Recurrence of Atrial Fibrillation After Catheter Ablation or Antiarrhythmic Drug Therapy in the CABANA Trial

Abstract

Background: The CABANA (Catheter Ablation Versus Antiarrhythmic Drug Therapy for Atrial Fibrillation) trial randomized 2,204 patients with atrial fibrillation (AF) to catheter ablation or drug therapy. Analysis by intention-to-treat showed a nonsignificant 14% relative reduction in the primary outcome of death, disabling stroke, serious bleeding, or cardiac arrest.

Objectives: The purpose of this study was to assess recurrence of AF in the CABANA trial.

Methods: The authors prospectively studied CABANA patients using a proprietary electrocardiogram recording monitor for symptom-activated and 24-h AF auto detection. The AF recurrence endpoint was any post-90-day blanking atrial tachyarrhythmias lasting 30 s or longer. Biannual 96-h Holter monitoring was used to assess AF burden. Patients who used the CABANA monitors and provided 90-day post-blanking recordings qualified for this analysis (n = 1,240; 56% of CABANA population). Treatment comparisons were performed using a modified intention-to-treat approach.

Results: Median age of the 1,240 patients was 68 years, 34.4% were women, and AF was paroxysmal in 43.0%. Over 60 months of follow-up, first recurrence of any symptomatic or asymptomatic AF (hazard ratio: 0.52; 95% confidence interval: 0.45 to 0.60; p < 0.001) or first symptomatic-only AF (hazard ratio: 0.49; 95% confidence interval: 0.39 to 0.61; p < 0.001) were both significantly reduced in the catheter ablation group. Baseline Holter AF burden in both treatment groups was 48%. At 12 months, AF burden in ablation patients averaged 6.3%, and in drug-therapy patients, 14.4%. AF burden was significantly less in catheter ablation compared with drug-therapy patients across the 5-year follow-up (p < 0.001). These findings were not sensitive to the baseline pattern of AF.

Conclusions: Catheter ablation was effective in reducing recurrence of any AF by 48% and symptomatic AF by 51% compared with drug therapy over 5 years of follow-up. Furthermore, AF burden was also significantly reduced in catheter ablation patients, regardless of their baseline AF type. (Catheter Ablation vs Anti-arrhythmic Drug Therapy for Atrial Fibrillation Trial [CABANA]; NCT00911508).

Keywords: antiarrhythmic drug therapy; atrial fibrillation; catheter ablation; long-standing persistent atrial fibrillation; paroxysmal atrial fibrillation; persistent atrial fibrillation; pulmonary vein isolation.

Figure 1. Patient Flow in CABANA Recurrent Atrial Fibrillation Analysis.

A) A 90-day blanking period from therapy initiation was used in both randomized treatment groups, during which arrhythmia recurrences were not counted toward the recurrent AF endpoint. 161 patients were excluded as they did not contribute to the post 90-day blanking arrhythmia assessment. B) The CABANA ECG recording monitors were used by the majority of enrollment sites and patients. Patients who were at sites not able to use the CABANA ECG recording monitor, or who declined to use them, were monitored according to their sites’s conventional rhythm recording monitors.

Figure 2:. Freedom From Recurrent Atrial Fibrillation, Atrial Flutter or Atrial Tachycardia by Randomized Therapy in 1240 patients Using the CABANA ECG Recording Monitors Post 90-Day Blanking.

* Figure 2 shows the cumulative incidence of a first occurrence of AF, or the composite of AF, AFL or AT over five years of follow up. Results are shown according to randomized therapy. Cumulative incidence estimates using death as a competing risk were derived using Fine-Gray competing risks methodology. AF=atrial fibrillation; AFL=atrial flutter; AT=atrial tachycardia; CI=Confidence interval; *Patient population shown in Figure 1.

Figure 3. Atrial Fibrillation Burden Post 90-Day Blanking Assessed at Six-Month Intervals in 1240 Patients Using the CABANA ECG Holter Monitors.

* The percentage AF burden is shown according to randomized treatment groups as assessed at each of the 6-month Holter recording time-points. AF=atrial fibrillation. *Patient population shown in Figure 1.

Figure 4:. Atrial Fibrillation Burden According to Baseline Pattern of Atrial Fibrillation, 90-Day Blanking Assessed at Six-Month Intervals in 1240 Patients Using the CABANA ECG Holter Monitors.

*AF burden is shown according to randomized treatment groups as assessed at each of the 6-month Holter recordings. 4A shows AF burden in patients who were considered paroxsymal AF at baseline and 4B shows AF burden for patients considered to have persistent or long-standing persistent AF at baseline. AF=atrial fibrillation.*Patient population shown in Figure 1.

Figure 4:. Atrial Fibrillation Burden According to Baseline Pattern of Atrial Fibrillation, 90-Day Blanking Assessed at Six-Month Intervals in 1240 Patients Using the CABANA ECG Holter Monitors.

*AF burden is shown according to randomized treatment groups as assessed at each of the 6-month Holter recordings. 4A shows AF burden in patients who were considered paroxsymal AF at baseline and 4B shows AF burden for patients considered to have persistent or long-standing persistent AF at baseline. AF=atrial fibrillation.*Patient population shown in Figure 1.

Figure 5:. Use of Antiarrhythmic Drugs Among Subjects Without AF Recurrence Post 90-Day Blanking Assessed at Six-Month Intervals in 1240 Patients Using the CABANA ECG Holter Monitors.

* The percentage of patients without an AF episode lasting 30 seconds or more in duration captured at any time during the scheduled 6-month Holter recordings is shown in this graph. Results are displayed according to randomized therapy. The insets within the bars shows the proportion of patients taking or not taking an antiarrythmic drug at the time of Holter acquisition. The cross hatching within the randomized drug therapy arm shows the percentage of patients who were not taking an antiarrhythmic drug and had crossed over from drug therapy to ablation therapy prior to Holter acquistion at that 6 month timepoint. AF=atrial fibrillation; AAD=antiarrhythmic drug. *Patient population shown in Figure 1.

Central Illustration:. 1240 Patients Using the CABANA ECG Recording Monitors Post 90-Day Blanking.

* Monitoring for recurrent atrial tachyarrhythmias used a CABANA specific ECG monitor, which included finger-tip symptom-driven TTM monitoring. Additionally, 24 hour continuous TTM loop recordings with AF auto-detection were obtained monthly in the first year of follow-up and then quarterly thereafter. Cumulative incidence of first symptomatic AF episode and cumulative incidence of first symptomatic or asymptomatic AF, is shown as, freedom from recurrence over five years following the 90-day blanking period post randomized therapy (both ablation and drug therapy). Cumulative incidence estimates using death as a competing risk were derived using Fine-Gray competing risks methodology. CI=Confidence interval; TTM= transtelephonic monitoring; symp=symptomatic. *Patients who did not receive randomized therapy, did not use the CABANA ECG recording system, or for any other reason, did not provide post 90-day blanking recordings (Figure 1) are not included in this analysis.