Journal of Blood Disorders & Transfusion

Abstract

Low Incidence of Clinically Significant Heparin Induced Thrombocytopenia after Cardiopulmonary Bypass Surgery

Abhinav B Chandra, Navneet Mittal, Shilpa Sambidi, Anuradha Belur, Swati Pathak, Himanshu Pathak and Yiqing Xu

Introduction: Thrombocytopenia after cardiopulmonary bypass (CPB) is common, and the diagnosis of heparin induced thrombocytopenia (HIT) remains a challenge in clinical practice despite the guidance from the “4T” diagnostic scoring criteria and the laboratory tests. Objectives: This study aims to evaluate (i) the temporal laboratory characteristics of thrombocytopenia after CPB and (ii) the incidence of clinically significant HIT based on clinical assessment. Methods: A retrospective data review of patients undergoing coronary artery bypass graft surgery or valve surgery who were also placed on bypass pump and received intra-operative heparin. Results: Among 450 study patients, 142 (31.5%) patients developed decrease of platelet counts at least 33% below base line following surgery, with a median degree of 61%. The initial platelet nadir occurred between day 0 to day 4 (median 1 day). The cumulative percentage of patients demonstrating recovery of their platelet count was 44% by day 4, 80% by day 5 and 100% by day 10. Only 9 patients (2%) showed a second decrease in platelet count. By clinical assessment, including clinical outcome, platelet recovery, Doppler test results and the need for use of direct thrombin inhibitors, not a single case of clinically significant HIT was diagnosed. Heparin associated platelet factor 4 (H-PF4) antibody test was positive in 10% and 0% of patients who developed platelet count decrease in the first and second phase, respectively. Conclusion: A very low incidence of clinically significant HIT after CABG using clinical assessment was observed and further prospective trials are warranted to confirm this observation.