Atrial fibrillation (AF), which affects approximately 3-6 million people in the United States, is a risk factor for thromboembolic events including stroke, cardiovascular events, and death. This condition poses a significant public health threat, accounting for over 454,000 hospitalizations annually in the United States alone.
To reduce the risk for thromboembolic events associated with AF, guidelines recommend long-term or no oral anticoagulation therapy for patients. There is, however, no consensus as to how long patients with AF should remain on oral anticoagulants, particularly after successful catheter ablation, defined as no atrial arrhythmia recurrence.
Here are five things to know about anticoagulation after successful ablation for AF.
1. Current guidelines suggest the use of oral anticoagulants for at least 2 months after successful catheter ablation for AF.
Current guidelines from the American Academy of Family Physicians (AAFP) for the pharmacologic prevention of thrombotic events associated with AF include the use of direct oral anticoagulants (DOACs) as a first-line intervention. For patients with a mechanical valve, vitamin K antagonists, such as warfarin, are considered in place of DOACs as a first-line treatment option.
The ARISTOTLE study, a randomized, double-blind trial of 18,201 patients with AF and at least one additional risk factor for stroke compared the DOAC apixaban with warfarin. The study found apixaban significantly reduced the incidence of stroke or systemic embolism by 21%. Of note, though the study also found warfarin was effective at preventing stroke, there was a higher risk for bleeding with it than there was with DOACs. Along with increased bleeding risk, the adverse interactions of warfarin with foods and medications require regular outpatient monitoring, making it a less desirable treatment option. However, certain clinical situations such as the presence of prosthetic valves, a diagnosis of antiphospholipid syndrome, or an increased risk for gastrointestinal bleeding may warrant the use of warfarin as a first-line anticoagulant therapy in place of DOACs, despite its less desirable side effects.
Concerning anticoagulation therapy after catheter ablation for AF, the HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of AF recommends a DOAC or warfarin for at least 2 months after a successful procedure. After 2 months, the decision about the cessation or continued use of anticoagulation is based on the physician-patient shared decision-making according to the patient's risk factors for stroke.
2. Per studies demonstrating a low stroke rate in patients after successful catheter ablation for AF, long-term anticoagulation may not be necessary.
A multicenter study of 3355 patients who underwent catheter ablation for AF found that 2692 of them discontinued oral anticoagulation therapy between 3 and 6 months after successful ablation. Within this group, only two patients (0.45%) had an ischemic stroke, and no other thromboembolic events were reported. There was one major hemorrhage in the nonoral anticoagulation group (0.04%) vs 13 (2%) in the oral anticoagulation group (P < .0001). Although the authors of the study concluded that their findings favor discontinuing oral anticoagulation after successful AF ablation, even in patients who are at moderate to high risk for a thromboembolic event, they noted the need for future large randomized trials to confirm their findings.
A large propensity-matched retrospective study reviewed claims data from 24,244 patients with AF (12,122 had catheter ablation and 12,122 had cardioversion). In the catheter ablation group, 0.5% of participants experienced a periprocedural stroke or transient ischemic attack (TIA) within 30 days of ablation. The study also found a significantly reduced risk for stroke and TIA in the ablation group compared with the cardioversion group after the initial 30-day post-procedure period. These findings suggest the effectiveness of catheter ablation in addition to systemic anticoagulation for the prevention of TIA and stroke in the immediate 30-day post-procedure period.
3. Though research on discontinuing anticoagulation after successful ablation is promising, notable study limitations must be considered.
Though studies indicate the effectiveness of catheter ablation as a treatment for AF and support the cessation of oral anticoagulants several months after a successful procedure, certain study limitations exist and is not applicable in patients with high risk for stroke. One of the main limitations is that most of the studies included patients who were considered to be at low risk for stroke and other thromboembolic events.
To quantify stroke risk, patients are classified using the congestive heart failure, hypertension, age, diabetes, prior stroke or TIA or thromboembolism, vascular disease, age, sex category (CHA2DS2-VASc) score, a validated stroke risk assessment scale that is used for patients with AF. This scale is used to determine whether long-term oral anticoagulant treatment is necessary. Scores range from 0 to 6, and current guidelines recommend that oral anticoagulants are implemented for scores > 2.
In the previously discussed multicenter and retrospective studies, a limited number of patients in the treatment groups had a CHA2DS2-VASc score of > 2. In the multicenter study of 2692 patients who discontinued anticoagulation in the months after ablation, only 347 (13%) had a CHA2DS2-VASc > 2, indicating that they were already at low risk for stroke, regardless of anticoagulant use.
4. Although several studies indicate a low risk for thromboembolic events in patients who discontinue anticoagulation after successful ablation, certain situations warrant long-term anticoagulation.
A literature review examining the potential need for long-term anticoagulation after successful ablation for AF found that most guidelines support discontinuing oral anticoagulants a few months after a successful ablation. However, findings from this review do support the use of long-term, sustained anticoagulation for patients with a CHA2DS2-VASc score > 2 because they have risk factors that place them at increased risk for thromboembolic events.
It is important to note that this literature review had several limitations. There was a significant number (n = 13) of retrospective studies included in the review, increasing the risk of confounding and reporting bias. In addition, some patients may have experienced asymptomatic thromboembolic events, resulting in a potentially smaller number of cases due to underreporting. As such, the authors noted that future studies using monitoring devices (eg, smart watches, implantable cardiac monitors) could improve detection of asymptomatic events.
5. The bleeding risk associated with oral anticoagulants may outweigh the benefits of thromboembolic prevention.
A major reason some clinicians deprescribe anticoagulants soon after successful catheter ablation is due to the increased risk for bleeding. A Danish study looking at 4050 patients who underwent ablation for AF for the first time found discontinuing oral anticoagulants after 3 months did not significantly affect the rate of thromboembolic events but continuing anticoagulation resulted in severe bleeding risks. They recommended that randomized control trials were needed for further investigation.
To mitigate bleeding risk, current guidelines support a validated bleeding risk assessment at each follow-up visit. Specifically, the American College of Chest Physicians and the AAFP recommend using the hypertension, abnormal liver/renal function, stroke history, bleeding history or predisposition, labile INR, elderly, drug/alcohol concomitantly (HAS-BLED) tool. HAS-BLED scores range from 0 to 10; patients scoring > 5 points are considered to be high risk for bleeding, and therefore, long-term use of oral anticoagulants may not be appropriate.
Ultimately, the decision to stop or continue oral anticoagulation for AF after a successful catheter ablation is based on the patient's risk factors for stroke and bleeding. Though patients with a CHA2DS2-VASc score > 2 should be considered for long-term anticoagulation, the decision should be weighed against their bleeding risk score to determine whether the benefits of stroke prevention outweigh the increased risk for bleeding.
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Cite this: To Cease or Not to Cease Anticoagulation After Successful AF Ablation: 5 Things to Know - Medscape - May 25, 2023.