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Ablation reduced stroke risk in AF patients
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In a new study, catheter ablation reduced the risk for stroke among patients with atrial fibrillation.
T. Jared Bunch, MD, of the Intermountain Heart Institute in Salt Lake City, and colleagues also found that a patient with AF who underwent ablation had a similar long-term risk for stroke to a patient without AF, regardless of CHADS2 risk score.
The researchers enrolled 37,908 patients (mean age, 65 years) from the Intermountain Atrial Fibrillation Study Registry. Of those, 4,212 had AF and underwent ablation, 16,848 had AF and had not undergone ablation, and 16,848 had no history of AF. Each patient who underwent AF ablation was matched with four patients of the same sex and similar age who had AF but had not undergone ablation and four patients of the same sex and similar age who did not have AF.
The primary outcome was stroke. Mean follow-up was 2.9 years.
Among patients, 4.4% of those without AF, 6.3% of those with AF but without ablation, and 4.5% of those who had undergone ablation for AF experienced a prior stroke (P<.0001). At 1 year, 3.5% of AF patients who did not have ablation experienced a stroke vs. 1.4% of those with AF who underwent ablation and 1.4% of those without AF (P<.0001).
Regardless of age or CHADS2 profile, AF patients with ablation had a lower long-term risk for stroke compared with AF patients without ablation, with the greatest difference observed in patients aged younger than 60 years. Long-term risk for stroke among AF patients with ablation was similar to patients with no history of AF, Bunch and colleagues found.
“These data in part suggest that ablation, and the process and subsequent care associated with ablation, can favorably affect the natural history and consequences of AF,” the researchers wrote. “However, it must be emphasized that since these data are derived from a multicenter observation design, we do not have accurate data on long-term success rates of AF recurrence, particularly, subclinical AF.”
As to why ablation may have such a positive effect, the researchers wrote, “It is possible that ablation early in the disease process, by either maintaining sinus rhythm or significantly reducing AF burden, can stop the progression of the structural, anatomic, and functional changes in the atrium. This postulate is supported by serial echocardiographic assessments of atrial function over time after ablation.”
Disclosure: See the full study for a list of the researchers’ relevant financial disclosures.
Perspective
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Hugh Calkins, MD
This is an interesting study that provides valuable information to help inform the growing discussion regarding stroke risk, AF and catheter ablation. This study is impressive in large part due to the large number of patients involved and the careful analysis of the data.
I completely agree with the researchers’ recommendation that the results of this study should affect current recommendations concerning anticoagulation in patients undergoing AF ablation. The 2012 Heart Rhythm Society Consensus Document states clearly that all patients should be anticoagulated for the first several months after AF ablation. They also state that the decision to stop anticoagulants after this early post-procedure period should be based on the patient’s stroke risk profile and not on the perceived presence or absence of AF.
These recommendations reflect:
- AF recurrence after AF ablation is common and may occur late;
- Asymptomatic AF is far more common after AF ablation than before AF ablation; and
- A patient’s risk for stroke increases as he ages.
It is also important to recognize that the presence of AF is likely a stroke risk factor rather than a causative factor. Prior studies have clearly shown that strokes occur commonly in patients with a history of AF, despite the absence of any AF for months before or after the stroke event. Although this study showed that patients who had AF ablation had a lower stroke risk than those who did not, this should not be misinterpreted by physicians to mean that catheter ablation prevents strokes in patients with AF. This was not a prospective study and no attempt was made to assess how stroke risk was affected by whether the ablation procedure was 100% effective or a complete failure. It is striking that among patients who underwent AF ablation, the incidence of stroke during 3 years of follow-up was considerable and closely correlated with the CHADS2 score. In patients with a CHADS2 score of 4, stroke incidence was 9% during 3 years.
The results of this study are consistent with my experience. It is important to recognize that the decision regarding whether to stop anticoagulation in patients 2 or more months after AF ablation should be made with great care. Patients must be informed that, currently, there is not compelling data to suggest that anticoagulation can be safely stopped in patients who are at an increased risk for stroke based on the CHADS2 or CHADS2-VASc risk score. Patients must be informed of the current anticoagulation recommendations, and then they must make an informed decision based on their own values and preferences.
The authors are to be congratulated on an outstanding study that helps move this important discussion forward. Hopefully, prospective, randomized clinical trials will be performed over time and will provide us with the information we are all looking for.
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