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

BackgroundThe 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(-)). MethodsFrom 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 [&ge;]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. ResultsOf 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). ConclusionsIS may not provide prognostic advantages for patients with FMP. The adverse effects of IS might be more pronounced in low-risk patients. RegistrationURL: https://www.umin.ac.jp/ctr; Unique identifier: UMIN000039763. Clinical PerspectiveO_ST_ABSWhat Is New?C_ST_ABSO_LIIntravenous steroids were commonly administered in more severe cases, particularly in patients diagnosed with eosinophilic myocarditis or giant cell myocarditis. C_LIO_LIWhile the prognosis was poorer in patients who received intravenous steroids than in those who did not, the outcomes were similar when comparing cohorts matched on patient background factors. C_LIO_LINotably, prognosis was worse in low-risk patients who were administered intravenous steroids. C_LI What Are the Clinical Implications?O_LIAdministering intravenous steroids might not yield any prognostic advantage for patients with fulminant myocarditis. Further, the potential negative effects of intravenous steroids appear to be more pronounced in low-risk patients. C_LIO_LIThus, clinicians should be cautious about administering intravenous steroids, especially in those identified as low-risk. C_LI