled and divided into FM group and NFM group according to the type of myocarditis. Then, patients in the FM group were further divided into normal cardiac function group and impaired cardiac function group according the left ventricular ejection fraction (LVEF). All patients with acute myocarditis were treated with antiviral, immunomodulatory, immunosuppressive medications and symptomatic and supportive treatment, while FM patients were treated with comprehensive treatment plan. Clinical data at admission of enrolled patients were collected through the electronic medical record system. Patients were clinically followed-up at 1, 3, 6 and 12 months, then once a year after discharge by clinical visit. The primary endpoints included major cardiovascular events, impaired cardiac function was defined by LVEF<55%. Kaplan-Meier survival curve was used to analyze the occurrence of LVEF<55% and left ventricular enlargement during the follow-up of patients in FM group and NFM group, and Log-rank test was used for comparison between groups. Cox regression model was used to analyze the risk factors of impaired cardiac function in patients with FM during follow-up. Results: A total of 125 patients with acute myocarditis were enrolled (66 in FM group and 59 in NFM group). Compared with NFM group, the proportion of FM patients with the lowest LVEF<55% during hospitalization was higher (P<0.01), and the recovery time of normal LVEF during hospitalization was longer (P<0.01). The proportion of LVEF<55% at discharge was similar between the two groups (P=0.071). During the follow-up of 12 (6, 24) months, 1 patient (1.5%) died due to cardiac reasons in FM group after discharge, 16 patients (24.2%) had sustained LVEF<55% after discharge, and 8 patients (12.1%) had left ventricular enlargement. In NFM group, 3 patients (5.1%) had sustained LVEF<55%, and 1 patient (1.7%) had left ventricular enlargement. Kaplan-Meier survival curve analysis showed that the incidence of sustained LVEF<55% in FM group was higher than that in NFM group (P=0.003), and the incidence of left ventricular enlargement was also higher than that in NFM group (P=0.024). Subgroup analysis of patients in the FM group showed that, compared with the normal cardiac function group, the time from onset to admission was shorter (P=0.011), the proportion of LVEF<55% at discharge was higher (P=0.039), the proportion of coronary angiography was higher (P=0.014), and the LVEF recovery time during hospitalization was longer (P=0.036) in FM patients with impaired cardiac function. Multivariate Cox regression analysis showed that longer LVEF recovery time during hospitalization was an independent risk factor for cardiac function impairment after discharge of FM patients (HR=1.199, 95%CI 1.023-1.406, P=0.025). Conclusions: The incidence of reduced LVEF is significantly higher in FM patients than that in NFM patients. Longer LVEF recovery time during hospitalization is an independent risk factor for cardiac function impairment in FM patients after discharge.