Predictors of Very Late Recurrence of Atrial Fibrillation After Successful Catheter Ablation
February 3, 2011 — A major focus of the recent Boston AF Symposium was the durability of catheter ablation. Studies discussed there by Dr. David Wilber, of Loyola University Medical Center in Chicago, showed that up to 30% of patients could have very late recurrence of atrial fibrillation following catheter ablation. Very late recurrence, which is when atrial fibrillation resumes more than one year after ablation, may be the result of age, gender, type of afib, and existence of other heart conditions.
In two studies presented by Dr. Wilber, afib recurred for less than 15% of patients who had undergone catheter ablation, but in studies he presented from Mayo Clinic and the University of Pennsylvania, the very late recurrence rate was about 30%.
Very late recurrence differs from early or late recurrence. Early recurrence occurs within three months of catheter ablation and is related to tissue inflammation that arises from ablation. If atrial fibrillation returns during this period, it usually subsides after the tissue has healed.
If afib recurs during the three to 12 months after ablation, it is characterized as late recurrence. Late recurrence is not uncommon following pulmonary vein isolation, which is the cornerstone of catheter ablation. Pulmonary vein isolation entails creating scars on atrial tissue (“lesion lines”) that will prevent abnormal heart rhythms from circulating in the heart. Even though doctors confirm that electrical conduction has been blocked during the procedure, the pulmonary veins can “re-connect” in the three to 12 months after catheter ablation. In fact, about 30% of patients undergo a repeat procedure within the first year.
Results from the studies presented by Dr. Wilber suggest that reconnection of the pulmonary veins is not the sole reason for very late recurrence.
Factors Associated with Very Late Recurrence
Hypertension (high blood pressure) and high cholesterol were correlated with very late recurrence of atrial fibrillation in a study performed at St. Luke’s-Roosevelt Hospital Center in New York. Doctors followed 264 patients who had been free of afib and off antiarrhythmic medication at one year following catheter ablation. At 28 months, atrial fibrillation had recurred for 8.7% of them. Actuarial analysis predicted that recurrence would increase to 25.5% of patients at five years.
Analysis showed that hypertension and high cholesterol predicted the recurrence. Specifically, 70% of patients who had very late recurrence of atrial fibrillation had hypertension compared to only 39% of patients who remained free of afib. Similarly, 61% of patients who had very late afib recurrence had high cholesterol compared to only 30% who were in normal sinus rhythm. Since patients with very late recurrence also had reconnection of the pulmonary veins, the authors of the study hypothesized that hypertension and high cholesterol might “enhance vulnerability” to atrial fibrillation.
The size of the left atrium has also been shown to predict recurrence for certain patients. Mayo Clinic followed 428 patients with paroxysmal atrial fibrillation and 356 patients with persistent or longstanding persistent atrial fibrillation after catheter ablation. At two years, 29% of patients with paroxysmal afib had a recurrence, and only a large left atrium (>45 mm) was associated with this recurrence. For all patients, diabetes and persistent afib were predictors of very late recurrence.
Although obstructive sleep apnea has been linked to low long-term success rates for atrial fibrillation catheter ablations, none of the long-term outcomes discussed at the Boston AF Symposium identified sleep apnea as a predictor of very late recurrence of afib.
Persistent Afib More Likely to Lead to Recurrence
Patients with persistent atrial fibrillation are more likely to face very late recurrence than patients with paroxysmal afib. According to Dr. Wilber, a multicenter study of 1,404 patients who underwent catheter ablation showed that patients with persistent or longstanding persistent afib had a two-fold higher risk of very late recurrence compared to patients with paroxysmal afib. In addition, female gender and hypertension predicted recurrence of atrial fibrillation in those with persistent afib but not in those with paroxysmal atrial fibrillation.
In a University of Pennsylvania study, the overall atrial fibrillation recurrence rate for 123 patients was 7% per year. By five years, 29% of patients had experienced recurrence. The patients who had very late recurrence were older, had larger left atriums, and a higher number of afib triggers than individuals who remained in normal sinus rhythm. Analysis showed that only age and persistent atrial fibrillation predicted the recurrence.
In the Mayo Clinic study mentioned earlier, persistent afib was also shown to predict very late recurrence. In addition, patients with persistent atrial fibrillation tended to face a higher recurrence rate as time went on. Specifically, 37% of persistent patients had recurrence at one year, and this increased 20 percentage points, to 57%, at two and a half years. Comparatively, only 27% of paroxysmal atrial fibrillation patients had recurrence at one year, and this increased only 12 percentage points, to 39%, at two and a half years.
Implications of Very Late Recurrence
Based on the research discussed above, Dr. Wilber believes that doctors should consider nonablation strategies to halt the progression of atrial fibrillation. These include controlling high blood pressure, encouraging weight loss, and treating sleep apnea. In addition, patients who are at high risk for stroke should stay on anticoagulant medication, such as Coumadin (warfarin) or Pradaxa (dabigatran), following catheter ablation.
The data Dr. Wilber presented suggests that earlier diagnosis and treatment of atrial fibrillation is important to improving long-term outcomes. These studies demonstrate that once atrial fibrillation is classified as persistent, it is harder for doctors to treat.
In our video interview with Dr. Wilber at Heart Rhythm Society 2009, he said, “One of the thoughts about afib that’s paroxysmal is that many patients (up to 50% over ten years) may ultimately develop more persistent forms of atrial fibrillation. There is a window of opportunity to treat and suppress atrial fibrillation that may be missed if you keep putting off decisions about what you want to do until your atrial fibrillation becomes more established.” These studies that he presented at Boston AF Symposium about very late recurrence back up his earlier comments.
See related studies and information:
- Long-Term Outcome Following Successful Pulmonary Vein Isolation (St. Luke’s-Roosevelt Hospital Study) — Requires Registration
- Long-Term Outcome of Atrial Fibrillation Ablation: Impact and Predictors of Very Late Recurrence (Mayo Clinic study) — Requires Registration
- Impact of Type of Atrial Fibrillation and Repeat Catheter Ablation on Long-Term Freedom from Atrial Fibrillation: Results from a Multi-Center Trial
- Long-Term Outcome after Successful Catheter Ablation of Atrial Fibrillation (University of Pennsylvania study)
- Video Interview with Dr. David Wilber at Heart Rhythm 2009