Heart Failure with preserved Ejection Fraction (HFpEF) is a type of heart failure in which the heart muscle is too stiff and does not relax properly during diastole. The prevalence of HFpEF among patients exhibiting heart failure symptoms is approximately 50% [1]. As pharmacological therapy has not conclusively demonstrated benefits in terms of morbidity and mortality in clinical trials, an innovative treatment has been proposed recently, based on a Mechanical Circulatory Support (MCS) device [2]. The goal of the considered blood pump is to discharge the heart by diverting a fraction of blood directly to the subclavian artery without passing through the left ventricle, in order to help the heart relax during diastole. The device has been designed, manufactured using additive manufacturing, and tested in order to verify its hydraulic performances [2]. The pump’s particularity lies in its low flow rate targeted operating conditions. This is detrimental to hemolysis and thrombosis phenomena. Therefore, the hemocompatibility of the discharge pump has been assessed, with in-sillico experiments [3]. In-vitro tests of hemolysis generation during operation are currently carried out. In this study, we now investigate thrombosis risks associated to the pump operating conditions. An accelerated thrombosis model specifically designed for blood pump, and based on the resolution of convection-diffusion-reaction equations, is used [4]. Activated platelets, activated plates and adenosine diphosphate are transported using the pump velocity field computed a priori. Results give interesting insight on the probability of occurrence of thrombosis and opens opportunities for the optimisation of the pump design.