IMPELLA, Complications and Tolerance

Myocardial infarction complicated by cardiogenic shock (AMICS) is associated with high rates of morbidity and mortality. To provide hemodynamic support in these cases, intravascular microaxial left ventricular assist devices, such as Impella® CP and Impella 5.0-5.5, are frequently used, either alone in cardiogenic shock (CS) or in combination with veno-arterial ECMO (known as ECMELLA) for left ventricular unloading. Recent observational studies and randomized controlled trials have suggested improved survival rates with the use of Impella® in cardiogenic shock patients.

Despite the growing use of these devices, complications in clinical practice remain frequent. Due to the need for deep arterial access (14F for Impella CP and 21F for Impella 5.0) via femoral or axillary routes, as well as the necessity of anticoagulation, hemocompatibility-related adverse events (HRAEs) such as ischemic complications and bleeding are common, occurring in 18% and 44% of patients, respectively. Hemolysis has been reported in up to 32% of cases, while stroke affects up to 13%. Other less frequent complications include device deployment issues, pump thrombosis, implant site infections, and sepsis, all contributing to increased healthcare costs.

Achieving hemocompatibility between the patient's blood and the device remains a significant challenge despite advances in Impella technology. Balancing prothrombotic and prohemorrhagic forces at the blood/device interface is complex. This interface activates the coagulation cascade, generating a prothrombotic state, damaging von Willebrand multimers, and leading to hemolysis. The interplay of pump flow, pump speed, patient risk factors, and clinical management (anticoagulation) further complicates hemocompatibility, often resulting in thrombotic or bleeding events such as hemorrhagic stroke, circuit clots, or ischemic stroke.

Although the occurrence of HRAEs is well documented, particularly in the case of severe events like stroke, there is still an incomplete understanding of the factors driving these complications in modern clinical practice. Further research is needed to better delineate the risk factors and improve outcomes for patients receiving Impella support.