Two recent retrospective studies evaluated the risk of thromboembolism in patients after cardio- version for AF lasting <48 hours. In 1 study (567 cardioversions in 484 patients), the risk of throm- boembolism was nearly 5 times higher in patients without therapeutic anticoagulation than in those on therapeutic anticoagulation with either warfa- rin or heparin, with no events in patients with a -VASc score of <2.S6.1.1-14 In the second study, for patients with AF lasting <48 hours and -VASc score 1, the overall event rate was low (0.4%), but this group accounted for 10 of the 38 thromboembolic events (26%) that occurred in the study.S6.1.1-13 These studies agree with prior studies of cardioversion in short-term In the absence of randomized trials, the risk of thromboembolic events should be weighed Recommendations for Prevention of Thromboembolism (Continued) COR LOE Recommendations CLINICAL STATEMENTS AND GUIDELINES against the risk of anticoagulant-related bleeding for the individual patient. 6.3. AF Catheter Ablation to Maintain Sinus Rhythm 6.3.4. Catheter Ablation in HF Recommendation for Catheter Ablation in HF Referenced studies that support the new recommendation are summarized in Online Data Supplement 7. COR LOE Recommendation IIb B-R AF catheter ablation may be reasonable in selected patients with symptomatic AF and HF with reduced left ventricular (LV) ejection fraction (HFrEF) to potentially lower mortality rate and reduce hospitalization for HF.S6.3.4-1,S6.3.4-2 NEW: New evidence, including data on improved mortality rate, has been published for AF catheter ablation compared with medical therapy in patients with HF. Recommendation-Specific Supportive Text (New) 1. 