Inclusion Criteria- Patients must give their informed consent and complete the case report form.
- Patients must be over the age of 20.
- Patients have clinical indications for warfarin therapy but do not have any prior warfarin treatment.
Exclusion Criteria- Patients who did not complete the informed consent form or the CRF
- Patients who are less than the age of 20.
- Patients who had prior or is currently on warfarin treatment.
- Patients who have hemorrhagic tendencies or hemorrhagic diseases defined as copious bleeding caused by viral or bacterial infections; cancer and hepatic dysfunction defined as GOP and GPT values three times higher than normal value
- Patients who has Vitamin K deficiency
- Female patients who is currently pregnant