Eosinophilia and myocardial ischemia secondary to polyarteritis. A discussion of pathogenesis on the basis of a case history.

The importance of eosinophilia in patients with severe polyarteritis causing myocardial ischaemia is discussed in connection with a case history. A 20 year old man complaining of recurrent episodes of dyspnoea was found to have a very high eosinophil count, and no allergy as assessed by prick test, RAST and histamine liberation test. The eosinophilia responded to steroid treatment. The patient died 2 years later, at which time his eosinophilia had recurred, of heart failure, with pericardial and pleural effusions and a congested liver. Post-mortem examination showed severe ischaemic changes in the myocardium and chronic inflammatory changes in the small branches of the coronary arteries. The pathologic diagnosis was polyarteritis (in some degree of remission) confined to the heart. Since the clinical and electrocardiographic diagnosis of myocardial ischaemia and cardiomyopathy in patients with polyarteritis and/or eosinophilia can be difficult, other non-invasive investigations are indicated when there is a suspicion that the heart may be affected. Echocardiography, and possibly endomyocardial biopsy may be used at an early stage to assess the response to immunosuppressive treatment. Prophylactic treatment of any associated clotting disorder should be considered. The aetiology and pathogenesis of polyarteritis is unknown, but endothelial damage caused by eosinophilia early in the disease process may be important. Adequate treatment should therefore be given in order to reduce the eosinophil count and a close follow-up is essential in order to diagnose a relapse of the eosinophilia early and thereby possibly prevent fatal cardiac complications.