We recommend therapeutic anticoagulation for at least 4 weeks after successful cardioversion to sinus rhythm, rather than no anticoagulation, regardless of the baseline risk of stroke (Grade 1B). Decisions about anticoagulation beyond 4 weeks should be made in accordance with our risk-based e568S Antithrombotic Therapy for Atrial Fibrillation ies assessed oral anticoagulation at very-low INR targets or xed low doses compared with adjusted- dose anticoagulation targeted at an INR of 2.0 to 3.0 and found that anticoagulation targeted at an INR of 2.0 to 3.0 was more effective in reducing the risk of stroke.164 Observational studies have shown that the risk of ischemic stroke is much greater once INR levels are , 2.0 and that there are no appre- ciable gains in ef cacy with levels . 2.0. However, there is a sharp increase in the risk of bleeding com- plications, particularly intracranial hemorrhage, as INR levels rise to . 3.0 to 4.0.165-169 A target INR value of 2.0 will result in patients spending a substan- tial proportion of time at subtherapeutic INR levels (ie, ,2.0).170 Given that bleeding risk does not rise substantially until INR levels are .3.0, and particu- larly .4.0, these data from AF populations support an optimal target INR range of 2.0 to 3.0, with a tar- get value of 2.5 to maximize the time spent in the optimal INR range.165-170 5.2 Time in Therapeutic Range For a full discussion of the importance of time in therapeutic range while on adjusted-dose VKA therapy, see Ageno et al171 regarding oral antico- agulation in this guideline. 