Myeloma of the heart.

There are a number of recognized causes of digoxinresistant atrial fibrillation, one of which is infiltration of the heart by malignant tumour. Extraosseous deposits of myeloma can be found in about 70 per cent of cases by careful necropsy (Hayes, Bennett, and Heck, I952; Churg and Gordon, 1950), the liver, spleen, and lymph nodes being by far the commonest sites. Cardiac involvement at necropsy is particularly uncommon. When it occurs it may predominantly involve either the pericardium (Goldberg and Mori, I970; Derechin, Goldberg, and Herron, I970) or the myocardium (Morse, ia920; Piney and Riach, 193I; Carlisle, I938). Clinically detectable extraosseous deposits during life seem to be particularly associated with IgD (Hobbs and Corbett, I969) and IgA (Edwards and Zawadzki, I967) myelomas. They are, however, rare, and indeed significant clinical manifestations due to myelomatous cardiac deposits were not reported until I970, when 2 cases of cardiac tamponade were described (Goldberg and Mori, I970; Derechin et al., I970). A case of IgA myeloma is presented in which digoxin-resistant atrial fibrillation, due to a deposit of myeloma involving the sinoatrial node, posed a major therapeutic problem. This is a previously undescribed manifestation of cardiac myeloma.