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.

Commentary: Are platelet patterns repeated in delayed heparin-induced thrombocytopenia/heparin-induced thrombocytopenia and thrombosis syndrome after cardiac surgery?

“…Evaluation of this case series of Catalano and colleagues emphasizes that a thrombotic postoperative event is a potential indicator for HITTS during readmission even in the absence of thrombocytopenia. 3 Furthermore, provoking these patients with heparin worsens the situation, as demonstrated in this case series, in which the thrombocytopenia (and likely the thrombosis) was exacerbated by the administration of heparin. Alternative anticoagulants to heparin should be used pending a more definitive diagnosis.…”

“… 2 Awareness of this phenomenon in postoperative cardiac surgery patients is heightened by the case series reported by Catalano and colleagues in this issue of the Journal . 3 Their retrospective analysis spanned 28 months at a busy cardiac surgery center and included 2496 patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). During that time, 351 patients (14%) were readmitted within 30 days, 6 of whom (1.7%) were diagnosed with HIT confirmed by both positive heparin-PF4 antibodies (on enzyme-linked immunosorbent assay) and a positive serotonin release assay.…”

Non-heparin-induced thrombocytopenia in patients after open-heart surgery

“…HIT is rarely observed in patients in the ICU (0.5-1%); Catalona et al reported a rate of only 0.2% (6/2483) of patients after open-heart surgery. 4,18 Therefore, it is necessary to consider other factors that may more frequently lead to the development of thrombocytopenia. In logistic regression analysis, we found that age ≥80 years increased the risk of developing moderate-severe thrombocytopenia ninefold compared with age 18-39 years.…”

Commentary: Getting HIT with HIT minus T (thrombosis without thrombocytopenia)

“…Heparin-induced thrombocytopenia suggests the obligatory association of absolute or relative thrombocytopenia, yet, as shown by Catalano and coworkers, 3 HIT may still be present without thrombocytopenia. In 5 of 6 patients readmitted for thromboembolism after cardiopulmonary bypass, readmission platelet counts were not significantly different from the preoperative values.…”