Cardiac involvement in progressive systemic sclerosis and polymyositis: a comparative study in 116 patients.

: A comparative study was carried out in 116 patients-51 with progressive systemic sclerosis (PSS) and 65 with polymyositis (PM) to detect the cardiac involvements secondary to these two collagen diseases. Different forms of cardiac involvement could be detected in 51% of the patients with PSS and in 18.5% of those with PM. The most frequent cardiac dysfunctions were disturbances of rhythm and conduction probably due to the coronary vascular changes in PSS and to processes of fibrosis and degenerescence of the specific myocardial fibers in PM. Myocardial lesions expressed by myocarditis and cardiomyopathies are not infrequent and have important prognostic implications. In the group of patients studied the valvular cardiopathies and clinically evident pericardites were rare. Cardiac involvement clearly proved more frequent in PSS - in which the pathogenic mechanism is mainly vascular - than in PM. This emphasizes the great importance of coronary circulation disturbances in the pathogenesis of collagen heart diseases.