Cardiomyopathic syndrome caused by coronary artery disease. III: Prospective clinicopathological study of its prevalence among patients with clinically unexplained chronic heart failure.

Each day, for one year, the medical records of adult patients who died in hospital were reviewed before seeing the necropsy findings. For those patients who had had chronic left or left and right heart failure, a presumptive cause was assigned on the basis of antemortem clinical data. Of 740 consecutive patients who were studied at necropsy, 90 had had chronic heart failure. In 15 patients the cause of heart failure was not apparent by clinical criteria; of these, 7 were found at necropsy to have cardiomyopathic syndrome caused by coronary artery disease. In retrospect, the presence of overt diabetes mellitus was a clue that cardiomyopathy caused by coronary artery disease was the cause of clinically unexplained heart failure; 5 of 7 patients with unexplained heart failure who were found to have this at necropsy were diabetic, whereas only 1 of the other 8 patients with clinically unexplained heart failure was diabetic (P less than 0.05). Patients in whom clinically unexplained heart failure was found to be the result of cardiomyopathy caused by coronary artery disease had multiple myocardial infarctions on pathological examination, which, with one exception, were nontransmural. By contrast, myocardial infarctions were transmural on pathological examination in each of 7 matched 'controls' with heart failure, in whom the diagnosis of coronary artery disease had been clinically apparent (P less than 0.01).