Indiscriminate use of anti- biotics can be associated with the development of resistant organisms, Clostridium difficile colitis, unnecessary expense, and drug toxicity. The rate of transient bacteremia during or immediately after endoscopy is 2% to 5%, and the organisms typically identified are unlikely to cause IE.11,27,28 The rate of bacteremia does not increase with biopsy, polypectomy, or sphincterotomy. Some gastrointestinal procedures are associated with rates of bacteremia higher than that for simple endoscopy; these procedures include esophageal dilation (as high as 45%), sclerotherapy (31%), and endoscopic retrograde cholangiopancreatog- However, no studies have shown reduced rates of IE with antibiotic prophy- laxis. Surgery, instrumentation, or diagnostic pro- cedures that involve the genitourinary tract may cause bacteremia. In the absence of infection, the rate of bacteremia after urinary tract procedures is low. In patients with bacteriuria, antimicrobial therapy before elective procedures, including lith- otripsy, typically is provided.30 2.4.3. Anticoagulation for AF in Patients With VHD Recommendations for Anticoagulation for AF in Patients With VHD Referenced studies that support the recommendations are summarized in Online Data Supplement 2. COR LOE Recommendations For patients with AF and native valve heart disease (except rheumatic mitral stenosis [MS]) or who received a bioprosthetic valve >3 months ago, a non vitamin K oral anticoagulant (NOAC) is an effective alternative to VKA anticoagulation and should be administered on the basis of the patient s CHA2 For patients with AF and rheumatic MS, long-term VKA oral anticoagulation is recommended. 