Heparin-induced thrombocytopenia: a serious complication of heparin therapy for acute stroke

Despite the lack of supporting evidence, unfractionated heparin (UFH) is frequently given to acute ischemic stroke patients. This study was designed to determine the incidence of heparin-induced thrombocytopenia (HIT) during acute stroke and to elucidate the clinical features of stroke patients with HIT.

Of 1,078 consecutive patients with acute ischemic stroke, 392 were given intravenous UFH. Ten of these developed prominent thrombocytopenia without any other underlying etiology; they were suspected of having HIT. These 10 patients were studied retrospectively. The clinical diagnosis of HIT was made according to two published scoring systems. Antiplatelet factor 4/heparin antibodies in the plasma were detected by the enzyme-linked immunosorbent assay (ELISA) and were confirmed by the 14C-serotonin release assay.

Eight patients met the criteria for clinical HIT according to both scoring systems. Of these, serological tests were positive in 2 patients only on ELISA and in 2 patients on both assays. The amount of UFH given was greater in the 4 patients with positive serological findings than in the others (p = 0.043). Three patients developed further thromboembolic events, including 1 patient who developed possible cancer-associated thrombosis. Two patients were dead and the remaining 6 patients were dependent at the time of hospital discharge. The clinical severity and outcome of these patients were relatively unfavorable compared to other acute patients.

The prevalence of HIT was 0.5% based on both the clinical scoring systems and serological assays. Monitoring for HIT should be included in the medical management of stroke to avoid further complications.