Heparin dosing in patients with Impella-supported cardiogenic shock

BACKGROUND

Impella™ is increasingly used in cardiogenic shock. However, thromboembolic and bleeding events are frequent during percutaneous mechanical circulatory support (pMCS).

OBJECTIVE

Therefore, we aimed to explore the optimal anticoagulation regime for pMCS to prevent thromboembolism and bleedings.

METHODS

This hypothesis-generating multi-center cohort study investigated 170 patients with left-Impella™ support. We (A) compared bleeding/thrombotic events in two centers with therapeutic range (TR-aPTT) activated partial thromboplastin time (60-80s) and (B) compared events of these centers with one center with intermediate range aPTT (40-60s).

RESULTS

After matching, there were no differences in patients' characteristics. In centers aiming at TR-aPTT, major bleeding was numerically lower with aPTT <60s within 48 h of left-Impella™ support, versus patients that achieved the aimed aPTT of ≥60s [aPTT ≥60s: 22 (37.3%) vs. aPTT<60s 14 (23.7%); Hazard ratio [HR], 0.62 (95%) CI, 0.28-1.38; p = 0.234]. Major cardiovascular and cerebrovascular adverse events (MACCE) did not differ between groups. In comparison of centers, TR-aPTT strategy showed higher major bleeding rates [TR: 8 (47.1%) vs. intermediate range: 1 (5.9%); HR, 0.06 (95%) CI, 0.01-0.45; p = 0.006]. MACCE were lower in the intermediate range aPTT group as well [TR 12 (70.6%) vs. intermediate range 5 (29.4%) HR, 0.32 (95%) CI, 0.11-0.92; p = 0.034].

CONCLUSION

This pilot analysis showed that lowering UFH-targets in left-Impella™ supported CS patients seems to be a safe and promising strategy for reducing major bleedings without increasing MACCE. This needs to be validated in larger, randomized clinical trials.

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.

Outcome of Patients Supported by Large Impella Systems After Re-implantation Due to Continued or Recurrent Need of Temporary Mechanical Circulatory Support

Despite the growing utilization of a large microaxial pump, i. e., Impella 5.0 or 5.5 (Abiomed Inc., Danvers, MA, USA) (Impella 5+) for patients with cardiogenic shock (CS), adverse events including the necessity of re-implantation have not been well discussed. In all 67 patients, in-hospital mortality was 52.2% (n = 35). Explantation of Impella 5+ was performed in 39 patients (58.2%), 22 of whom (32.8%) recovered under Impella 5+, and ten further patients (14.9%) survived after a successful transition to permanent mechanical circulatory support. Embolic events were considerable complications in each access. They occurred in the right arm after the removal of Impella 5+ via a subclavian artery (SA) (n = 3, 9.1%) or in the form of leg ischemia in patients with Impella 5+ via femoral artery (FA) (n = 2, 33.3%). Re-implantation was necessary for 10 patients (14.9%) due to 1) recurrent CS (n = 3), 2) pump thrombosis (n = 5), or 3) pump dislocation (n = 2), all of which were successfully performed via the same access route. In univariate analysis, FA access was a significant risk factor for Impella dysfunction compared to SA access (FA vs. SA, 42.9% vs. 9.8%, p < 0.05, odds ratio 6.88). No statistical difference of overall mortality was observed in patients with Impella 5+ re-implantation (n = 10) compared to patients with primary Impella 5+ support (n = 57) (80.0% (n = 8/10) vs. 47.4% (n = 27/57), p = 0.09). Our results suggested the acceptable clinical outcome of Impella 5+ despite a 15% re-implantation rate. Our observational data may merit further analysis of anticoagulation strategies, including risk stratification for embolic events.

Antithrombotic management for Impella® temporary ventricular assist devices: An analysis of an academic health-system experience

The use of acute mechanical circulatory support (MCS) has increased over the last decade. For patients with left-ventricular failure, an Impella^® (Abiomed, Danvers, MA) may be used to improve cardiac output. The purpose of this study is to describe Impella^® anticoagulation patterns and evaluate the safety and effectiveness of our protocol. This is a retrospective review of all adult patients who required at least 24 h of Impella^® support and received a heparin-based purge solution. In total, 109 patients were included in the final analysis. The most common indication for Impella^® device insertion was cardiogenic shock (76%) with the remaining patients receiving a device for a high-risk procedures; typically coronary artery bypass grafting or percutaneous coronary intervention. A total of 9 thrombotic events occurred among 8 (7%) patients and 50 bleeding events occurred among 43 (39%) patients, with the most common classification being BARC 3a (60%). A univariate analysis revealed that patients were more likely to bleed if they were less than 65 years old, had an indication of cardiogenic shock for Impella^®, inserted the device peripherally, were on dual antiplatelet therapy, or had an intra-aortic balloon pump prior to Impella^® insertion, the latter of which was confirmed with a multivariate analysis (OR 2.5 [1.072-5.830]; p = 0.034). For those monitored by anti-Xa, the presence of two or more values greater than 0.40 IU/mL was a risk factor for bleeding (p = 0.037). Our study identifies risk factors for bleeding in patients receiving temporary MCS with an Impella^®.

Clinical Use of Cangrelor After Percutaneous Coronary Intervention in Patients Requiring Mechanical Circulatory Support

BACKGROUND

Patients with cardiogenic shock after percutaneous coronary intervention (PCI) may require mechanical circulatory support (MCS). The combination of dual antiplatelet therapy with cangrelor and continuous anticoagulation required for MCS may increase the risk of bleeding.

OBJECTIVE

The objective of the study is to describe the complications and outcomes of patients who received cangrelor during MCS following PCI.

METHODS

This is a single-center, retrospective, observational case series of 17 patients who received cangrelor while on MCS from June 2017 to September 2019.

RESULTS

In a case series of 17 patients, 8 patients (47%) were supported with an Impella device and 4 patients (24%) with venoarterial (VA) extracorporeal membrane oxygenation (ECMO); 5 required (29%) concomitant VA ECMO and Impella support in the setting of cardiogenic shock. All patients received triple antithrombotic therapy with aspirin, heparin, and cangrelor. Cangrelor was commonly initiated at a median dose of 0.75 (range 0.5-4) µg/kg/min. Cangrelor dose adjustments included changes in increments up to 0.25 µg/kg/min with review of P2Y12 levels. A total of 10 patients (59%) experienced a bleeding event, most commonly located at the peripheral cannulation site (40%) and in the gastrointestinal tract (30%). Seven (70%) and 3 (30%) of the bleeding complications were classified as major and minor, respectively. No patient developed in-stent thrombosis during the hospitalization; 14 (82%) patients survived their MCS course.

CONCLUSION AND RELEVANCE

This case series suggests that cangrelor doses less than 0.75 µg/kg/min may be beneficial. Larger studies should evaluate alternative dosing regimens.