Allograft pathology in patients transplanted for idiopathic dilated cardiomyopathy.

There are few morphologic studies on idiopathic dilated cardiomyopathy (CM) treated with transplant. We prospectively correlated gross, histologic, and clinical findings pertaining to hearts explanted in a 5-year period from patients with a clinical diagnosis of nonischemic CM and also correlated left ventricular diameter with preoperative echocardiographic reports. Of 64 patients with a clinical diagnosis of dilated cardiomyopathy (DC), 42 were men (age, 51 ± 13 y) and 22 were women (age, 42 ± 18 y). The pathologic diagnosis was idiopathic (dilated) cardiomyopathy (DC) in 55 patients (86%) and features of specific CM in 9 patients (14%). Specific diagnoses were fibrofatty change consistent with arrhythmogenic right ventricular cardiomyopathy (n=6), amyloidosis (n=2), and sarcoidosis (n=1), none of which were suspected clinically. The 55 hearts with idiopathic DC had a mean heart weight of 508 (range, 220 to 980) g. Pathologic subsets of the DC group included 4 hearts without enlargement, cavity dilatation, or significant histologic findings (minimal DC); 3 hearts with histologic evidence of healed myocarditis; and 5 hearts with mildly noncompacted left ventricle with hypertrabeculation. Five patients had prior mitral or tricuspid valve replacement/repairs to manage heart failure. There were 7 postpartum DC cases, 1 with a histologic pattern of healed myocarditis and 1 alcoholism-associated DC. Familial DC comprised 16% (9 of 55) of patients. In patients without prior assist device placement, pathologic left ventricular cavity diameter correlated with echocardiographic end-diastolic volume (r , 0.8, P<0.0001). Morphologically, DC is a heterogeneous group. Areas of fibrofatty change and features of noncompaction are not uncommon. Left ventricular measurement at explant correlates well with echocardiographic findings, with a relatively consistent underestimation of the diameter.