Suspected heparin-induced thrombocytopaenia in pulmonary thromboendarterectomy: retrospective cohort

Abstract

Objectives: Heparin is given for anticoagulation during and after pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension. Our objective was to add to the limited data available on the incidence, management and outcomes of suspected heparin-induced thrombocytopaenia after pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension.

Methods: This retrospective single-centre study included consecutive patients with suspected heparin-induced thrombocytopaenia after pulmonary thromboendarterectomy done in 2005-2018. Confirmed heparin-induced thrombocytopaenia was defined as positive findings from both the antibody test and the platelet aggregation test. Patients with versus without confirmed heparin-induced thrombocytopaenia were compared, as well as patients with versus without heparin replacement therapy within the group with unconfirmed heparin-induced thrombocytopaenia. The platelet counts over time were compared to those in controls without suspected heparin-induced thrombocytopaenia.

Results: Heparin-induced thrombocytopaenia was suspected in 86 (6.3%) of 1360 patients and confirmed in 16 (16/86, 19%), all of whom received heparin replacement therapy and survived to intensive care unit discharge. Of the remaining 70 patients, 28 (40%) received heparin replacement therapy and less often experienced bleeding compared to the other 42 (3.6% vs 21.4%, P = 0.043). Intensive care unit mortality was 17/70 (24.3%) and was lower in the subgroup given heparin replacement therapy (10.7% vs 33.3%; P = 0.046). Confirmed heparin-induced thrombocytopaenia was associated with a sharp platelet-count drop on Day 5. In unconfirmed suspected heparin-induced thrombocytopaenia, the early platelet-count decline was similar to that in the controls without suspected heparin-induced thrombocytopaenia, but the baseline count was lower.

Conclusions: Clinical features suggesting heparin-induced thrombocytopaenia after pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension were associated with excess mortality. Relay heparin replacement therapy was associated with lower mortality and fewer bleeding events.

Keywords: chronic thromboembolic pulmonary hypertension; heparin-induced thrombocytopaenia; pulmonary thromboendarterectomy.

Graphical abstract

Figure 1:

Patient flow chart. CTEPH: chronic thromboembolic pulmonary hypertension; ELISA: enzyme-linked immunosorbent assay to detect heparin-platelet-4 factor antibodies; HIT: heparin-induced thrombocytopenia; PAT: platelet aggregation test; PTE: pulmonary thromboendarterectomy. *Test not done for 35 patients: 22 score 4T<4, 13 score 4T 4-5 (7 with alternative diagnosis and 6 with thrombocytopenia >50 10⁹/l)

Figure 2:

Platelet counts over the first 15 days after surgery in the groups with suspected and confirmed heparin-induced thrombocytopaenia (HIT), suspected but unconfirmed HIT and no suspicion of HIT