Characteristics of histologically proven fulminant myocarditis managed with venoarterial extracorporeal membrane oxygenation: A post-hoc analysis of a Japanese nationwide study.

Background: Characteristics of histologically proven fulminant myocarditis (FM) managed with venoarterial extracorporeal membrane oxygenation (VA-ECMO) remain poorly understood. We aimed to identify factors associated with receiving VA-ECMO in patients with FM and with a composite endpoint (90-day mortality or heart transplantation) among VA-ECMO recipients.

Methods: This study used data from the Japanese Registry of Fulminant Myocarditis in a nationwide retrospective cohort of patients with histologically proven FM. Given the competing risk of death, admission factors associated with receiving VA-ECMO were analyzed using the Fine and Gray model. Among VA-ECMO recipients, factors associated with the composite endpoint were assessed by Cox proportional hazards regression.

Results: Of 337 patients (median age, 54 years; 40 % female), 177 (53 %) received VA-ECMO. The composite endpoint occurred in 44 % of VA-ECMO recipients, consisting entirely of mortality events. Female sex [subdistribution hazard ratio (SHR), 1.36; 95 % confidence interval (CI), 1.002-1.84], left ventricular ejection fraction <30 % (SHR, 1.66; 95 % CI, 1.21-2.28), ventricular tachycardia or ventricular fibrillation (SHR, 2.25; 95 % CI, 1.61-3.14), use of more vasopressors and inotropes (SHR, 1.28; 95 % CI, 1.10-1.48), or lactate level ≥ 2 mmol/L (adjusted risk ratio, 1.61; 95 % CI, 1.03-2.51) were associated with a higher risk of receiving VA-ECMO. Among VA-ECMO recipients, older age (HR, 1.20; 95 % CI, 1.0001-1.43), higher peak creatine kinase-MB level (HR, 1.24; 95 % CI, 1.13-1.36), and giant cell myocarditis (HR, 3.71; 95 % CI, 1.63-8.45) were associated with a higher risk of 90-day mortality.

Conclusions: This study characterized key factors associated with receiving VA-ECMO and 90-day mortality among VA-ECMO recipients, enhancing understanding of patient profiles and clinical courses in this high-risk population.