7. Treatment with warfarin or other vitamin K antagonists. Patients who are on active treatment with warfarin or other vitamin K antagonists for conditions requiring anticoagulation will be switched, when not contraindicated, to a different form of anticoagulation, including low molecular weight heparin (LMWHs) (ex: enoxaparin, dalteparin) or oral anti-Xa drugs (ex: rivaroxaban or apixaban) Patients who switch to these alternative forms of anticoagulation will be eligible.