A stepwise approach of pulmonary vein isolation, ablation of complex fractionated electrograms and additional linear ablation lines was not superior to pulmonary vein isolation alone for termination of atrial fibrillation, according to results of the CHASE-AF study published in the Journal of the American College of Cardiology.
Because the long-term success rate of ablation to terminate persistent AF rarely exceeds 60%, Julie Vogler, MD, and colleagues designed the CHASE-AF study to compare the rate of arrhythmia-free survival for pulmonary vein isolation (PVI) alone vs. full defragmentation, which included PVI, ablation of complex fractionated electrograms and additional linear ablation lines in patients with persistent AF, even after initial PVI.
The study initially included 205 patients with persistent AF (151 men; mean age, 61.7 10.2 years) who underwent PVI between November 2010 and February 2013 at the University Heart Center Hamburg in Germany. Persistent AF was defined as AF lasting more than 7 days as documented on ECG.
In 52 patients, AF terminated during the first surgery. The remaining patients were randomly assigned to two groups: PVI alone (n = 78) or full defragmentation (n = 75). Recurrence of any atrial tachycardia after 3 months was the primary endpoint of the study.
Multiple ablations were required in some patients in both groups. To prevent unintentional blending of the two groups, the same procedure as the original was performed for each additional procedure. However, 10 patients were excluded from final analysis to avoid bias by crossover and 11 patients overall were lost to follow-up.
At the end of the study, 153 patients underwent 241 ablations (mean, 1.59 in the PVI-alone group, 1.55 in the full-defragmentation group). Eighty-eight patients received single ablation, 41 received two ablations and 24 received three ablations.
Sixty percent of patients (n = 45) in the full-defragmentation group achieved AF termination and 18 patients converted to sinus rhythm during ablation of complex fractionated electrograms. In 27 patients, AF converted to atrial tachycardia; cardioversion was required in 11 patients to terminate atrial tachycardia. According to the researchers, AF was not terminated in the remaining patients (n = 30). The full-defragmentation group experienced longer procedural and fluoroscopic duration and radiofrequency application time (P < .001 for all).
Number of procedures, whether single or multiple, did not impact the rate of arrhythmia-free survival (P = .468). In an intention-to-treat analysis, arrhythmia-free survival was similar for both groups (61.4% in the PVI-alone group vs. 58.3% in the full-defragmentation group). The success rate for patients with drug-free successful AF termination at 1 year was 51.4% in the PVI-alone group vs. 50% in the full-defragmentation group (P = .865). Overall, 6.6% of patients in the PVI-alone group and 11.3% in the full-defragmentation group had persistent AF and 29.5% vs. 26.8% had paroxysmal AF. The rate of atrial tachycardia was 8.2% in the PVI-alone group vs. 8.5% in the full-defragmentation group (P > .999). Twenty-one percent of patients in the PVI-alone group and 28.2% in the full-defragmentation group still required antiarrhythmic medication at the last follow-up evaluation (P = .364).
The researchers concluded that a strategy of PVI only or full defragmentation offers patients with persistent AF similar success rates, but full defragmentation required significantly longer procedure time, fluoroscopy duration and radiofrequency application.
In an editorial comment, Matthew Wright, MD, of the divisions of imaging sciences and biomedical engineering and cardiovascular medicine at King’s College London, wrote, “Although it may appear to a casual observer that the last decade of extensive [left atrial] ablation has come full circle back to PVI alone as an ablation strategy, encouragement remains for those of us who undertake ablation in these complex patients.”
Wright noted several limitations of the CATCH-AF study, including misdiagnosis of paroxysmal and persistent AF, the modified Bordeaux stepwise procedure that was performed in the full-defragmentation group and the misunderstood mechanisms of complex fractionated electrograms.
“Data such as [these] ... should spur us to critically re-examine for whom and how persistent AF ablation is undertaken,” he wrote. – by Tracey Romero
One researcher reports receiving research grants from Bayer Vital, Biosense Webster, Boehringer Ingelheim and St. Jude Medical and serving on the speaker’s bureau for Bayer Vital, Biosense Webster, Boehringer Ingelheim, Boston Scientific and St. Jude Medical. Wright reports no relevant disclosures.