E-page Original Images: Slowly progressive conduction system disturbance in a patient with polymyositis

Polymyositis (PM) is an autoimmune disease characterized by progressive weakness of the proximal skeletal muscles that can affect the heart. Cardiac manifestations usually present with minimal symptoms and the most often reported include congestive heart failure as consequence of diffuse myocarditis, arrhythmias and conduction system disturbances that can be related to secondary vascular changes and cellular infiltration. Vascular alterations in the coronary arteries have also been reported such as vasculitis, intimal proliferation, media sclerosis and microvessel disease; that has been associated with vasospastic angina. Small vessel disease characterized by narrowing of vessel lumen by smooth muscle hyperplasia with little or no intimal proliferation was also observed. This may cause clinical symptoms like palpitations and angina pectoris. Electrocardiography (ECG) abnormalities included mainly left anterior fascicular block (LAFB) and right bundle branch block (RBBB). AV blocks have been reported less frequently. Autopsy studies revealed histopathological changes in the conducting system including lymphocytic infiltration, fibrosis of the sinoatrial node and contraction band necrosis. Some of these cases evolved into complete heart block.