What is Catheter Ablation Success and What are the Implications
June 3, 2010 6:15 AM CT
By Christine Welniak and Mellanie True Hills
Healthcare providers at Heart Rhythm Society 2010 seemed to be grappling with what constitutes “success” following catheter ablation. Traditionally success has been defined as the absence of atrial fibrillation (AF) episodes and the ability to discontinue antiarrhythmic drugs. That is, success equates to a cure. “Cure should be the goal of any interventional treatment,” says Anne Curtis, M.D., who spoke at this HRS session.
Many patients experience some afib or atrial flutter in the three months following either catheter ablation or surgery for afib. This is called the “blanking period”, and AF episodes during this period are known as “early recurrence”. According to Dr. Curtis, early recurrence does not mean that ablation has failed—although not having early recurrence suggests that the ablation will ultimately be considered a success.
Some physicians perform another ablation during the blanking period if the patient experiences early recurrence afib or flutter. However, Dr. Curtis advises patients to hold off on such “repeat” ablations during the blanking period since early recurrence is so common. She also noted in her HRS presentation that there is no agreement among doctors on whether patients should remain on antiarrhythmic drugs during this time. She counseled physicians to stop the medication three months after the procedure to determine if the patient’s atrial fibrillation was indeed cured.
An ECG (electrocardiogram), which is used to record the rhythm of the heart, is essential to determine whether ablation has been successful as individuals may continue to have afib episodes after the blanking period but just not feel them. In fact, it’s estimated that these “asymptomatic” events, those which are not felt, occur 4.5 times more often than symptomatic episodes. If patients continue to have atrial fibrillation, can the procedure be considered a success?
Implications of the Definitions of Success
Some doctors say that whether or not the procedure is a success ultimately depends on the patient. The ablation may not eliminate AF, but it could significantly reduce the symptoms, such as palpitations, rapid heart beat, fatigue, dizziness, and others. So while the ablation may not be a success based on a strict medical definition, the patient may consider it a success due to a significantly reduced afib burden and the ability to return to a normal lifestyle.
However, there are some medical implications, such as the need for stroke prevention if the procedure is not a complete success. Atrial fibrillation puts people at risk of a stroke, and those with afib have more severe and debilitating strokes, so doctors must decide whether or not those who are still having some afib should remain on anticoagulant medications, such as warfarin.
Many doctors base their decision on an individual’s CHADS2 score, which is a composite of a patient’s risk factors for stroke. According to Dr. Jennifer Cummings, who spoke at HRS, “Very low risk patients may be considered for discontinuation of warfarin. Very high risk patients may need to remain on warfarin. Patients at moderate risk are the issue.” Doctors must determine whether the benefits of warfarin for stroke prevention outweigh the risk of bleeding. However, Dr. Cummings stated that doctors have yet to reach a consensus on how to treat these patients.
In several other HRS sessions, doctors indicated that they wouldn’t think twice about putting moderate risk, and maybe even low risk, patients on dabigatran, a warfarin-replacement that is currently under FDA review. It was shown in the Randomized Evaluation of Long-Term Anticoagulant Therapy (RE-LY) trial to be safer and more effective than warfarin.
Success Is In the Eye of the Beholder
Ultimately you determine whether your afib treatment is successful, so it’s important to discuss with your doctor what success means to you. Does it mean being free from AF, free from symptoms, or just reduced afib burden? And how will that success be measured—by an in-office ECG, a 24- or 48-hour Holter monitor, or a longer-term event monitor—and at what intervals and for how long?
Monitoring and measuring of success is still a complicated and controversial issue. In general, the longer the monitoring, the better, since asymptomatic episodes are more likely to be picked up. At HRS last year, Dr. James Edgerton presented his research on monitoring after afib surgery, ranging from 1- to 90-days, and that 14-day monitoring appeared to be optimal. And in research presented at HRS this year, seven-day monitoring appeared to be a minimum. Jessiciah Windfelder, of the University of Utah, presented research that received recognition from HRS and that showed that simple 48-hour monitoring after catheter ablation is not enough for some patients. With 8-day monitoring, there were no recurrences during the first 48 hours, but during days 3-8, 8% of patients had AF recurrences, with 37.5% of those being asymptomatic.
It’s also important to discuss whether, and at what point, another ablation may be performed. According to Dr. Curtis, “There’s a substantial minority of patients—25%–30%—who will need a repeat [ablation].” She added that patient preference is important. That’s one thing doctors agree on.
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Christine Welniak writes about atrial fibrillation and other heart diseases/conditions for patients, medical professionals, and investors.
Mellanie True Hills is founder and CEO of StopAfib.org and an atrial fibrillation survivor.