Association Between Vasoactive Inotropic Score and Clinical Outcomes in Patients With Fulminant Myocarditis

Background and Objectives: This study aimed to evaluate the prognostic value of the vasoactive inotropic score (VIS) in patients with fulminant myocarditis according to the application of venoarterial-extracorporeal membrane oxygenation (VA-ECMO). Methods: This study retrospectively analyzed 417 patients with biopsy-proven or clinically suspected fulminant myocarditis from 7 hospitals in Korea. The primary outcome was a composite of all-cause death, heart transplantation, or the use of left ventricular assist device (LVAD) at 1 year. Results: The median VIS was 19.9, and 217 (52.0%) patients received VA-ECMO. The primary outcome occurred in 105 patients (26.7%). All-cause death, heart transplantation, and the implantation of LVAD occurred in 81 (20.7%), 30 (8.7%), and 1 (0.3%) patients, respectively. VIS was associated with the risk of the primary outcome in both patients treated with VAECMO (hazard ratio [HR], 1.017 for every 10-point increase; 95% confidence interval [CI], 1.007–1.028; p=0.001) and patients without VA-ECMO (HR, 1.128 for every 10-point increase; 95% CI, 1.079–1.179; p<0.001), but the effect was greater in patients without who did not receive VA-ECMO (interaction p<0.001). Furthermore, the predictive performance of VIS for the primary outcome was significantly lower in patients with VA-ECMO than in those without VA-ECMO (C-index, 0.555 vs. 0.780; p value for C-index comparison, 0.002). Conclusions: In patients with fulminant myocarditis, the prognostic value of VIS was more prominent in patients without VA-ECMO than in patients with VA-ECMO. These findings suggest that the prognostic value of VIS is weakened under the influence of VA-ECMO. Trial Registration: ClinicalTrials.gov Identifier: NCT05933902.