The occurrence of cardiac manifestations and their relationship with the lupus anticoagulant (LA) in SLE was studied in 74 patients who were followed up for 22 years (median), of which 16 years were after the initial LA testing. Pericarditis was the most common cardiac event occurring in 16 (22%) patients but it did not correlate with LA. Valvular heart disease, coronary artery disease, left ventricular failure and/or cor pulmonale were observed in 16 (22%) patients. Taken together, their occurrence was associated with a history of leg ulcers (odds 3.8, P = 0.028) but not with LA or other common clinical manifestations of the antiphospholipid syndrome. Valvular heart disease in five patients was significantly associated with LA (P = 0.05). Cor pulmonale due to chronic pulmonary embolism was present in two patients with LA. Myocardial infarctions in five patients occurred late in the course of disease but in relatively young patients (mean 43 years). Fatal myocardial infarction in the absence of atherosclerosis in two LA-positive patients supports a pathogenetic role for LA in these cases. In conclusion, of the various cardiac complications in SLE, valvular heart disease and cor pulmonale appear to be connected with the antiphospholipid syndrome. Both conditions should be actively sought in patients with LA to decrease possible adverse events (arterial emboli and right ventricular failure) affecting the patients' prognosis.