LAUSR

Fulminant myocarditis (FM) is a form of acute myocarditis characterized by severe left ventricular (LV) dysfunction requiring inotropes and/or mechanical circulatory support. Based on a retrospective single-center study published in 2000, patients with FM were considered to have better outcomes than those affected by acute non-fulminant myocarditis (NFM) presenting with LV systolic dysfunction (LVSD). Recently, this tenet was challenged, though substantial disagreement still exists. Aim of the present study is to provide additional evidence on the outcome of FM and to ascertain if patient stratification based on the main histologic subtypes can provide additional prognostic information. Two hundred and twenty patients (median age 42 years, 46.3% female) with histologically proven acute myocarditis (onset of symptoms <30 days) presenting with LVSD were included in a retrospective, international registry comprising 16 tertiary hospitals in the United States, Europe, and Japan. The primary endpoint was the occurrence of cardiac death or heart transplant (HTx) within 60 days from admission and at long-term follow-up. Patients with FM (N=165) had significantly higher rates of cardiac death and HTx compared with those with NFM (N=55), both at 60 days (28.0% vs. 1.8%, p=0.0001) and at 7-year follow up (47.7% vs. 10.4%, p<0.0001; Figure). At Cox-multivariate analysis, the histologic subtype emerged as a further variable affecting outcome in FM patients, with giant cell myocarditis having a significantly worse prognosis compared with eosinophilic and lymphocytic myocarditis both at 60 days (62.5% vs. 26.3% vs. 21.0%) and at 3 years (81.3% vs. 39.9% vs. 37.3%, overall p<0.0001). In a sub-analysis including only adults with lymphocytic myocarditis, the main endpoints occurred more frequently in FM compared with NFM both at 60 days (19.5% vs. 0%, p=0.005) and up to 7 years (41.4% vs. 3.1%, p=0.0004). Outcome of FM vs NFM The results of this international registry confirm that patients with FM have higher rates of cardiac death and HTx both in the short and long-term compared with patients with NFM. Furthermore, we provide evidence that the histologic subtype of FM carries independent prognostic value, highlighting the need for timely endomyocardial biopsy in this condition. None