The goal of this study is to assess dabigatran pharmacokinetics in NVAF subjects with severe renal impairment defined as creatinine clearance between 15 and 30 mL/min calculated by Cockcroft-Gault formula.

The dabigatran etexilate dose of 75 mg BID was approved by the FDA for NVAF patients with severe renal impairment (CrCl 15-30 mL/min) , based on pharmacokinetic modeling and simulation.

Inclusion criteria:

• Subjects diagnosed with non-valvular atrial fibrillation with an indication for the anticoagulation therapy,
• Subjects with severe renal function impairment defined as creatinine clearance between 15 and 30 mL/min by Cockcroft-Gault formula,
• Male and female patients, age =18 years at entry

Exclusion criteria:

• Contraindications to Pradaxa (history of a serious hypersensitivity reaction to Pradaxa, active pathological bleeding, patients with mechanical prosthetic heart valve),
• Creatinine clearance <15ml/min or patients with End Stage Renal Disease on dialysis,
• Creatinine clearance >30 ml/min,
• Pre-menopausal women (last menstruation less than one year prior to informed consent) who are nursing or pregnant, or are of child bearing potential and are not practicing an acceptable method of birth control, or do not plan to continue using this method throughout the study. Acceptable methods of birth control include abstinence, tubal ligation, transdermal patch, intra uterine devices/systems (IUDs/IUSs), oral, implantable or injectable contraceptives, double barrier method and vasectomised partner,
• Patients who are participating in another drug study,
• Patients who have participated in another drug study within 6 weeks,
• Patients considered unreliable by the investigator concerning the requirements for participating in the study, including a follow-up interview,
• Any condition the investigator believes would not allow safe participation in the study,