Changes in Cardiac Function Following Fulminant Myocarditis.

Background: The natural history of myocardial dysfunction in patients with fulminant myocarditis is poorly understood. This study aims to evaluate changes in cardiac function in patients with fulminant myocarditis using a nationwide registry in Japan.

Methods: This retrospective cohort study included patients with biopsy-proven fulminant myocarditis and available for left ventricular ejection fraction (LVEF). We described the LVEF on admission, at discharge, and 1 year after discharge. We divided patients into 2 groups based on LVEF at discharge (reduced ejection fraction of <50% or preserved ejection fraction of ≥50%) and analyzed changes in LVEF and prognosis according to groups.

Results: We included 214 patients (the median [first-third quartiles] age of the cohort was 48 [35-62] years, and 63 [38%] were female). Of 153 patients available for LVEF at 1 year, the median (first-third quartiles) LVEF increased from 33% (21-45%) on admission to 59% (49-64%) at discharge and further to 61% (55-66%) at 1 year. Of 153 patients, 45 (29%) and 22 (14%) had LVEF <50% at discharge and at 1 year, respectively. Comparisons between patients with LVEF <50% and those with LVEF ≥50% demonstrated that the former group had a higher adjusted probability of death or heart transplantation (hazard ratio, 8.19 [95% CI, 2.13-31.5]; =0.002).

Conclusions: Some patients with fulminant myocarditis had left ventricular dysfunction in the chronic phase. Patients with reduced left ventricular function at discharge had a worse prognosis than those with preserved left ventricular function.

Registration: URL: https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000045352; Unique identifier: UMIN000039763.