Background:

In selected symptomatic patients with reduced left ventricular ejection fraction (LVEF) and atrial fibrillation (AF), ablation has been proposed for rhythm control. It is unclear, if Cryoballoon Ablation (CBA) or Radiofrequency (RFA) is the preferred technique in the initial ablation procedure.  

Methods:

The FREEZE Cohort (NCT01360008) evaluated the effectiveness and safety of CBA compared with RFA for symptomatic paroxysmal or drug-refractory persistent atrial fibrillation. Primary endpoint was “atrial arrhythmia recurrence”, secondary endpoints were procedural results, safety, and clinical course. This sub-analysis included patients with LVEF <50% at baseline.

Results:

From 2011 to 2016, a total of 4,189 patients were enrolled, and 256 (6.1%) patients (118 CBA,138 RFA) qualified for the sub-analysis. Mean age was 63.4±9.9 years, and 60.9% suffered from persistent AF. Mean LVEF was 42.0% (p=0.81), and the percentage of patients with LVEF ≤40% was 47.7%. The median LA diameter was 47.0 mm, and the percentage of pts. with LA >45 mm was 58.2%. 

CHA₂DS₂-VASc Score was lower in the CBA group (2.3 vs. 2.8, p<0.01). 

The mean procedure time (141 vs. 164 min.), LA time (100 vs. 128 min.), and the total duration of applications (36 vs. 49 min.) were shorter in the CBA group (for all p<0.001). Mean fluoroscopy time (27 vs. 22 min., p<0.001)) and median dose area product (2878 vs. 2097 cGyxcm2, p<0.01) were higher in the CBA group. 

Acute PVI was achieved in 96.4% of patients (p=0.57). Additional linear lesions were performed more frequently in the RFA group (11.2% vs. 22.2%, p<0.05). Procedural complications were observed in 5.1% in the CBA and 13.1% in the RFA group (p<0.05). No differences were found for major adverse events including tamponade, and phrenic nerve palsy. Arrhythmia relapse until discharge was more often documented in the RFA group (6.8% vs. 15.4%, p<0.05).

After a follow-up of 449 and 516 days (p<0.001), no significant differences between CBA and RFA groups were observed for arrhythmia recurrence (51.2 vs. 58.7%, p=0.30), EHRA score III/IV (7.2% vs. 6.9%, p=0.93), cardioversion (16.1% vs. 17.2%, p=0.84), and total MACCE rate (3.4 vs. 9.2%, p=0.11), respectively. Repeat ablations were performed in 11.5% (CBA) and 22.1% (RFA) of patients (p=0.06). Rehospitalization following ablation occurred more frequently in the RFA group (34.9% vs. 52.1%, p<0.05). Patients rated the procedure as “overall successful” in 48.2% (p=0.99), and “feeling safe during treatment” in 92.9% (p=0.75). The majority would return to the same institution if necessary (94.1%, p=0.68). 

Conclusion

Persistent AF was the dominant type of AF in patients with reduced LVEF undergoing AF ablation. Acute PVI was achieved in an equally high percentage of patients with either CBA or RFA. However, procedures were longer and more complex in the RFA group, whereas fluoroscopy time and dose area product were higher in the CBA group. Minor procedural complications occurred more frequently in the RFA group. 

At follow-up, no differences were observed between the groups for atrial arrhythmia recurrence, cardioversion, and adverse event rates. Rehospitalizations were documented more frequently following RFA, including a trend for more repeat ablations. 

Overall, this study suggests that AF catheter ablation in patients with reduced LVEF is safe and effective with either CBA or RFA.