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CLINICAL STATEMENTS AND GUIDELINES

Circulation. 2024;149:e1–e156. DOI: 10.1161/CIR.0000000000001193 January 2, 2024 e57

Joglar et al 2023 Guideline for the Diagnosis and Management of Atrial Fibrillation

6.8.6 Anticoagulation of Typical AFL

Recommendations for Anticoagulation of Typical AFL* Referenced studies that support the recommendations are summarized in Online Data Supplement. COR LOE Recommendations

1 B-NR 1 For patients with AFL, anticoagulant therapy is

recommended according to the same risk profile used for AF.1–3

1 C-LD 2 In patients with AFL who undergo successful

cardioversion or ablation resulting in restoration of sinus rhythm, anticoagulation should be continued for at least 4 weeks postprocedure.1–4

1 A 3 Patients with typical AFL who have undergone suc-

cessful CTI ablation and have had AF previously detected before AFL ablation should receive ongoing oral anticoagulation postablation as indicated for AF.5,6

1 B-NR 4 Patients with typical AFL who have undergone suc-

cessful CTI ablation and are deemed to be at high thromboembolic risk, without any known previous history of AF, should receive close follow-up and arrhythmia monitoring to detect silent AF if they are not receiving ongoing anticoagulation in view of significant risk of AF.7–9

2b B-NR 5 In patients with typical AFL who have undergone

successful CTI ablation without any known previous history of AF who are at high risk for development of AF (eg, LA enlargement, inducible AF, chronic obstructive pulmonary disease [COPD], HF), it may be reasonable to prescribe long-term anticoagulation if thromboembolic risk assessment suggests high risk (>2% annual risk) for stroke.5,10–13

*This section refers to typical right-sided (CTI-dependent) AFL. Left-sided AFLs or atrial tachycardias (ATs) that develop after ablation of AF should be anticoagulated and managed in a manner similar to AF. “Typical” AFL is defined as either typical counterclockwise AFL when the macroreentrant circuit is dependent on the CTI using the isthmus from the patient’s right to left or typical clockwise AFL when the macroreentrant circuit is dependent on the CTI and uses this isthmus from the patient’s left to right. “Atypical” AFL is not dependent on the CTI and may arise from a macroreentrant circuit in the LA, such as perimitral or LA roof flutter or could be dependent on scar from previous ablation or surgery.

Synopsis AFL is a common atrial arrhythmia with a reported overall incidence of 88 per 100 000 person-years, and the incidence increases with age.14 AFL is 2.5 times more common in men than in women, and it is significantly more likely to occur in patients with underlying HF or COPD.14 Because of the high success rate and low recurrence rate of typical AFL after CTI ablation, catheter ablation is often used as a first-line treatment. The high effectiveness of CTI ablation may decrease thromboembolic risk so that many physicians may elect to discontinue oral anticoagulation >1 month after ablation in the absence of previously detected AF. However, the high incidence of new onset AF at some time after CTI ablation places this practice in question. Because AF may be subclinical or asymptomatic, patients could be at significant risk of thromboembolic events after ablation of typical AFL depending on thromboembolic risk factors. Catheter ablation of non–CTI-dependent AFL is technically more difficult, and “atypical” AFL or AT often occurs after AF ablation. These arrhythmias should be anticoagulated and managed in a manner similar to AF. Recommendations in this section refer to treatment of “typical” AFL.

Recommendation-Specific Supportive Text 1.	 AFL is associated with increased thromboembolic risk, but the exact risk and benefit of oral anticoagulation are difficult to ascertain as AFL and AF often coexist. In a population-based retrospective cohort study of patients with typical AFL and no history of AF, stroke occurred in 4.1% of patients with AFL compared with 1.2% of a general population-matched cohort (P<0.001).1 However, no large, randomized trials specifically address thromboembolic risks and benefits of anticoagulation in patients who have only AFL. In patients referred for ablation of typical AFL

without adequate previous appropriate anticoagulation, and no previous history of AF, TEE showed evidence for LA thrombus or dense spontaneous echocardiographic contrast in 3%.2 A systematic review identified thromboembolic event rates of 0% to 6% with cardioversion, with the highest incidence of thromboembolic events occurring 1 to 2 days postcardioversion of AFL.3 Echocardiographic studies reported LA thrombus in 0% to 38% and spontaneous echocardiographic contrast in 21% to 28% of cases.3 In 1 ablation study, thromboembolic events occurred in 13.9% of patients who did not receive anticoagulation.3 Observational studies report an elevated risk of stroke with AFL compared with a control group (RR, 1.4 [95% CI, 1.35- 1.46]) and elevated mortality risk (risk ratio, 1.9 [95% CI, 1.2-3.1]) with long-term follow-up.3

2 The incidence of embolism after cardioversion of

AFL is similar to that of AF (0.72% versus 0.46%; P=not significant).4 Atrial stunning has been noted on TEE in patients undergoing cardioversion of AF, with partial atrial recovery 15 to 30 days and full recovery 30 to 90 days postcardioversion.15 LAA stunning also occurs in patients with AFL, although it appears to occur at a lesser degree than what is seen with AF.16 Although limited data are available for AFL, 1 study demonstrated more forceful mechanical LAA contraction and absence of spontaneous echocardiographic contrast 2 weeks after ablation of persistent AFL, suggesting earlier recovery.17 Because LA and LAA stunning are thought to contribute to thrombus formation and thromboembolic events after cardioversion, continued anticoagulation is recommended early after conversion to sinus rhythm. 3.	 In a meta-analysis, the subsequent incidence of AF

after ablation of CTI-dependent AFL was 34% over 14 months. However, the incidence of AF after flutter ablation is significantly higher in patients with

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