Pulmonary and cardiac manifestations of polymyositis-dermatomyositis.

Polymyositis-dermatomyositis (PM-DM) is an inflammatory disease of muscle and skin mediated by autoimmune and cellular events. Most typically, muscle weakness is the usual presentation. This review emphasizes that often the systemic components of this disease may mask the usual presentation and actually may be the presenting and only manifestations; more often than not they are the causes of increased morbidity and mortality. In particular, the cardiopulmonary manifestations may dominate the disease course. Cardiac complications include congestive heart failure resulting from a primary cardiomyopathy, disrhythmias and atrioventricular conduction disturbances, sick sinus syndrome, and cor pulmonale either secondary to interstitial lung disease (ILD) or primary pulmonary artery hypertension. Recurrent aspiration pneumonia results from pharyngeal muscle involvement by the myositic process. Several histologic patterns of ILD can emerge with varying outcomes and responses to immunosuppresive therapy. Involvement of the muscles of respiration can lead to hypercapnic respiratory failure, diaphragmatic dysfunction, hypostatic pneumonia, and restrictive lung disease.