title: Low prevalence of heparin-induced thrombocytopenia after cardiac surgery in Thai patients.
abstract: BACKGROUND
  Heparin induced-thrombocytopenia (HIT) has been well recognized in Western countries. However, there are no data in the Thai population. We therefore investigated the prevalence of anti-platelet factor 4 (PF4)/heparin antibodies, HIT, and its thrombotic complications in Thai patients undergoing cardiac surgery using unfractionated heparin.
  
  
  METHODS
  Seventy-three consecutive patients were prospectively enrolled in this study. Blood samples before operation and week 1, week 2, and week 3 after operation were collected from each patient for HIT antibody screening by enzyme-linked immunosorbent assay using IgG antibody specific to the PF4/heparin complex. Positive samples were further analyzed by (14)C-serotonin release assay. Complete blood count was performed daily during the first week, then weekly for 3 weeks.
  
  
  RESULTS
  No patient had detectable anti-PF4/heparin antibodies at baseline. Five patients sero-converted during the course of the study for anti-PF4/heparin IgG: 3 (4.1%) at week 1, 4 (5.5%) at week 2, and 5 (6.8%) at week 3 after surgery. However, none of these patients had anti-PF4/heparin antibodies that resulted in (14)C-serotonin release to be considered clinically significant antibodies. Post-operative thrombocytopenia after the operation was found in 35 patients (47.9%), but was not considered to be caused by HIT. Thromboembolic events occurred in 3 patients (4.1%) during follow up; however, none of these patients had positive PF4/heparin antibody tests.
  
  
  CONCLUSIONS
  Our study represents the first study to examine Thai patients exposed to heparin in the context of cardiac surgery. We found a lower prevalence of positive anti-PF4/heparin antibodies and clinical HIT than previously published studies.
authors.affiliation: Division of Hematology, Department of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Kochawan
authors.initials: K
authors.lastname: Boonyawat
authors.affiliation: Division of Hematology, Department of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. Electronic address: pantep.ang@mahidol.ac.th.
authors.forename: Pantep
authors.initials: P
authors.lastname: Angchaisuksiri
authors.affiliation: Division of Hematology, Department of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Katcharin
authors.initials: K
authors.lastname: Aryurachai
authors.affiliation: Department of Surgery, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Suchart
authors.initials: S
authors.lastname: Chaiyaroj
authors.affiliation: Department of Hematology, St. George Hospital, Kogarah, NSW, Australia.
authors.forename: Zohra
authors.initials: Z
authors.lastname: Ahmadi
authors.affiliation: Department of Hematology, St. George Hospital, Kogarah, NSW, Australia.
authors.forename: Beng Hock
authors.initials: BH
authors.lastname: Chong
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects* / Q000276:immunology; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D005260:Female; D006493:Heparin / Q000009:adverse effects* / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010978:Platelet Factor 4 / Q000276:immunology; D015995:Prevalence; D013785:Thailand / Q000453:epidemiology; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced* / Q000453:epidemiology*
chemical_list: D000925:Anticoagulants; D007074:Immunoglobulin G; D010978:Platelet Factor 4; D006493:Heparin
keywords: Cardiac surgery; Heparin; Thai; Thrombocytopenia; Thrombosis