Ablation Cuts A-fib Recurrences, Burden Through 5 Years in CABANA

Catheter ablation suppresses A-fib recurrences and reduces the overall arrhythmic burden relative to drug therapy through 5 years of follow-up in patients with symptomatic A-fib, additional data from the CABANA trial show.

The overall 2,204-patient trial failed to show that catheter ablation reduced the primary composite endpoint of death, disabling stroke, serious bleeding, or cardiac arrest, but it did demonstrate a 48% relative reduction in A-fib recurrence, a secondary endpoint, after ablation through 4 years of follow-up.

In this new analysis with follow-up out to 5 years, roughly the same relative reduction was seen for the first recurrence of any symptomatic or asymptomatic episodes lasting 30 seconds or more (48%), of symptomatic A-fib alone (51%), and of any atrial fibrillation, flutter, or tachycardia (47%) after ablation.

Investigators led by Jeanne Poole, MD (University of Washington Medical Center, Seattle), also assessed A-fib burden based on the proportion of time patients were in A-fib during Holter monitoring—this was 48% in both groups at baseline. Burden declined in both the ablation and drug-therapy arms of the trial, but it remained lower after ablation at both 1 year (6.3% vs 14.4%) and 5 years (14.7% vs 20.8%).

Poole told TCTMD that these findings, published online ahead of the June 30, 2020, issue of the Journal of the American College of Cardiology, bolster the main trial findings and that together they “strongly support catheter ablation as a very important therapy for patients with atrial fibrillation.”

Declines in Antiarrhythmic Drug Use

This analysis expands on the A-fib recurrence data from the main trial publication by lengthening the duration of follow-up and focusing on the 1,240 trial participants (56% of the total) who were prospectively evaluated using proprietary CABANA ECG recording monitors (Medicomp); mean age of the patients was 68 years, 34.4% were women, and 43.0% had paroxysmal A-fib. Recurrence was defined as any atrial tachyarrhythmias lasting at least 30 seconds that occurred after the 90-day blanking period. Every 6 months, 96-hour Holter monitoring was performed to evaluate A-fib burden.

By 12 months, 12.6% of patients in the ablation arm and 27.5% of those in the drug arm had a recurrence of symptomatic A-fib, and 36.4% and 59.2%, respectively, had a first recurrence of any A-fib.

Through 5 years, catheter ablation was associated with reductions in first recurrences of:

• Any symptomatic or asymptomatic A-fib (HR 0.52; 95% CI 0.45-0.60)
• Symptomatic A-fib (HR 0.49; 95% CI 0.39-0.61)
• Any atrial fibrillation, flutter, or tachycardia (HR 0.53; 95% CI 0.45-0.62)

The authors note that “occurrence of atrial flutter or atrial tachycardia as the initial recurrent posttreatment arrhythmia contributed little to first recurrent atrial tachyarrhythmias.”

Results were similar in as-treated and per-protocol analyses. Looking at A-fib burden, the advantage for catheter ablation remained regardless of the pattern of A-fib at baseline (paroxysmal, persistent, or long-standing persistent).

In addition, use of antiarrhythmic drugs was lower in the ablation arm over the 5-year follow-up period—the proportion of patients receiving them was 10% to 20%, whereas use declined to 33% among those in the drug-therapy arm. That “appears to have been largely affected by patient crossovers to ablation therapy,” the authors say.

Linking Clinical Outcomes and A-fib Recurrences

Commenting for TCTMD, Cynthia Tracy, MD (George Washington University School of Medicine & Health Sciences, Washington, DC), said this analysis is useful in that it expands on what has been reported from the CABANA trial so far. Interpretation of these data is complicated by the same issues that were brought up when the main trial results were presented, she said—namely, the frequent crossovers between arms.

But “taken at face value,” Tracy said, “this does seem to show that ablation has a durable benefit and it does seem to show that that benefit is present both for paroxysmal and for persistent atrial fibrillation, so that’s useful information.”

She said a big piece that’s missing, one also pointed out in an accompanying editorial by Francis Marchlinski, MD (Hospital of the University of Pennsylvania, Philadelphia), and colleagues, is an analysis linking the reduction in A-fib recurrences with improvements in symptoms and quality of life.

“I would have liked to see some correlation with symptoms, and I think that—hopefully—will be the next publication that will come out of the CABANA study,” Tracy said.

Poole noted that the positive impact of catheter ablation on quality of life in the CABANA trial has already been reported, acknowledging that those gains have not been directly tied to a reduction in recurrences. “But given the fact that quality of life . . . was significantly improved in patients who were randomized to the catheter ablation group, it is reasonable to assume that when that linking study can be performed that we will identify that improvement in quality of life was also related to a reduction in first recurrence or in atrial fibrillation burden,” she said.

In their editorial, Marchlinski et al say: “We believe including this important information could have strengthened the presentation and emphasized its potential immediate clinical relevance. Such data reporting would have been valuable even if direct symptom and Holter atrial fibrillation burden correlation was not systematically available by study design.”

For now, Tracy said, these expanded ECG data likely will not have an impact on how ablation is used in current practice.

“We know that ablation for A-fib is not perfect,” she said. “This reiterates that there is a fairly high recurrence rate regardless of whether you’re treating with ablation or medication. We know that A-fib is a moving target and that we have to continue managing these patients over time. I don’t see this as something that’s going to change how we manage A-fib patients. I see it as sort of a call for us to get a better concept of exactly what is the burden threshold at which we do something for recurrent atrial fibrillation. It maybe is pushing us to get a little bit more strict in terms of how we define recurrence and what we do with those recurrences.”

And incorporating A-fib burden into the discussion, Poole said, “allows clinicians and investigators to think about what is the meaningful outcome of catheter ablation, or drug therapy for that matter. And it would foster hopefully some further opportunities to define what AF burden really is and how it should be measured.”