About half of patients with paroxysmal atrial fibrillation (AF) who underwent cryoballoon-based pulmonary vein ablation in the STOP AF trial experienced early recurrences of AF. Within that early recurrence subset, those who chose repeat ablation were more likely to be AF-free at one year.

Lead author Jason G. Andrade, MD, of the Montreal Heart Institute, and colleagues published the results online Jan. 19 in Circulation: Arrhythmia and Electrophysiology.

STOP AF was a multicenter, randomized, controlled clinical trial designed to compare cryoablation with anti-arrhythmic drug therapy in patients with paroxysmal AF, which researchers defined as two or more episodes within two months before randomization. The prespecified analysis by Andrade et al used only the cryoablation arm of 163 patients.

They defined early recurrence as AF lasting more than 30 seconds occurring within the first three months of the index procedure. Later recurrence was AF of more than 30 seconds occurring between three and 12 months of the index procedure.

They found that 52 percent of patients experienced recurrent AF within the first three months of the index ablation procedure. For those patients, the first recurrence most often occurred in the first month post-ablation. Male sex was the only significant factor associated with early recurrence.

At 12 months follow-up, 25 percent of patients experienced AF recurrence after the three-month blanking period. Early recurrence was strongly associated with late recurrence, but 44 percent of the early recurrence patients remained AF free in the long term. Only current tobacco use was associated with late recurrence.

Thirty-six percent of the early recurrence group underwent reablation within the blanking period. One-year freedom from recurrent AF was lowest in the recurrent AF group who did not undergo reablation (44 percent) compared with 97 percent of the early reablation group and 87 percent of patients who had no early recurrences.  

Andrade and colleagues characterized the reablation results as hypothesis-generating only because patients chose the reablation procedure rather than being randomized. They emphasized that early reablation was not warranted in all patients.

“[W]hile early reablation was associated with improved long-term freedom from recurrent AF, nearly half of the patients with ERAF [early recurrence AF] did not develop late recurrence,” they wrote. “Given the potential for late cure, risks of early reablation should be balanced against a conservative strategy.”

They also pointed out the findings could not be generalized to patients with persistent AF.

Medtronic CryoCath funded the trial.