Reevaluation of Intravenous Steroid Therapy for Histologically Confirmed Myocarditis with Fulminant Presentation: Insights from the Japanese Registry of Fulminant Myocarditis

Abstract

Background: The efficacy of intravenous steroids (IS) in patients with fulminant myocarditis presentation (FMP) remains controversial. We aimed to compare the clinical outcomes between patients with FMP who received IS (IS(+)) and not received IS (IS(-)). Methods: From the Japanese Registry of Fulminant Myocarditis, we extracted the data of patients requiring catecholamines or mechanical support, with histologically confirmed FMP. The primary outcome was a composite of mortality and heart transplantation within 90 days. We assessed the impact of IS on outcomes using the Kaplan-Meier method, log-rank test, and Cox regression analysis. Patients were categorized according to the number of prognostic factors (age ?55 years, non-sinus rhythm, left ventricular ejection fraction [LVEF] <40% at admission, ventricular tachycardia/fibrillation on the first day, and the presence of giant cell myocarditis); the relationship between the 90-day prognosis and IS use within these categories. Results: Of 344 patients (median age: 54 years; 40% female), 98 died within 90 days and 16 died after 90 days. IS was administered in 195 patients. The proportion of patients with lymphocytic myocarditis and LVEF were lower in the IS(+) group than in the IS(-) group. Intra-aortic balloon pumping, extracorporeal membrane oxygenation, and intravenous immunoglobulin administration were more common in the IS(+) group than in the IS(-) group. Analysis of the entire cohort indicated worse 90-day outcomes in the IS(+) group than in the IS(-) group (36.3% vs. 19.2%, P=0.0021); however, there was no substantial difference after propensity score matching (PSM; 26.2% vs. 24.2%; P=0.95). On unadjusted Cox regression, IS use was associated with worse 90-day outcomes (hazard ratio, 1.95 [95% confidence interval, 1.26-3.04]; P=0.0026). However, after PSM, this association was no longer significant (1.02 [0.56-1.87], P=0.95). Similar results were observed among patients with lymphocytic myocarditis. The prognosis was notably worse with IS administration than without IS administration among low-risk patients (P=0.001). Conclusions: IS may not provide prognostic advantages for patients with FMP. The adverse effects of IS might be more pronounced in low-risk patients.