Cardiac Surgery Successfully Managed With Cangrelor in a Patient With Persistent Anti-PF4/Heparin Antibodies 8 Years After Heparin-Induced Thrombocytopenia

A Case Report of Pulmonary Embolectomy Under Cardiopulmonary Bypass in a Patient with Intracranial Hemorrhage and History of Heparin-Induced Thrombocytopenia

Pulmonary embolism is a common complication after intracranial hemorrhage. As thrombolysis is contraindicated in this situation, surgical pulmonary embolectomy may be indicated in case of high-risk pulmonary embolism but requires transient anticoagulation with heparin during cardiopulmonary bypass. We report the case of a patient with a history of heparin-induced thrombocytopenia who presented with a high-risk pulmonary embolism 10 days after the spontaneous onset of a voluminous intracerebral hematoma. Despite high doses of heparin required to run the cardiopulmonary bypass and subsequent anticoagulation by danaparoid sodium, the brain hematoma remained stable and the patient was discharged without complications 30 days after surgery.

Novel Knowledge about Molecular Mechanisms of Heparin-Induced Thrombocytopenia Type II and Treatment Targets

Heparin-induced thrombocytopenia type II (HIT II), as stated in the literature, occurs in about 3% of all patients and in 0.1-5% of surgical patients. Thrombosis develops in 20-64% of patients with HIT. The mortality rate in HIT II has not decreased using non-heparin treatment with anticoagulants such as argatroban and lepirudin. An improved understanding of the pathophysiology of HIT may help identify targeted therapies to prevent thrombosis without subjecting patients to the risk of intense anticoagulation. The review will summarize the current knowledge about the pathogenesis of HIT II, potential new therapeutic targets related to it, and new treatments being developed. HIT II pathogenesis involves multi-step immune-mediated pathways dependent on the ratio of PF4/heparin and platelet, monocyte, neutrophil, and endothelium activation. For years, only platelets were known to take part in HIT II development. A few years ago, specific receptors and signal-induced pathways in monocytes, neutrophils and endothelium were revealed. It had been shown that the cells that had become active realised different newly formed compounds (platelet-released TF, TNFα, NAP2, CXCL-7, ENA-78, platelet-derived microparticles; monocytes-TF-MPs; neutrophils-NETs), leading to additional cell activation and consequently thrombin generation, resulting in thrombosis. Knowledge about FcγIIa receptors on platelets, monocytes, neutrophils and FcγIIIa on endothelium, chemokine (CXCR-2), and PSGL-1 receptors on neutrophils could allow for the development of a new non-anticoagulant treatment for HIT II. IgG degradation, Syk kinase and NETosis inhibition are in the field of developing new treatment possibilities too. Accordingly, IdeS and DNases-related pathways should be investigated for better understanding of HIT pathogenesis and the possibilities of being the HIT II treatment targets.

How to Solve the Conundrum of Heparin-Induced Thrombocytopenia during Cardiopulmonary Bypass

Heparin-induced thrombocytopenia (HIT) is a major issue in cardiac surgery requiring cardiopulmonary bypass (CPB). HIT represents a severe adverse drug reaction after heparin administration. It consists of immune-mediated thrombocytopenia paradoxically leading to thrombotic events. Detection of antibodies against platelets factor 4/heparin (anti-PF4/H) and aggregation of platelets in the presence of heparin in functional in vitro tests confirm the diagnosis. Patients suffering from HIT and requiring cardiac surgery are at high risk of lethal complications and present specific challenges. Four distinct phases are described in the usual HIT timeline, and the anticoagulation strategy chosen for CPB depends on the phase in which the patient is categorized. In this sense, we developed an institutional protocol covering each phase. It consisted of the use of a non-heparin anticoagulant such as bivalirudin, or the association of unfractionated heparin (UFH) with a potent antiplatelet drug such as tirofiban or cangrelor. Temporary reduction of anti-PF4 with intravenous immunoglobulins (IvIg) has recently been described as a complementary strategy. In this article, we briefly described the pathophysiology of HIT and focused on the various strategies that can be applied to safely manage CPB in these patients.

