OBJECTIVE Current knowledge of the cardiac manifestations of rheumatoid arthritis (RA) stems only from clinical and transthoracic echocardiography (TTE) studies. To determine the incidence and type of heart lesions in RA, we coupled TTE with transesophageal echocardiography (TEE), which is more sensitive and more accurate. METHODS Thirty unselected RA patients (26 women and 4 men aged 27 to 84 years, with a mean age of 57.8+/-15.1 years) free of known progressive heart disease underwent a chest radiograph, an electrocardiogram, laboratory tests, and TTE coupled with TEE. Results were compared with those in age- and sex-matched patients who were free of rheumatic disease and who underwent TEE to investigate a neurologic or cardiologic disorder. RESULTS Mitral regurgitation (MR) was evidenced in 24 cases (80%). Among the controls, only 11 (37%) had MR (P < 0.001). Aortic regurgitation was found in 10 cases (33%), versus 7 controls (not significant-NS). Seven cases (23%) versus only 2 controls (7%) had tricuspid valve abnormalities (NS). Pericarditis was found in 4 cases (13%) and in none of the controls. Eleven cases had evidence of cardiomyopathy (37%) and 12 (40%) had atheroma of the aorta, this last being missed by TTE in 10 patients. Echo-generating nodules were seen on a mitral valve in 2 cases and on an aortic valve in 1. We found no correlations linking cardiac lesions to clinical or laboratory features of RA. CONCLUSIONS Our study demonstrated that cardiac involvement, particularly of the mitral valve, is extremely common in RA patients.