Heart disease is the main cause of death in patients with Takayasu arteritis. It has been reported that this disease is closely related to the presence of HLA Bw52 antigen. To assess the correlation between this antigen and left ventricular involvement, we studied 40 patients with Takayasu arteritis, 21 with and 19 without Bw52, using Tl-201 stress myocardial scintigraphy and echocardiography. Those with Bw52 had a significantly higher incidence of abnormal electrocardiographic findings (67% vs 26%; P < 0.05) and of aortic regurgitation (52% vs 11%; P < 0.05). The echocardiographically determined interventricular septal wall thickness plus left ventricular posterior wall thickness (25 +/- 8 vs 17 +/- 3 mm; P < 0.01) and the left ventricular mass (257 +/- 132 vs 142 +/- 51 g; P < 0.01) were significantly increased in the patients with Bw52. Scintigraphically determined perfusion abnormalities were significantly more frequent in those with Bw52 (76% vs 32%; P < 0.05). These observations indicate that patients with Takayasu arteritis and Bw52 antigen have a more severe left ventricular involvement than the patients without that antigen. The left ventricular impairment may account for the poor prognosis of Takayasu patients with Bw52.