Mechanical circulatory support (MCS) with the Impella microaxial pump in the setting of cardiogenic shock/cardiac arrest (CS/CA) is accompanied by substantial risk of life-threatening complications, including hemolysis, thrombotic and bleeding events. Previous studies in patients on durable MCS suggest that device-induced platelet dysfunction plays a major contributory role in the development of such events and that selected markers of platelet function have the potential to stratify patients according to an elevated risk of adverse events. To date, the potential clinical utility of markers of altered platelet function in patients supported with an Impella pump is unexplored. The proposed study will analyze changes in platelet function in the setting of Impella support (primary aim) and possibly identify a platelet function profile indicative of patients at high-risk to develop adverse events (secondary aim). The study is a prospective observational study. Changes in the expression levels of markers of both platelet activation and aggregation in patients supported with an Impella pump will be measured. Data will be longitudinally measured: pre-implant (before Impella implantation) and then after 24, 48 and 72h of Impella support. Markers that will be analyzed include surface platelet receptors and platelet microRNAs. Experimental data will be correlated with clinical outcomes, including the occurrence of adverse events. This study will provide mechanistic insights into the effect of Impella support on the protein and miRNA expression of platelets. The intention is to get a better understanding of distinct pathways of platelet function related to Impella support and their relationship to adverse events. Our data might open the perspective for the future clinical use of markers of platelet function to enhance the early recognition of patients at high risk of developing an adverse event and the definition of novel, personalized therapeutic strategies targeted to platelet biology to prevent their occurrence.