Argatroban as Purge Solution in Patients With Heparin-Induced Thrombocytopenia on an Impella Device

Outcomes of systemic bivalirudin and sodium bicarbonate purge solution for Impella 5.5

BACKGROUND

Impella 5.5 (Abiomed; Danvers, MA) (IMP5) is a commonly used, surgically implanted, tMCS device that requires systemic anticoagulation and purge solution to avoid pump failure. To avoid heparin-induced thrombocytopenia (HIT) from unfractionated heparin (UFH) use, our program has explored the utility of bivalirudin (BIV) for systemic anticoagulation and sodium bicarbonate-dextrose purge solution (SBPS) in IMP5.5.

METHODS

This single center, retrospective study included 34 patients supported on IMP5.5 with BIV based AC and SBPS between December 1st 2020 to December 1st 2021.The efficacy and safety end points were incidence of development of HIT, Tissue Plasminogen Activator (tPA) use for suspected pump thrombosis, stroke, and device failure as well as clinically significant bleeding.

RESULTS

The median duration of IMP5.5 support was 9.8 days (IQR: 6-15). Most patients were bridged to HTX (58%) followed by recovery (27%) and LVAD implantation (15%). Patients were therapeutic on bivalirudin for 64% of their IMP5.5 support. One patient (2.9%) suffered from ischemic stroke and 26.5% (9) patients developed clinically significant bleeding. tPA was administered to 7(21%) patients. One patient in the entire cohort developed HIT.

CONCLUSIONS

Our experience supports the use of systemic BIV and SBPS as a method to avoid heparin exposure in a patient population predisposed to the development of HIT.

What is known in pre-, peri-, and post-procedural anticoagulation in micro-axial flow pump protected percutaneous coronary intervention?

Interest in the use of percutaneous left ventricular assist devices (p-LVADs) for patients undergoing high-risk percutaneous coronary intervention (PCI) is growing rapidly. The Impella™ (Abiomed Inc.) is a catheter-based continuous micro-axial flow pump that preserves haemodynamic support during high-risk PCI. Anticoagulation is required to counteract the activation of the coagulation system by the patient's procoagulant state and the foreign-body surface of the pump. Excessive anticoagulation and the effect of dual antiplatelet therapy (DAPT) increase the risk of bleeding. Inadequate anticoagulation leads to thrombus formation and device dysfunction. The precarious balance between bleeding and thrombosis in patients with p-LVAD support is often the primary reason that patients' outcomes are jeopardized. In this chapter, we will discuss anticoagulation strategies and anticoagulant management in the setting of protected PCI. This includes anticoagulant therapy with unfractionated heparin, direct thrombin inhibitors, DAPT, purge blockage prevention by bicarbonate-based purge solution, and monitoring by activated clotting time, partial thromboplastin time, as well as anti-factor Xa levels. Here, we provide a standardized approach to the management of peri-interventional anticoagulation in patients undergoing protected PCI.

Heparin-Induced Thrombocytopenia under Mechanical Circulatory Support by Large Impella for Acute Cardiogenic Shock

Despite the critical feature of heparin-induced thrombocytopenia (HIT) for patients on mechanical circulatory support, reports on its incidence and outcome are still scarce. Thus, we report on clinical features of HIT in patients under Impella 5.0 or 5.5 (Abiomed Inc., Danvers, MA, USA) (Impella 5+) support for acute cardiogenic shock (CS) by focusing on observed thrombotic events. Between November 2018 and December 2020, a total of 56 consecutive patients were enrolled in a single-center retrospective study. A total of 21 patients (37.5%) were tested for HIT, and 6 (10.7%) proved positive for HIT at 10.5 ± 2.89 days after the first heparin administration during current admission. Interestingly, thrombocyte counts dropped under Impella support in all groups (all cases, no HIT test, and HIT negative group: p < 0.001, HIT-positive group: p = 0.001). All HIT-positive patients were switched from heparin to argatroban. HIT-associated thrombotic events were observed in two cases resulting in Impella dysfunction due to pump thrombosis (n = 1) and left ventricular (LV) thrombus formation (n = 1). Under large Impella support, the prevalence of HIT was relatively high. Further, thrombocytopenia does not deliver a high specificity in the setting of Impella 5+ support. Considering HIT manifestation, a routine HIT test may be considered to avoid critical thrombotic adverse events.

Optimizing anticoagulation for patients receiving Impella support

Anticoagulation of patients treated with the Impella percutaneous mechanical circulatory support (MCS) devices is complex and lacks consistency across centers, potentially increasing the risk of complications. In order to optimize safety and efficacy, an expert committee synthesized all available evidence evaluating anticoagulation for patients receiving Impella support in order to provide consensus recommendations for the management of anticoagulation with these devices. The evidence synthesis led to the creation of 42 recommendations to improve anticoagulation management related to the use of the Impella devices. Recommendations address purge solution management, intravenous anticoagulation, monitoring, evaluation and management of heparin-induced thrombocytopenia (HIT), and management during combination MCS support. The use of a heparinized, dextrose-containing purge solution is critical for optimal device function, and a bicarbonate-based purge solution may be an alternative in certain situations. Likewise, intravenous (ie, systemic) anticoagulation with heparin is often necessary, although evidence supporting the optimal assay and target range for monitoring the level of anticoagulation is generally lacking. Patients treated with an Impella MCS device may develop HIT, which is more difficult to evaluate and treat in this setting. Lastly, the use of Impella with extracorporeal membrane oxygenation or for biventricular support creates additional anticoagulation challenges.