HIGH PREVALENCE OF ANTIPHOSPHOLIPID ANTIBODIES IN PATIENTS TAKING PROCAINAMIDE

8Objective, To determine whether antiphospholipid antibodies (aPL) are more prevalent in cardiac patients taking procainamide than in a cont rol population of similar elderly cardiac patients and to determine wh ether these antibodies react in an ELISA in which the primary antigen is beta(2)-glycoprotein I (beta(2)-GPI). Methods, aPL and antibodies t o beta(2)-GPI were measured in 66 patients taking procainamide from a Veterans Administration Medical Center population and a control group of 30 similar cardiac patients not taking procainamide. Results, 21% o f the patients taking procainamide and no control patients were found to have moderate to high aPL. There were similar results in an assay t hat measured anti-beta(2)-GPI in the absence of exogenous phospholipid s. aPL were associated with antinuclear antibodies and antihistone ant ibodies but not with diabetes or clinical manifestations of drug relat ed lupus. There was no increase in cholesterol or past thrombotic hist ory associated with aPL, but there was a frequent history of noncardia c thrombosis in patients taking procainamide (25.7%). Conclusion. The predictive significance of procainamide induced aPL remains unknown bu t beta(2)-GPI dependent aPL may be of some concern in this elderly pop ulation already at high risk for thrombosis.