MONTREAL, CANADA. It is estimated that about 38% of afibbers undergoing radiofrequency catheter ablation for atrial fibrillation (AF) experience recurrence of arrhythmias (AF, atrial flutter or left atrial tachycardia) within the first 3 months following the procedure (early recurrence). Experiencing early recurrences of atrial tachyarrhythmias (ERAT) does not necessarily indicate long-term failure, since about 50% of those having ERAT go on to experience long-term freedom from atrial arrhythmias. Thus it is common practice to exclude arrhythmia episodes occurring during a 3-month blanking period when evaluating the long-term success of ablation procedures.

Laurent Macle, MD and colleagues at the Montreal Heart Institute and Southlake Regional Health Center in Newmarket, Ontario recently published a review of 20 studies addressing the question why do some afibbers with ERAT go on to experience long-term success, while other do not? Following are the highlights of this review.

• The rate of late recurrence (arrhythmia recurrence between 3 and 12 months post-ablation) is significantly higher among ablates with ERAT (54%) than among those without ERAT (7%).
• ERAT may represent a transient and potentially reversible phenomenon due to proarrhythmic effects of the ablation (inflammation and autonomic nervous system modification).
• Longer term recurrence most likely reflects recovery of electrical conduction between pulmonary veins and the left atrium.
• Delayed success, as defined by late freedom from recurrent arrhythmias despite early recurrence, is associated with reverse electrical and structural remodelling related to the restoration of sinus rhythm and includes gradual shrinkage of the left atrium.
• Although it is generally assumed that lesions created by the ablation are fully healed as early as 2 weeks post-ablation, recent magnetic resonance imaging has shown that additional left atrial scar forms over the first 3 months post-ablation.
• Important predictors of ERAT are:

• Advanced age
• Hypertension
• Structural heart disease
• Genetic abnormalities (presence of 4q25 variant alleles)
• Persistent or permanent AF
• Duration of AF (time since diagnosis)
• Increased P-wave dispersion
• Left atrial enlargement
• Decreased left ventricular ejection fraction
• Post-procedure inflammation (elevated CRP level and body temperature)
• Incomplete pulmonary vein isolation
• AF not terminated at end of procedure or cardioversion required to do so
• Multiple AF foci outside pulmonary veins
• Absence of superior vena cava isolation.

• Predictors of late recurrence (3 to 12 months post-ablation) are:

• Same factors as for ERAT except for increased P-wave dispersion and post-ablation inflammation
• Male gender
• Higher number of previously ineffective antiarrhythmics
• Longer radiofrequency ablation time
• Incomplete vagal denervation
• Smaller percentage of left atrium isolated
• Early recurrence (ERAT).

Of particular interest is the finding that late recurrence is highly dependent on the timing of ERAT. Nearly all (98%) of 1298 patients undergoing ablation, who experienced ERAT during the 3rd month of the blanking period, went on to experience late recurrence. Another study demonstrated a significantly lower 6-month recurrence rate (24%) among patients who experienced immediate recurrence (within 3 days post-ablation) versus patients with recurrence between 3 days and 1 month. For this group, the 6-month recurrence rate was 70%. It has also been observed that early symptomatic arrhythmia recurrences lasting 6 hours or longer are associated with a 100% risk of late recurrence. Other observations of interest are:

• Administration of antiarrhythmics for 6 weeks post-ablation reduces the risk of severe arrhythmias, hospitalizations, and cardioversions during the treatment period, but has no effect on long-term outcome.
• Administration of anti-inflammatory corticosteroids for 3 days following the ablation procedure reduces the incidence of early AF recurrence during the first month, especially during the first 72 hours. The long-term (14 months) freedom from AF (without antiarrhythmics) was higher in the corticosteroid group (85%) than in the group not receiving corticosteroids (71%).
• Cardioversion for recurrent arrhythmia should preferably be done within 30 days of the recurrence.
• If re-ablation is needed, it should preferably be carried out 3 months after the initial (failed) procedure.

Andrade, JG, Macle, L, et al. Early recurrence of atrial tachyarrhythmias following radiofrequency catheter ablation of atrial fibrillation. PACE, Vol. 35, January 2012, pp. 106-16

Editor's comment: This review is clearly of huge importance to both the EP and the patient in determining the likely long-term outcome of a radiofrequency catheter ablation for AF. The observation that early recurrence is associated with post-ablation inflammation supports the recommendations in my Post-Ablation Care protocol, to avoid strenuous exercise, and supplement with natural anti-inflammatories during the recovery period.