AN ANALYTICAL COMPARISON OF COBALT CARDIOMYOPATHY AND IDIOPATHIC DILATED CARDIOMYOPATHY

Toxic cardiomyopathy (TC) has a rapid clinical course and morphologica lly resembles idiopathic dilated cardiomyopathy (IDC). To further char acterize TC, we used light microscopy to compare lesions caused by cob alt (Go) to those of IDC. Cobalt levels were also measured as a chemic al marker to differentiate TC from IDC. We reviewed cases with TC and IDC and excluded all cases with chemotherapy-induced myopathy and cate cholamine toxicity as well as cases with possible infectious, ischemic , or hypersensitivity-induced myopathies. We compared the light micros copic findings of 12 TC cases to 12 cases of IDC, and measured trace C o levels on digested heart tissue samples. The TC cases had prominent myofibrillar loss and atrophy; no cases had neutrophil infiltration or frank myocyte necrosis. In contrast, IDC had minimal myofibril loss a nd atrophy. Cobalt levels in the range of 0.6 to 5.45 mu g/g of dry ti ssue were obtained for the TC cases, while IDC demonstrated Co levels of 0.01-0.2 mu g/g. Distinction between TC and IDC is predominantly a function of myocyte change, with TC showing myofibrillar loss and atro phy in the absence of inflammatory infiltrates and fibrosis; IDC is pr edominantly associated with myocyte hypertrophy, atrophy, and fibrosis .