GTH 2021 State of the Art-Cardiac Surgery: The Perioperative Management of Heparin-Induced Thrombocytopenia in Cardiac Surgery

Heparin-induced thrombocytopenia (HIT) is a severe, immune-mediated, adverse drug reaction that paradoxically induces a prothrombotic state. Particularly in the setting of cardiac surgery, where full anticoagulation is required during cardiopulmonary bypass, the management of HIT can be highly challenging, and requires a multidisciplinary approach. In this short review, the different perioperative strategies to run cardiopulmonary bypass will be summarized.

Heparin-Induced Thrombocytopenia: A Review of New Concepts in Pathogenesis, Diagnosis, and Management

Knowledge on heparin-induced thrombocytopenia keeps increasing. Recent progress on diagnosis and management as well as several discoveries concerning its pathogenesis have been made. However, many aspects of heparin-induced thrombocytopenia remain partly unknown, and exact application of these new insights still need to be addressed. This article reviews the main new concepts in pathogenesis, diagnosis, and management of heparin-induced thrombocytopenia.

How would we treat our own heparin-induced thrombocytopenia during cardiac surgery?

The aim of this article is to provide a comprehensive review of the current state of knowledge on heparin-induced thrombocytopenia (HIT) in cardiac surgery. The management of HIT patients undergoing cardiac surgery with cardiopulmonary bypass is complex and requires an interdisciplinary and patient-tailored approach because available evidence is limited and current anticoagulation strategies have potential risks. An index case is used to discuss both the established and new perioperative therapeutic options in HIT patients undergoing urgent cardiac surgery with cardiopulmonary bypass.

Potential and Limitations of the New P2Y12 Inhibitor, Cangrelor, in Preventing Heparin-Induced Platelet Aggregation During Cardiac Surgery: An In Vitro Study

BACKGROUND

Heparin-induced thrombocytopenia (HIT) can put cardiac surgery patients at a high risk of lethal complications. If anti-PF4/heparin antibodies (anti-PF4/Hep Abs) are present, 2 strategies exist to prevent intraoperative aggregation during bypass surgery: first, using an alternative anticoagulant, and second, using heparin combined with an antiaggregant. The new P2Y12 inhibitor, cangrelor, could be an attractive candidate for the latter strategy; several authors have reported its successful use. The present in vitro study evaluated cangrelor's ability to inhibit heparin-induced platelet aggregation in the presence of anti-PF4/Hep Abs.

METHODS

Platelet-poor plasma (PPP) from 30 patients with functional anti-PF4/Hep Abs was mixed with platelet-rich plasma (PRP) from 5 healthy donors.Light transmission aggregometry was used to measure platelet aggregation after adding 0.5 IU·mL of heparin (HIT) to the plasma, and this was compared with samples spiked with normal saline (control) and samples spiked with cangrelor 500 ng·mL and heparin 0.5 IU·mL (treatment). Friedman test with post hoc Dunn-Bonferroni test was used for between-group comparisons.

RESULTS

Heparin 0.5 IU·mL triggered aggregation in 22 of 44 PPP-PRP mixtures, with a median aggregation of 86% (interquartile range [IQR], 69-91). The median aggregation of these 22 positive samples' respective control tests was 22% (IQR, 16-30) (P < .001). Median aggregation in the cangrelor-treated samples was 29% (IQR, 19-54) and significantly lower than the HIT samples (P < .001). Cangrelor inhibited heparin-induced aggregation by a median of 91% (IQR, 52-100). Cangrelor only reduced heparin-induced aggregation by >95% in 10 of the 22 positive samples (45%). Cangrelor inhibited heparin-induced aggregation by <50% in 5 of the 22 positive samples (22%) and by <10% in 3 samples (14%).

CONCLUSIONS

This in vitro study found that cangrelor was an unreliable inhibitor of heparin-induced aggregation in the presence of anti-PF4/Hep Abs. We conclude that cangrelor should not be used as a standard antiaggregant for cardiac patients affected by HIT during surgery. Unless cangrelor's efficacy in a particular patient has been confirmed in a presurgery aggregation test, other strategies should be chosen.