Compared with AF, atrial flutter is a more organized macro-reentrant arrhythmia often involving the tri- cuspid isthmus. Atrial flutter is less common than AF overall; however, patients with atrial flutter are at increased risk for developing AF, and the risk of stroke associated with atrial flutter is similar to that associated with AF.28 In a single-center series of 1121 patients referred for atrial flutter ablation and followed up for 2.1 2.7 years, 31.7% had AF before ablation and 23.2% of patients experienced AF after ablation for atrial flutter.446 5. Therapy with VKA has a narrow therapeutic win- dow. Patients who do not maintain an INR in the therapeutic range are at increased risk for both bleeding and thrombotic events. Time in thera- peutic range is an important metric indicating the overall time spent by a patient with an INR in the therapeutic range; time with subtherapeutic INRs confers greater risk of embolic events, whereas time spent with supratherapeutic INR confers risk of major bleeding. In the ACTIVE W trial (Atrial Fibrillation Clopidogrel Trial With Irbesartan for Prevention of Vascular Events), patients random- ized to warfarin who did not maintain >60% time in therapeutic range did not derive net benefit from A meta-analysis of data from the 4 seminal trials of DOACs confirmed this finding, observing substantially greater benefit of DOACs compared with VKAs when the center- based time in therapeutic range was <66% (31% versus 7% improvement in major bleeding).445 For patients who have documented suboptimal time in therapeutic range with VKA in the setting of AF and prior stroke or TIA, it is recommended to use a DOAC preferentially. 6. Patients with stroke or TIA in the setting of AF are at increased risk of recurrent ischemic stroke and at risk for ICH. 