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CASTLE-AF: Ablation reduces AF burden in HF

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BOSTON — Catheter ablation improved atrial fibrillation burden and time to first AF recurrence in patients with AF and HF, according to new data from the CASTLE-AF trial.

As Cardiology Today previously reported, in the main findings of CASTLE-AF — a trial of 397 patients with symptomatic persistent or paroxysmal AF and left ventricular ejection fraction of 35% or less who failed or were intolerant of at least one antiarrhythmic drug or were unwilling to take the medication — those assigned catheter ablation had a lower rate of all-cause mortality and hospital admissions for worsening HF than those assigned conventional drug treatment.

For the present analysis, presented at the Heart Rhythm Society Annual Scientific Sessions, the researchers evaluated the effect of ablation on AF burden and AF recurrence, and whether those factors had any effect on clinical outcomes on the as-treated population of CASTLE-AF participants (ablation group, n = 150; mean age, 63 years; 89% men; medical therapy group, n = 210; mean age, 64 years; 83% men).

“CASTLE-AF was the first trial that prospectively demonstrated that catheter ablation of patients with heart failure improved the hard clinical endpoints of hospitalization for heart failure and mortality,” Johannes Brachmann, MD, from the department of cardiology, Hospital Klinikum Coburg, Teaching Hospital of the University of Würzburg, Coburg, Germany, said during a presentation. “It was our interest to look at the post hoc analysis of whether there is an association between AF recurrence and clinical outcomes, whether we can predict long-term outcomes based on AF burden after ablation and whether reduction in AF burden plays a role in clinical outcome.”

AF burden was defined as time in AF per day. Time to first AF recurrence was defined as time to the first day with AF burden greater than 5%.

In the overall cohort, compared with those with AF burden of 5% or less, those with AF burden greater than 5% up to 80% (OR = 3.34; 95% CI, 1.5-7.46) and those with AF burden greater than 80% (OR = 2.51; 95% CI, 1.22-5.66) had greater odds of all-cause mortality or HF hospitalization at 1 year. At 2 years, results were similar for those with AF burden greater than 5% up to 80% but no longer significant in those with AF burden greater than 80%.

Long-term AF burden was reduced by ablation (area under the curve = 0.66; P = .012), but not by conventional medical therapy, Brachmann said.

Time to first AF recurrence was longer in the ablation group vs. the medical therapy group at 5 years regardless of whether a blanking period was used (P < .0001 for both), but AF recurrence did not affect risk for all-cause mortality or HF hospitalization, he said.

In those who underwent ablation, AF burden greater than 80% predicted increased risk for all-cause mortality or HF hospitalization at 10 and 180 days without a blanking period, but not at 30, 90 or 180 days after a blanking period. In those who did not undergo ablation, AF burden was not a predictor of increased risk for all-cause mortality or HF hospitalization.

Among those who had ablation, patients with at least a 50% reduction in AF burden had reduced risk for all-cause mortality or HF hospitalization (HR = 2.33; 95% CI, 1.1-4.94) and all-cause mortality (HR = 3.36; 95% CI, 1.13-10) compared with those who had less than a 50% reduction in AF burden at 180 days without a blanking period, Brachmann said.

At 180 days after a 90-day blanking period, a similar dichotomy was seen between patients with at least a 40% reduction in AF burden vs. those who had less than a 40% reduction, he said.

When the researchers analyzed early change in AF burden in the ablation group, they found that those with an early reduction of at least 30% in AF burden had reduced risk for all-cause mortality or HF hospitalization and all-cause mortality alone at 180 days without a blanking period. At 180 days after a 90-day blanking period, those with an early reduction in AF burden of at least 10% had reduced risk for all-cause mortality or HF hospitalization and those with an early reduction of at least 20% had reduced risk for all-cause mortality.

“In patients suffering from atrial fibrillation and heart failure, atrial fibrillation ablation did improve the AF burden [and] time to first recurrence,” Brachmann said. “Higher AF burden was associated with increased risk for the composite endpoint of mortality and heart failure admissions. The time to first recurrence did not predict the clinical outcome and the relative reduction of AF burden after ablation predicted the composite endpoint and mortality.” – by Erik Swain

Reference:

Brachmann J, et al. LBCT02-04. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 9-12, 2018; Boston.

Disclosure: The study was funded by Biotronik GmbH. Brachmann reports he has financial ties with Bayer, Biotronik, Boehringer Ingelheim, Boston Scientific, Bristol-Myers Squibb/Pfizer, Daiichi Sankyo, Medtronic, Siemens, Sorin and St. Jude Medical.