The use of tMCS for patients with cardiogenic shock complicated AMI has increased dramatically despite lacking convincing evidence showing the clinical benefits [8, 9]. Moreover, the risk of stroke associated with tMCS devices has rarely been investigated.
To our knowledge, this is the first large sample study with robust analysis to investigate the risk of stroke for different models of tMCS devices used in AMI hospitalizations. The main finding are as follows: 1) IABP use alone does not increase the risk of overall, ischemic, and hemorrhagic stroke; 2) Impella use alone slightly increase the risk of overall, ischemic, and hemorrhagic stroke; 3) ECMO use associated with remarkably high risk of overall, ischemic, and hemorrhagic stroke; 4) hospitalizations younger than 50 years old, those without hypertension, and those with STEMI are at particularly high risk of stroke when treated with ECMO.
IABP continues to be the primary choice for tMCS during hospitalization for AMI. Despite uncertainties surrounding the survival advantages of IABP. [10, 11], it is somewhat reassuring that there is no indication of increased risk of stroke associated with its use.
The utilization of Impella has seen a significant rise, particularly following the IABP-SHOCK II trial [10, 11]. The publication of DanGer Shock[12] result will undoubtably further encourage clinician to deploy impella for the mechanical circulatory support in cardiogenic shock complicated AMI. The rate of stroke in impella treated group are 3.9% compared to 2.3% in standard care group[12]. Consistent to these findings, this large sample analysis reports an increased risk of stroke for the Impella treated AMI. and trending for more ischemic and hemorrhagic cerebral event. The impella device have a larger profile and necessitate the use of larger caliber catheters for implantation, which inevitability increases the risk of vascular complications. In addition, the implantation of the Impella device requires crossing the aortic arch and aortic valve, which may contribute to more stroke events.
Another potential reason for the increased occurrence of stroke with Impella could be attributed to hemodynamic changes. Unlike IABP, which augment the pulsatile blood flow, the continuous flow generated by Impella can lead to alterations in blood flow patterns, these abnormal flow pattern can create areas of stasis or turbulent flow, promoting the formation of blood clots thereby contributing to the increased risk of stroke.
Data are scarce regarding the utilization of ECMO in cases of cardiogenic shock complicated AMI [13–16]. Recent ECLS-ECMO trial[17] found that early routine ECMO was not superior to usual medical therapy alone in terms of mortality within 30 days. prior studies showed, the use of ECMO has been associated with a significantly increased risk of stroke[13, 18], with ischemic stroke being the most common type[19]. An analysis of 153 patients with VA-ECMO reported 8.4% acute ischemic stroke and 3.9% hemorrhagic stroke[20], which are comparable with the rates of stroke reported by our study.
The mechanisms through which ECMO use contributes to an increased risk of stroke are multifactorial. Firstly, similar to the altered blood flow pattern caused by Impella, continuous blood flow from ECMO can increase the chance of thrombosis. Secondly, the presence of foreign surfaces like gas exchange membranes and hollow fibers in the ECMO oxygenator can activate the coagulation cascade, leading to an increased risk of clot formation. Additionally, blood flow through the oxygenator may result in the destruction of red blood cells causing hemolysis. Even at a low level, hemolysis during ECMO support could potentially raise the risk of stroke[21]. lastly, when VA-ECMO peripheral cannulation causes the retrograde flow to the proximal aorta, it significantly increases the afterload on the left ventricle. This, in turn, can lead to left ventricular distension, blood flow stagnation, and the formation of thrombi within the left ventricle[15].
Furthermore, the use of anticoagulant medications, which are often essential to prevent clotting in patients with Impella and ECMO devices, can also increase the risk of hemorrhagic stroke, balancing the need for anticoagulation to prevent clotting with the risk of bleeding complication is challenging in managing patients treated with Impella and ECMO.
Given the potential severity of the stroke and its impact on patient outcomes, it is crucial that further research be conducted to better understand the risk factors, and prevention strategies associated with stroke in patients with Impella and ECMO use. In addition, advances in device technology should focus on minimizing the risk of stroke, this could involve the development of more biocompatible materials that reduce the formation of blood clots, as well as improving flow dynamic patterns. Additionally, optimizing anticoagulation protocols and monitoring strategies could help strike a balance between preventing clotting and minimizing bleeding complications.