Underlying causes and long-term survival in patients with initially unexplained cardiomyopathy.

Background: Previous studies of the prognosis of patients with heart failur e due to cardiomyopathy categorized patients according to whether they had ischemic or nonischemic disease. The prognostic value of identifying more s pecific underlying causes of cardiomyopathy is unknown. Methods: We evaluated the outcomes of 1230 patients with cardiomyopathy. Th e patients were grouped into the following categories according to underlyi ng cause: idiopathic cardiomyopathy (616 patients); peripartum cardiomyopat hy (51); and cardiomyopathy due to myocarditis (111), ischemic heart diseas e (91), infiltrative myocardial disease (59), hypertension (49), human immu nodeficiency virus (HIV) infection (45), connective-tissue disease (39), su bstance abuse (37), therapy with doxorubicin (15), and other causes (117). Cox proportional-hazards analysis was used to assess the association betwee n the underlying cause of cardiomyopathy and survival. Results: During a mean follow-up of 4.4 years, 417 patients died and 57 und erwent cardiac transplantation. As compared with the patients with idiopath ic cardiomyopathy, the patients with peripartum cardiomyopathy had better s urvival (adjusted hazard ratio for death, 0.31; 95 percent confidence inter val, 0.09 to 0.98), and survival was significantly worse among the patients with cardiomyopathy due to infiltrative myocardial disease (adjusted hazar d ratio, 4.40; 95 percent confidence interval, 3.04 to 6.39), HIV infection (adjusted hazard ratio, 5.86; 95 percent confidence interval, 3.92 to 8.77 ), therapy with doxorubicin (adjusted hazard ratio, 3.46; 95 percent confid ence interval, 1.67 to 7.18), and ischemic heart disease (adjusted hazard r atio, 1.52; 95 percent confidence interval, 1.07 to 2.17). Conclusions: The underlying cause of heart failure has prognostic value in patients with unexplained cardiomyopathy. Patients with peripartum cardiomy opathy appear to have a better prognosis than those with other forms of car diomyopathy. Patients with cardiomyopathy due to infiltrative myocardial di seases, HIV infection, or doxorubicin therapy have an especially poor progn osis. (N Engl J Med 2000;342:1077-84.) (C) 2000, Massachusetts Medical Soci ety.