Re-evaluation of intravenous steroid therapy for histologically confirmed fulminant myocarditis

The efficacy of intravenous steroids (IS) for fulminant myocarditis (FMP) remains controversial. We aimed to compare outcomes in FMP patients who received IS [IS(+)] and those who did not [IS(-)].

Data from 344 patients with histologically confirmed FMP requiring catecholamines or mechanical support were extracted from the Japanese Registry of Fulminant Myocarditis. The primary outcome was a composite of 90-day mortality and heart transplantation. Among the patients (median age 54, 40 % female), 195 received IS, 98 died within 90 days, and 16 died or underwent transplantation after 90 days. The IS(+) group had lower left ventricular ejection fraction and lower ratio of lymphocytic myocarditis, higher use of intra-aortic balloon pumping, Venoarterial extracorporeal membrane oxygenation (VA-ECMO), and intravenous immunoglobulin. Crude analysis showed worse 90-day outcomes in the IS(+) group (36.3 % vs. 19.2 %, P = 0.0021); however, after propensity score matching (PSM), outcomes were similar (26.2 % vs. 24.2 %; P = 0.95). Unadjusted Cox regression indicated worse outcomes with IS (HR 1.95, 95 % CI 1.26-3.04; P = 0.0026), but this was not significant after PSM (HR 1.02, 95 % CI 0.56-1.87; P = 0.95). Among low-risk patients, the IS(-) group showed better outcomes than the IS(+) group post-PSM (P = 0.0031). In the patients with VA-ECMO or ventricular assist devices, early IS (within 2 days of admission) showed comparable prognosis to delayed/no IS, with a trend toward better outcomes post-PSM.

IS effectiveness in FMP patients may vary, showing limited prognostic benefit overall. Careful consideration is warranted in its use for this population.