BACKGROUND: Among patients with dilated cardiomyopathy (DCM), myocardial inflammation and fibrosis are risk factors for poor clinical outcomes. Here, we investigated the combined prognostic value of these two factors, as evaluated using myocardial biopsy samples. METHODS: This retrospective and multicentre study included patients with DCM-defined as LVEF of ≤45% and left diastolic diameter of >
112% of predicted value, without evidence of secondary or ischaemic cardiomyopathy. In myocardial biopsy samples, inflammatory cells were counted using immunohistochemistry, and Masson's Trichrome staining was performed to quantify the myocardial fibrosis as collagen area fraction (CAF). Higher myocardial inflammation was defined as leucocytes of ≥14/mm², including ≤4 monocytes/mm², with CD3 RESULTS: A total of 255 DCM patients were enrolled (average age, 53.1 years
78% males). Within this cohort, the mean LVEF was 28.0%, mean CAF was 10.7% and median CD3 CONCLUSIONS: Having both biopsy-proven higher myocardial inflammation and greater fibrosis predicted the worst clinical prognosis in patients with DCM.