Prospective multicentre cohort study of heparin‐induced thrombocytopenia in acute ischaemic stroke patients

Summary Acute ischaemic stroke patients sometimes receive heparin for treatment and/or prophylaxis of thromboembolic complications. This study was designed to elucidate the incidence and clinical features of heparin‐induced thrombocytopenia (HIT) in acute stroke patients treated with heparin. We conducted a prospective multicentre cohort study of 267 patients who were admitted to three stroke centres within 7 d after stroke onset. We examined clinical data until discharge and collected blood samples on days 1 and 14 of hospitalization to test anti‐platelet factor 4/heparin antibodies (anti‐PF4/H Abs) using an enzyme‐linked immunosorbent assay (ELISA); platelet‐activating antibodies were identified by serotonin‐release assay (SRA). Patients with a 4Ts score ≥4 points, positive‐ELISA, and positive‐SRA were diagnosed as definite HIT. Heparin was administered to 172 patients (64·4%: heparin group). Anti‐PF4/H Abs were detected by ELISA in 22 cases (12·8%) in the heparin group. Seven patients had 4Ts ≥ 4 points. Among them, three patients (1·7% overall) were also positive by both ELISA and SRA. National Institutes of Health Stroke Scale score on admission was high (range, 16–23) and in‐hospital mortality was very high (66·7%) in definite HIT patients. In this study, the incidence of definite HIT in acute ischaemic stroke patients treated with heparin was 1·7% (95% confidence interval: 0·4–5·0). The clinical severity and outcome of definite HIT were unfavourable.