Test Details: Clopidogrel is a part of antiplatelet therapy and is used to prevent strokes and heart attacks in individuals who are at risk of serious cardiovascular events. Clopidogrel is given in inactive form which is changed in the body to active form by CYP2C19 gene. Variations in CYP2C19 are most often associated with reduced enzyme activity and decreased metabolism of clopidogrel, leading to a low level of active drug and potentially ineffective treatment for risk of blood clots. This test is prescribed during intial treatment phase or in absence of expected response of treatment.