FACTOR-V-LEIDEN AND THROMBOTIC COMPLICATIONS IN HEPARIN-INDUCED THROMBOCYTOPENIA

To determine whether factor V Leiden is associated with thrombotic eve nts in patients with heparin-induced thrombocytopenia (HIT), we evalua ted 165 patients with serologically confirmed HIT for the presence of factor V Leiden and determined the incidence of venous or arterial thr ombosis during the period of HIT. Factor V Leiden was detected in 16 o f 165 HIT patients (9.7%). HIT-associated venous thrombosis occurred i n 11 of 16 factor V Leiden positive subjects and 94 of 149 factor V Le iden negative subjects (69% vs. 63%; p = 0.79). Arterial thrombosis oc curred in 1 of 16 factor V Leiden positive subjects and 21 of 149 fact or V Leiden negative subjects (6% vs. 14%; p = 0.70). There was no dif ference in the incidence of proximal limb DVT, pulmonary embolism, ven ous limb gangrene, local skin reactions, hemorrhagic adrenal infarctio n, stroke, or myocardial infarction between the groups. No difference in the severity of venous thrombosis between Leiden positive and negat ive subjects was detected. Our data suggest that in the acute prothrom botic milieu of HIT, heterozygous factor V Leiden is not an important additional risk factor for thrombosis.