Heparin-induced thrombocytopenia in patients readmitted after open cardiac surgical procedures: A case series

Abstract

Objectives: Heparin-induced thrombocytopenia (HIT) is an immune-mediated complication that occurs in a small percentage of patients exposed to heparin. Concerns of HIT are particularly high in patients undergoing cardiac procedures requiring cardiopulmonary bypass, as they are exposed to high doses of heparin intraoperatively. Our aim was to identify and assess the hospital courses of patients who were diagnosed with HIT during readmission following cardiac surgery.

Methods: A retrospective review of patients who underwent open cardiac surgical procedures from June 2017 through October 2019 was performed. Of these, we identified patients who were newly diagnosed with HIT upon readmission. HIT positivity was defined as a positive anti-PF4 antibody screening test, plus a positive serotonin release assay.

Results: Of the 2496 patients identified, 13 patients were HIT positive on index admission and were excluded. Of the remaining 2483 patients, 351 were readmitted within 30 days. Six were newly diagnosed with HIT during readmission, 5 of whom presented with thrombotic complications. One patient was readmitted with thrombocytopenia and was started on argatroban; the remaining 5 did not have a significantly lower platelet count on readmission. Of the 12 patients readmitted for venous thromboembolism, 4 tested positive for HIT.

Conclusions: HIT can have a delayed appearance following open heart surgery. Venous thromboembolism appears to be a significant indicator for HIT during readmission, even in the absence of thrombocytopenia. This may support the use of non-heparin anticoagulation for cardiac surgery patients readmitted with thromboembolism until HIT status is determined.

Keywords: CPB, cardiopulmonary bypass; DVT, deep-vein thrombosis; ELISA, enzyme-linked immunosorbent assay; HIT; HIT, heparin-induced thrombocytopenia; HITT, heparin-induced thrombocytopenia and thrombosis; PE, pulmonary embolus; PF4, platelet factor 4; UFH, unfractionated heparin; VTE, venous thromboembolism; cardiac surgery; thrombotic complications.

Graphical abstract

Composite platelet trends, index admission, and readmission.

Figure 1

Overview of patient selection, platelet count trends, and conclusions of our analysis of patients diagnosed with heparin-induced thrombocytopenia and thrombosis during readmission. The mean preoperative platelet count was 183.0 ± 58.4 K/μL, which recovered, on average, to 91.8% of preoperative levels by discharge. These patients presented upon readmission with a mean platelet count of 169 K/μL, not significantly lower than their discharge platelet count. However, following heparin product administration, there was a rapid and severe reduction in platelet count to a mean of 41 K/μL. HIT, Heparin-induced thrombocytopenia.

Figure 2

Depiction of index hospital admission and readmission course, anticoagulation administration, and trending platelet counts of 6 cardiac surgical patients readmitted with HIT. The readmission platelet trends highlight that patients 2-6 presented on readmission with thrombosis without significant thrombocytopenia; the subsequent anticoagulation with heparin products led to rapid reductions in platelet counts and HIT diagnosis. HIT, Heparin-induced thrombocytopenia; SQH, subcutaneous heparin; IV, intravenous.