eart transplantation has been used to treat dilated cardiomyopathy (DCM) in patients in whom medical therapy or a left ventricular assist device has failed. However, there are a limited number of hearts available for transplantation, and many patients die while awaiting transplantation. Recently, partial left ventriculectomy (PLV; the Batista procedure) 1-6 has received attention as an alternative or bridging treatment for severe cardiomyopathies. In this operation, the surgeon partially resects the left ventricle in an attempt to decrease left ventricular wall tension by reducing chamber volume. Therefore it is necessary to establish the indications for this procedure and to determine the prognosis following this surgery.Immunologic abnormalities, viral infections, and genetic predisposition are possible factors involved in the development of myocardial injury in DCM. 7 The presence of inflammatory cell infiltrates [8][9][10][11] and viral genomes [12][13][14][15] 16,17 It is therefore quite important to determine the role of inflammatory cell infiltrates or active myocarditis in the development of DCM.The histopathologic features of myocardial injury and the severity of cardiomyopathy are considered to be factors determining the prognosis following PLV. We previously reported that severe inflammatory cell infiltration might serve as a predictor of poor outcome, 18,19 but we could not determine a significant correlation between any histopathologic findings and the early prognosis of patients with DCM following PLV, because the number of patients was too small.The purpose of present study was to determine the involvement of active myocarditis in DCM using histopathologic, immunohistochemical and virologic studies of myocardial specimens obtained by PLV. In addition, this study aimed to determine the relationship between the histopathologic findings and the early prognosis of patients with DCM following PLV using more histopathologic factors in a larger number of cases compared with our previous study. 18,19 Jpn Circ J 2001; 65: 797 -802 (Received October 27, 2000; revised manuscript received May 28, 2001; accepted June 11, 2001 Yasuhiro Horii, MD*; Tadashi Isomura, MD*; Hisayoshi Suma, MD* Partial left ventriculectomy (PLV) can be used to treat refractory congestive heart failure caused by dilated cardiomyopathy (DCM). In order to understand the relationship between the underlying myocardial injury and early clinical outcomes after PLV, histopathologic, immunohistochemical and virologic studies of the resected myocardium were performed. The posterolateral left ventricular walls from 27 patients with idiopathic DCM were examined. Cardiomyocyte diameter, degree of myocardial fibrosis, degree of cardiomyocyte degeneration, and degree of inflammatory cell infiltration were compared with mortality rates. Polymerase chain reaction was performed to detect enterovirus genome in the myocardium. Some patients had inflammatory cell infiltrates with focal accumulations of lymphocytes and macrophages, including both cytot...