Endomyocardial biopsy and clinical outcomes in acute myocarditis: a multicentre cohort study

초록

Background: Endomyocardial biopsy (EMB) remains the gold standard for the diagnosis of acute myocarditis (AM); however, its prognostic value has not yet been fully established. Purpose: We investigated the association between EMB and clinical outcomes, with a focus on fulminant myocarditis (FM) and histopathological subtype. Methods: We analysed a cohort of 841 AM patients across seven hospitals. Patients were categorized according to whether they underwent EMB (n = 268) or not (n = 573). The primary outcome was in-hospital death; the secondary outcome was a composite of all-cause death, cardiac transplantation, or left ventricular assist device implantation during long-term follow-up. Results: In-hospital mortality was lower in overall patients with EMB compared to those without (6.3% vs. 11.5%; P = .019). A similar reduction in in-hospital mortality was observed in the FM subgroup (11.3% vs. 23.7%; P = .002), despite a higher rate of extracorporeal membrane oxygenation use and lower requirements for vasoactive and inotropic agents in the EMB group. During a median follow-up of 447 days, the composite outcome was also lower in the EMB group among FM patients (P = .029). In multivariable analyses, EMB was independently associated with a lower risk of in-hospital death in both the overall cohort (hazard ratio [HR] 0.37; 95% confidence interval [CI] 0.21–0.66) and in the FM subgroup (HR 0.39; 95% CI 0.22–0.70). Outcomes did not differ substantially with histopathologic subtypes, although giant cell myocarditis showed worse prognosis. Conclusions: In patients with AM, EMB was associated with lower in-hospital mortality and improved long-term outcomes, particularly among those with FM. These findings support a proactive approach to EMB to enable timely diagnostic clarification and guide haemodynamic support.