Background: Pulmonary vein isolation (PVI) with radiofrequency (RF) catheter ablation is an established treatment for symptomatic persistent atrial fibrillation (AF). Data from the international CRYO4PERSISTENT AF trial had recently demonstrated 61% single-procedural success at 12 months in treating persistent AF with Cryoablation (Cryo) using the Achieve catheter with a Cryoballoon. We propose to conduct a local audit to study the efficacy of Cryo compared to RF ablation on procedure characteristics, arrhythmia recurrence and improvement of symptoms in patients undergoing persistent AF ablation.
Method: Forty-eight consecutive patients who had undergone Cryo (n=29) or radiofrequency (RF) catheter ablation (n=19) for persistent AF from 1 January 2018 to 29 October 2018 were included in this study.
Results: The median follow-up period was 11 months (Cryo: 10.9 ± 3.2 versus RF: 10.9 ± 2.2 months). The patients had comparable age (Cryo: 60.4 ± 11.3 versus RF: 57 ± 10.1 years old), gender distribution (Cryo: 20.7% versus RF: 15.8% female) and CHA2DS-VAS2c score (Cryo: 1.8 ± 1.2 versus RF: 1.3 ± 1.3). The left ventricular systolic function (LVSF) was also comparable between the two groups (normal LVSF: 51.7% Cryo versus 68.4% RF; mild to moderately impaired LVSF: 31% Cryo versus 26.3% RF; severely impaired LVSF: 10.3% Cryo versus 5.3% RF). Most patients underwent de novo ablation for persistent AF (Cryo 89.7% versus RF 68.4%, p=0.06). In the Cryoablation group, two main strategies were used, which were PVI only (n=14) or PVI and roofline (PVI+R) (n=13). In the RF group, five patients had PVI only and nine had PVI+R. Substrate ablation was used additionally to PVI with or without roofline ablation in some procedures in both groups (Cryo: n=2; RF: n=4). The total procedure time was significantly shorter with cryoablation compared to RF ablation of persistent AF (Cryo: 146 versus RF: 286 minutes; p<0.0001). There was no difference in the total fluoroscopy time (Cryo: 31.4 ± 17.8 versus RF: 36.1 ± 18.7 minutes; p=0.38). No procedural complications were observed with either Cryo or RF ablation of persistent AF. There was no difference in the recurrence of AF or atrial flutter (AFL) after the blanking period of 90 days (no arrhythmias: 63.6% Cryo versus 84.2% RF; AF: 27.3% Cryo versus 10.5% RF; AFL: 9.1% Cryo versus 5.3% RF; p=0.32). There was no difference in symptom improvement between the 2 groups (no change: 37.9% Cryo versus 15.8% RF; symptoms improved: 51.7% Cryo versus 78.9%; symptoms worsened: 0% Cryo versus 5.3% RF). In terms of the choice of ablation strategy in cryoablation for persistent AF, PVI only strategy significantly shortened both the procedure time and fluoroscopy time compared to PVI+R and additional substrate ablation (procedure time: PVI: 130.7 ± 40.8; PVI+R: 163.8 ± 42.5; substrate: 423.5 ± 3.5 minutes, p<0.0001; fluoroscopy time: PVI: 22.8 ± 16.2; PVI+R: 38.2 ± 16.3; substrate: 46.4 ± 15.6 minutes; p=0.032 ANOVA), without any impact on recurrence of atrial arrhythmias after the blanking period (p=0.55) or symptom improvement (p=0.21).
Conclusion: Cryoablation has comparable efficacy to RF in catheter ablation of persistent AF in the rate of arrhythmia recurrence and symptom improvement, with the added potential advantage of cryoablation significantly reducing the total procedure time. “PVI only” ablation strategy potentially offers similar efficacy to additional ablation of roofline or other substrate in patients undergoing cryoablation for persistent AF, whilst significantly reducing procedure and fluoroscopy time. These findings warrant further study.