Procainamide-induced circulating anticoagulants in a congenitally-deficient factor XI patient.

A 70 year old male patient admitted for coronary bypass surgery presented with a procainamide-induced lupus syndrome. This syndrome included a LLAC with a positive IgM ACA titer as well as a factor XII inhibitor. These drug-induced inhibitors were superimposed upon the patient's congenital deficiency of factor XI. The methods used to identify these abnormalities are described together with the replacement therapy employed to cover the surgical procedure. The long-term withdrawal of procainamide was associated with correction of all coagulation abnormalities except the factor XI deficiency.