7. Demonstrated ability to tolerate dabigatran 150mg/BID (if CrCl >30ml/min), rivaroxaban 15mg QD (if CrCl 15-49 ml/min) and 20mg QD (if CrCl ≥50ml/min), or apixaban 5mg BID or 2.5 mg for subjects with ≥2 of the following: age ≥ 80 years, body weight ≤60kg, serum creatinine ≥1.5 mg/dl.