Clinical and Economic Evaluation of Impella Treatment for Fulminant Myocarditis　― A Preliminary Retrospective Cohort Study in Japan ―

BACKGROUND: Fulminant myocarditis (FM) is rare but has an extremely poor prognosis. Impella, a catheter-based heart pump, is a new therapeutic strategy, but reports regarding its health economics are lacking. METHODS AND RESULTS: This retrospective cohort study compared Impella treatment (Group I) with existing treatments (Group E) using medical data collected from October 2017 to September 2021, with a 1-year analysis period. Cost-effectiveness indices were life-years (LY; effect index) and medical fee amount (cost index). Results were validated using probabilistic sensitivity analysis. The incremental cost-effectiveness ratio (ICER) was calculated using quality-adjusted LY (QALY) and medical costs. Each group included 7 patients, and more than half (57.1%) received combined Impella plus extracorporeal membrane oxygenation. There was no significant difference between Groups I and E in 1-year mortality rates (28.6% vs. 57.1%, respectively) or LY (mean [±SD] 163.1±128.3 vs. 107.8±127.3 days, respectively), but mortality risk was significantly lower in Group I than Group E (95% confidence interval 0.02-0.96; P<0.05). Compared with Group E, Group I had higher total costs (9,270,597±4,121,875 vs. 6,397,466±3,801,364 JPY/year; P=0.20) and higher cost-effectiveness (32,443,987±14,742,966 vs. 92,637,756±98,225,604 JPY/LY; P=0.74), which was confirmed in the sensitivity analysis. ICER probability distribution showed 23.2% and 51.5% reductions below 5 million and 10 million JPY/QALY, respectively. CONCLUSIONS: Impella treatment is more cost-effective than conventional FM treatments. Large-scale studies are needed to validate the added effects and increasing costs.