Antithrombin-III deficiency in ischemic stroke.

To the Editor Hereditary antithrombin III (AT-III) deficiency is associated with an increased risk for venous thrombosis and pulmonary embolism and possibly also for arterial embolism,including cerebral thromboembolism. Acquired AT-III deficiency is more common, but its pathogenetic and clinical relevance is unclear. We present here three patients with acquired AT-III deficiency as a possible risk factor for ischemic stroke. Blood samples were drawn within 24 hours after stroke onset in 45 consecutive patients (24 men and 21 women) with cerebral infarction (/i=38) or transient ischemic attack (TTA) (n=l). Mean age was 62±10 (range 36-83) years. Antithrombin m activity was measured with Coatest Antithrombin (Kabi, Stockholm, Sweden) in the automated coagulation laboratory instrument. Reference values were established in 84 healthy blood donors (85-120%). The mean AT-III level was not significantly decreased in patients with cerebral infarction (98±19%) or TIA (97±12%) as compared with the control group (102±9%) (mean±SD). However, three patients with cerebral infarction had AT-III levels lower than 3 SDs from the mean of the control group. The first patient (AT-III 57%), a 43-year-old previously healthy woman, developed a cerebral infarction in the territory of the right median cerebral artery and, simultaneously, an arterial embolus in her right brachial artery. She smoked 30 cigarettes daily and was on temporary medication of Gestagen (norethisteron. acet., 10 mg/day). The second patient (AT-III 60%) was a 68-year-old woman with type II diabetes mellitus who had iterated venous thromboses for 12 years and three earlier brain infarctions despite medication with 250 mg acetylsalicylic acid daily. The third patient (AT-III 62%) was a previously healthy 65-year-old man who had a cerebral infarction in the territory of the left median carotid artery 3 days after operation for a prostatic neoplasm. None of the patients had a family history of vascular disease or thrombosis, and blood tests, electrocardiogram, and ultrasonic duplex scanning of the carotid arteries were normal in all three patients. Antithrombin III levels were normal in all patients after 6-18 months.