Atrial Fibrillation After Atrial Flutter Ablation
What is the incidence of atrial fibrillation (AF) after successful ablation of the cavotricuspid isthmus for typical atrial flutter (AFL)?
The meta-analysis consisted of 48 studies (1996-2015), which described the outcome of patients undergoing catheter ablation for typical AFL. The study population was made up of 8,257 patients (mean age, 63 years; 79% male). The acute procedural endpoint was demonstration of bidirectional conduction block (as opposed to only termination of AFL).
Over a mean follow-up of about 2.5 years, the incidence of AF post AFL ablation was 23% and 52% in patients without and with a prior history of AF, respectively. Studies with longer follow-up found that the incidence of de novo AF was significantly higher (14% or 26%, when follow-up was <2 or >2 years). The incidence of de novo AF also varied depending on the intensity of rhythm assessment: 12% (electrocardiography, symptoms), 19% (up to 7 days of monitoring per year, irrespective of symptoms), and 45% (>7 days of monitoring period per year, including implantable devices).
The authors concluded that the incidence of AF after catheter ablation of AF is high, and that AF detection increases with more intense monitoring methods.
In most cases, AFL is triggered by episodes of AF, commonly from the pulmonary veins. Catheter ablation of the cavotricuspid isthmus for typical AFL is highly efficacious, durable, and associated with a low risk of complications. However, elimination of AFL cannot be expected to reduce the incidence of AF. It follows that patients with pre-existing AF are likely to develop AF over follow-up. It also should not be surprising that a significant number of patients without clinical AF before AFL ablation develop AF over long-term follow-up. The authors also raise an important issue regarding anticoagulation in patients who have undergone successful AFL ablation, but have not developed AF. Since the incidence approaches 50%, the authors advocate utilization of the current risk stratification schemes even in the absence of documentation of AF. This important question should be addressed by randomized trials.
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