With the advent of the NOACs, one of the situations many physicians will no doubt face is switching patients from warfarin to one of the NOACs, or perhaps in rare cases, vice versa.  When moving patients from warfarin to one of the NOACs, the warfarin should be stopped and the new agent initiated when the INR is still ≥2.0, ie, before the anticoagulation level becomes sub-therapeutic.

Rothman SA. Am J Med 2013; 126: 00-00.