In coronary pathology, persistent platelet hyperresponsiveness under antiplatelet therapy, which is often referred to as "antiplatelet resistance," is predictive of increased risk of thrombotic recurrence as well as hyper-Inhibition of this aggregation may be predictive of a hemorrhagic risk. But no study has shown that the adaptation of treatment based on platelet aggregation tests has a benefit: the management of antiplatelet treatments through the search for antiplatelet resistance (APR) is not recommended by the European Society of Cardiology (ESC) in the context of coronary angioplasty (IIIA), while this is a common practice in neurovascular pathology.

In peripheral arterial disease, several studies have shown that the existence of an APR is predictive of the occurrence of thrombotic events but not all. The investigators can therefore ask the question of the benefit of adaptation of antiplatelet therapy by biological monitoring to prevent the recurrence of thrombotic events. The platelet aggregation tests used mainly concern aspirin, via stimulation with arachidonic acid, or anti-P2Y12 (clopidogrel, ticagrelor, prasugrel), via stimulation with adenosine diphosphate (ADP). For the latter, a test via the measurement of the phosphorylation of a cytoplasmic protein called "VASP" is also used routinely, making it possible to further clarify the existence of platelet resistance to anti-P2Y12. Within the vascular medicine department, any discovery of a potential resistance to the anti-platelet treatment of a patient requires a therapeutic adaptation to overcome this phenomenon of "resistance", and to improve the phenomenon of anti-aggregation

Inclusion Criteria:

• Patients older than 18 years
• All patients who were hospitalized in the vascular medicine department and who received a search for antiplatelet resistance between April 2014 and November 2017.

Exclusion Criteria:

• Opposition to participation in the study
• Absence of follow-up after antiplatelet resistance testing

Patients who were hospitalized in the vascular medicine department and who received a search for antiplatelet resistance between April 2014 and November 2017.