Patients and control subject: Subjects will be recruited from the Coagulation Clinic. The participants will consist of patients attending the clinic for follow-up of their prescribed anticoagulation treatment. Patients to be studied will include subjects receiving warfarin anticoagulation, NOACs, heparin and anti-platelet therapy (aspirin, clopidrogel or other anti-platelet medications). Normal subjects receiving no anticoagulation will also be studied and will serve as the control group.