Cardiac involvement in autoimmune myositis and mixed connective tissue disease.

The clinical cardiac manifestations most frequently reported in idiopathic inflammatory myopathies, myositis, are congestive heart failure, conduction abnormalities, that may lead to complete heart block and coronary artery disease. Although clinically overt cardiac involvement is rarely reported in myositis patients, subclinical manifestations are frequently observed and are predominated by conduction abnormalities and arrhythmias detected by ECG. Furthermore, cardiovascular manifestations constitute a major cause of death in myositis, thus cardiac involvement maybe overlooked in these patients. Also children with juvenile dermatomyositis may develop cardiac involvement although the frequency seems to be low. The underlying pathophysiologic mechanisms that may cause cardiac manifestations could involve myocarditis and coronary artery disease as well as involvement of the small vessels of the myocardium. In patients with mixed connective tissue disease (MCTD) clinically significant cardiac involvement is also rare, the most frequently reported manifestations being pericarditis and pulmonary hypertension, the latter often attributable to small vessel disease, and often a prognostic unfavourable manifestation.