The current study evaluates quantitatively the impact that intermittent aortic valve (AV) opening has on the thrombogenicity in the aortic arch region for patients under left ventricular assist device (LVAD) therapy. The influence of flow through the AV, opening once every five cardiac cycles, on the flow patterns in the ascending aortic is measured in a patient-derived computed tomography image-based model, after LVAD implantation. The mechanical environment of flowing platelets is investigated, by statistical treatment of outliers in Lagrangian particle tracking, and thrombogenesis metrics (platelet residence times and activation state characterized by shear stress accumulation) are compared for the cases of closed AV versus intermittent AV opening. All hemodynamics metrics are improved by AV opening, even at a reduced frequency and flow rate. Residence times of platelets or microthrombi are reduced significantly by transvalvular flow, as are the shear stress history experienced and the shear stress magnitude and gradients on the aortic root endothelium. The findings of this device-neutral study support the multiple advantages of management that enables AV opening, providing a rationale for establishing this as a standard in long-term treatment and care for advanced heart failure patients.