Is it Safe to Discontinue Anticoagulation After Successful Ablation of Atrial Fibrillation?
March 16, 2019
- Summary: A review of the data regarding whether it is safe to discontinue anticoagulation after a successful afib ablation
- Reading time: 2–3 minutes
In his presentation at the American College of Cardiology 2019, Dr. Day started by sharing the 2017 AF Ablation Consensus Statement. It states that “Adherence to AF anticoagulation guidelines is recommended for patients who have undergone an AF ablation procedure, regardless of the apparent success or failure of the procedure.” (Heart Rhythm, Vol 14, No 10, October 2017) The recommendation is a Class 1 recommendation with the Level of Evidence being a C, which means that the benefits outweigh the risks, but that the evidence is not strong and may be based on expert opinion.
Dr. Day said that with those who are a CHA2DS2-VASc score of 0–1, meaning low risk, there generally is no question that anticoagulation is not needed. And for those who are a score of 4, meaning high risk, there generally is no question that anticoagulation is needed. However, what about those with an intermediate risk with a score of 2 or 3? We just don’t know the answer.
There have been many studies published from his center showing that stroke risk is low in those who have had successful afib ablations and discontinued anticoagulation, for whatever reason. Here are some examples of studies from his center:
- In a study by Dr. Day, 158 patients with a successful ablation and a CHADS2 score of 2 or 3 (average 2.8) stopped warfarin due to bleeding or other reasons. After two years of follow up, there was little difference in stroke rates between those with a successful ablation and those with no afib at all (1.9% vs. 1.8% with no afib). [Should Patients with a CHADS Score of 2 or 3 Continue to Take Warfarin Long-Term After a Successful Atrial Fibrillation Ablation, Heart Rhythm 2010.]
- More recently, another study from his center found that “In patients with AF and a prior CVA (cerebrovascular accident, a stroke), patients undergoing ablation have lower rates of recurrent stroke compared to AF patients not ablated.” [Five-year impact of catheter ablation for atrial fibrillation in patients with a prior history of stroke, Journal of Cardiovascular Electrophysiology, February 2018.]
- Another recent study from his center found that “Catheter ablation has shown to be an effective strategy for rhythm management and several small or retrospective studies have shown that stroke rates are decreased in ablated AF patients compared to those medically managed.” [Atrial Fibrillation Ablation and its Impact on Stroke, Curr Treat Options Cardiovasc Med 2018 Jan 24:20(1):2.]
- More studies from his center had similar findings.
- Atrial fibrillation ablation patients have long-term stroke rates similar to patients without atrial fibrillation regardless of CHADS2 score, Heart Rhythm September 2013.
- Patients Treated with Catheter Ablation for Atrial Fibrillation Have Long-Term Rates of Death, Stroke, and Dementia Similar to Patients Without Atrial Fibrillation, Journal of Cardiovascular Electrophysiology. 2011 Aug;22(8):839-45.
- Warfarin is Not Needed in Low-Risk Patients Following Atrial Fibrillation Ablation Procedures, Journal of Cardiovascular Electrophysiology. 2009 Sep;20(9):988-93.
Thus, the observations from his center regarding strokes after ablation are:
“(1) Ablation patients have a lower stroke risk. (2) Intermediate risk patients have a lower than expected stroke risk. (3) High stroke risk patients are still high risk.”
Other centers around the US and the globe have published similar results. And a study at the University of Pennsylvania even found this with patients with persistent and longstanding persistent afib.
Isn’t that enough data to know that it is safe to discontinue anticoagulation? Not really.
These observational studies (studies in which researchers observe an effect after the fact) have shown that if a patient discontinues anticoagulation, they seem to do OK, but we really don’t know. The problem is that none of these were randomized controlled studies (where patients were assigned to a group and followed). That is the gold standard in medicine.
Thus, prospective studies (forward-looking studies in which patients are identified up front and followed) are needed to confirm these results before doctors can feel comfortable discontinuing anticoagulation for those with successful ablations.
That is why a new study is so important. The Ocean (Optimal Anti-Coagulation for Enhanced-Risk Patients Post-Catheter Ablation for Atrial Fibrillation) Trial, led by Dr. Atul Verma, is expected to give us the data that we need to know whether or not this is safe. The study will be a large one, with more than 1,500 patients with successful afib ablations and moderate stroke risk. They will be randomized to either low dose aspirin (75-160 mg) or low-dose rivaroxaban (15 mg). They will have a brain MRI at the beginning, at one year, and at three years. Expected completion is December of 2021.
What should be done in the meantime, until we have the answers that the Ocean Trial should provide us in 2021?
Dr. Day recommended following the current guidelines, with these three recommendations:
- 2014 AHA/ACC/HRS AF Guidelines: “Antithrombotic therapy based on shared decision making, discussion of risks of stroke and bleeding, and patient’s preferences.”
- 2017 AF Ablation Consensus Statement: “Patients in whom discontinuation of anticoagulation is being considered based on patient values and preferences should consider undergoing continuous or frequent ECG monitoring to screen for AF recurrence.”
- 2019 Atrial Fibrillation Guidelines Focused Update: “A role in screening for silent AF may also exist for remote electrocardiographic acquisition and transmission with a “smart” worn or handheld WiFi-enabled device with remote interpretation…”
Until 2021, these are the best answers that we have.