Cardiac calcific deposits in patients with primary hyperparathyroidism: preliminary results of a prospective echocardiographic study. To explain the incidence and significance of mitral and aortic valve calcification and calcific deposits in the myocardium, a prospective echocardiographic study was performed with 21 consecutive patients who had primary hyperparathyroidism (PHP) and with 21 age- and sex-matched control subjects with normocalcemia. Calcific deposits in the myocardium were seen in 13 patients (62%) with PHP, mainly in the interventicular septum, and in one control subject. Aortic valve calcification was observed in 12 patients (57%) with PHP and in one control subject. Calcification of the mitral valve was found in seven patients with PHP (33%) and three controls (14%). Calcification led to mild or moderate stenosis of the aortic valve in three patients with PHP and of the mitral valve in two patients with PHP. No stenosis was found in the subjects in the control group. Both calcification of the aortic and mitral valves and calcific deposits in the myocardium are common in patients with PHP and can be detected noninvasively by echocardiography. Because of the potential relationship of elevated calcium, calcification, and valvular heart disease, clinical evaluation of PHP should include echocardiographic studies before surgery is performed and during follow-up examination. 