The purpose of this study is to determine whether dabigatran is associated with higher risk of bleeding in Asia area especially in China clinical practice and whether it need to set up a monitor system.

Dabigatran is administered in a fixed does without laboratory monitoring and is being compared with warfarin (international normalized ratio, but only hundreds of evidence from Asia events in several multicenter, prospective, randomized trails. It remains unclear that whether Dabigatran is safety in China clinical practice and no need of monitor test. We identified participants as those diagnosed as having nonvalved atrial fibrillation, and who initiated dabigatran after diagnosis.We followed up each individual from the first prescription of dabigatran until discontinued use or switch of anticoagulants, death, or other outcomes or until one year later. We categorized bleeding events as major and minor events according to anatomical position. We defined time to bleeding as days between the first dabigatran prescription and the date of the bleeding event. We analyzed the time to the first bleeding event, as well as the time to the first major hemorrhage, intracranial hemorrhage, gastrointestinal bleeding, hematuria, vaginal bleeding, hemarthrosis, hemoptysis, and epistaxis.

Inclusion Criteria:

1. Age>18 y at entry
2. AF documented as follows: The patients has a symptomatic episode of paroxysmal or persistent AF documented by 12-lead ECG, rhythm strip, pacemaker/implantable cardioverter-defibrillator electrogram, or Holter ECG
3. In addition to documented AF, patients must have ≥1 CHADS2-VAS scores
4. We identified participants as those diagnosed as having AF, and who initiated dabigatran after diagnosis
5. Written, informed consent

Exclusion Criteria:

1. History of heart valve disorders (ie, prosthetic valve or hemodynamically relevant valve disease)

2. Severe, disabling stroke, or any stroke within the previous 14d

3. Acute coronary syndrome within 1 year in AF patients

4. Conditions associated with an increased risk of bleeding

   1. Major surgery in the previous month
   2. History of intracranial, intraocular, spinal, retroperitoneal or atraumatic intra-articular bleeding
   3. Gastrointestinal hemorrhage or hematuria

5. Severe renal impairment (estimated creatinine clearace≤30ml/min)

6. Severe liver dysfunction

7. Alcohol abuse or drug addiction

8. Patients who have received an investigational drug at this time

9. Patients considered unreliable by the investigator or have a life expectancy less than the expected duration of the trail

We identified participants as those diagnosed as having artrial fibrillation, and who initiated dabigatran after diagnosis. The diagnosis of AF was defined as having inpatient or outpatient claims with primary or secondary International Classification of Diseases, Ninth Revision(ICD-9), code427.31.12. The CHADS2-VAS score is calculated as the sum of all points for a given patient and need >=1. A history of previous stroke or transient ischemic attack is assigned 2 points; congestive heart failure, hypertension, age of 75 years or older, and diabetes are each assigned 1 point.