Outcomes of cryoballoon or radiofrequency ablation in symptomatic paroxysmal or persistent atrial fibrillation

Abstract

Aims: To evaluate the effectiveness and safety of cryoballoon ablation (CBA) compared with radiofrequency ablation (RFA) for symptomatic paroxysmal or drug-refractory persistent atrial fibrillation (AF).

Methods and results: Prospective cluster cohort study in experienced CBA and RFA centres. Primary endpoint was 'atrial arrhythmia recurrence', secondary endpoints were as follows: procedural results, safety, and clinical course. A total of 4189 patients were included: CBA 2329 (55.6%) and RFA 1860 (44.4%). Cryoballoon ablation population was younger, with fewer comorbidities. Procedure time was longer in the RFA group (P = 0.01). Radiation exposure was 2487 (CBA) and 1792 cGycm2 (RFA) (P < 0.001). Follow-up duration was 441 (CBA) and 511 days (RFA) (P < 0.0001). Primary endpoint occurred in 30.7% (CBA) and 39.4% patients (RFA) [adjusted hazard ratio (adjHR) 0.85, 95% confidence interval (CI) 0.70-1.04; P = 0.12). In paroxysmal AF, CBA resulted in a lower risk of recurrence (adjHR 0.80, 95% CI 0.64-0.99; P = 0.047). In persistent AF, the primary outcome was not different between groups. Major adverse cardiovascular and cerebrovascular event rates were 1.0% (CBA) and 2.8% (RFA) (adjHR 0.53, 95% CI 0.26-1.10; P = 0.088). Re-ablations (adjHR 0.46, 95% CI 0.34-0.61; P < 0.0001) and adverse events during follow-up (adjHR 0.64, 95% CI 0.48-0.88; P = 0.005) were less common after CBA. Higher rehospitalization rates with RFA were caused by re-ablations.

Conclusions: The primary endpoint did not differ between CBA and RFA. Cryoballoon ablation was completed rapidly; the radiation exposure was greater. Rehospitalization due to re-ablations and adverse events during follow-up were observed significantly less frequently after CBA than after RFA. Subgroup analysis suggested a lower risk of recurrence after CBA in paroxysmal AF.

Trial registration: ClinicalTrials.gov (NCT01360008), https://clinicaltrials.gov/ct2/show/NCT01360008.

Keywords: Atrial fibrillation; Catheter ablation; Cryoballoon; Paroxysmal; Persistent; Radiofrequency.

Figure 1

Study population. This flow chart depicts the trial design and provides details on centres, clusters, and groups. Within the cluster cohort trial, 42 experienced centres were enrolled in two clusters: CBA and RFA. Those clusters treated 2329 and 1860 patients with CBA and RFA, respectively. The crossover rate to any other technique was very low in both groups. CBA, cryoballoon ablation; FU, follow-up; RFA, radiofrequency ablation.

Figure 2

Comparison of the main adjusted effectiveness and safety outcome parameters of the total population and paroxysmal and persistent AF. The adjusted hazard ratios of the multivariable models with confidence intervals and the P-values for CBA vs. RFA after a single procedure are provided for the major long-term outcome. (A) Depicts the results of the total population; in (B) and (C), the outcomes of the AF-type subgroups are presented. See Supplementary material online, Table S4 for details of the adjustments performed. Level of statistical significance was set at P < 0.05. *‘Centre’ as a random effect was not applicable in the multivariable model. AF, atrial fibrillation; AT, atrial tachycardia; CI, confidence interval; HR, hazard ratio; MACCE, major adverse cardiovascular and cerebrovascular event.

Figure 3

Comparison of the EHRA symptom scores at baseline and follow-up in the CBA and RFA groups. This 100% stacked column chart depicts the differences in the EHRA symptom score distribution at baseline and follow-up in the CBA and RFA groups. Results are displayed as the percentage of patients. In both groups, a significant improvement was observed with P < 0.001. In the RFA group, patients more frequently demonstrated an EHRA score of 3 or 4 at baseline as compared to the CBA group (80.1% vs. 47%, P < 0.001), and an EHRA score of 2 was more often documented in the CBA group. Improvement in the EHRA score of at least one class was observed in 76.3% and 84.9% of the patients in the CBA and RFA groups, respectively (P < 0.0001). More patients in the CBA group demonstrated an EHRA score of 1 (no symptoms) at follow-up (75.5% vs. 70.5%, P < 0.01). CBA, cryoballoon ablation; EHRA, European Heart Rhythm Association; RFA, radiofrequency ablation.

Figure 4

Adjusted Kaplan–Meier curve for ‘Total MACCEs’ with CBA vs. RFA. Adjusted Kaplan–Meier curves for total MACCEs were calculated for a standard patient using the Breslow method. After adjustment, a non-significant trend towards a lower MACCE rate in the CBA group (adjusted HR 0.53, 95% CI 0.26–1.10; P = 0.088) was observed. Level of statistical significance was set at P < 0.05. CBA, cryoballoon ablation; CI, confidence interval; EHRA, European Heart Rhythm Association; HR, hazard ratio; MACCE, major adverse cardiovascular and cerebrovascular event; PAF, paroxysmal atrial fibrillation; RFA, radiofrequency ablation.