Final answer:
Anti-platelet agents are more effective in the arterial circulation because of the higher shear stress in arteries, which is caused by higher blood pressure and promotes platelet activation and aggregation, leading to thrombus formation.
Step-by-step explanation:
The reason why anti-platelet agents are more effective at reducing thrombus formation in the arterial than venous circulation is due to the higher shear stress in arteries. This higher shear stress in arteries, caused by significantly higher blood pressure compared to veins, promotes the activation and aggregation of platelets leading to thrombus formation. Consequently, the use of anti-platelet agents can more effectively prevent platelet activation and aggregation, thereby reducing arterial thrombus formation. Conversely, veins have lower pressure and less shear stress, which leads to slower blood flow and less platelet activation, making venous thrombus formation less dependent on platelets and more on coagulation factors.