Catheter ablation safe, effective for AF in patients awaiting heart transplant
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Key takeaways:
- Catheter ablation was safe and effective vs. medical therapy alone in patients with atrial fibrillation and end-stage heart failure.
- Ablation was tied to improved LV function and reduced arrhythmia burden.
In patients with end-stage HF awaiting transplant, catheter ablation for atrial fibrillation was safe and effective and was associated with improvements in left ventricular ejection fraction and AF burden, a speaker reported.
The duration of follow-up was intended to be 3 years, but due to the number of clinical events, the trial data safety monitoring board recommended to stop the study prematurely at 1.5 years.
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The results of the CASTLE-HTx trial were presented at the European Society of Cardiology Congress and simultaneously published in The New England Journal of Medicine.
In the original CASTLE-AF trial, researchers enrolled 397 patients with symptomatic persistent or paroxysmal AF who failed or were intolerant of at least one antiarrhythmic drug and had LVEF of 35% or less and were assigned to radiofrequency catheter ablation or medical therapy.
As Healio previously reported, catheter ablation was associated with improved outcomes, including reduced all-cause mortality and fewer HF hospitalization, compared with medical therapy.
“The clinical question that we had in our daily routine was can this knowledge and these data be transferred also to patients that are in an even more advanced stage of their HF,” Philipp Sommer, MD, FHRS, FESC, FEHRA, professor of cardiology at the Heart and Diabetes Center North Rhine-Westphalia, University of Bochum in Bad Oeynhausen, Germany, said during a press conference. “[CASTLE-HTx is] a single-center study, which is kind of unusual for a study like that. CASTLE-AF recruited their patients in about 35 centers. We have a pretty big center in a pretty small place, but our heart center did perform about 3,000 heart transplants in the last 30 years ... and you can imagine that a lot of patients from all over the country are referred to our institution to be validated for eligibility for undergoing a transplant. Also, we have a huge [left ventricular assist device] program ... with about 75 to 95 LVAD implants per year.”
Sommer and colleagues conducted the single-center, open-label CASTLE-HTx trial to evaluate the feasibility and benefits of AF ablation plus medical therapy compared with medical therapy alone in 194 patients with end-stage HF. The median LVEF was approximately 29% and the majority of patients were NYHA class III or IV, according to the presentation.
The primary endpoint was a composite of all-cause death, LVAD implantation or urgent heart transplantation. The secondary endpoint was all-cause death.
Sommer reported that AF ablation conferred a 76% lower risk for the primary composite endpoint (HR = 0.24; 95% CI, 0.11-0.52; P < .001) and a large reduction in all-cause mortality (HR = 0.29; 95% CI, 0.12-0.72; P < .005) compared with medical therapy in patients with AF and end-stage HF.
Moreover, they observed an average increase of 8% in LVEF and a reduction in AF burden of approximately 50% in the ablation arm compared with the medical therapy arm.
“AF ablation is safe and effective in patients with end stage heart-failure,” Sommer said during the press conference. “AF ablation, in our eyes, should be considered as part of standard treatment options in advanced heart failure patients besides drug therapies, and this should be part of our armamentarium of treating those patients. AF ablation has beneficial effects on mortality during the so-called ‘waiting time’ for patients planning to undergo a transplant and prolongs the time span until surgical interventions will be necessary.”
Reference:
Perspective
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Luigi Di Biase, MD, PhD, FACC, FHRS
What we know is that catheter ablation plus medication in patients with HF is superior for multiple outcomes, including mortality, rehospitalization and freedom from AF. This has been demonstrated in many randomized control trials and many smaller nonrandomized trials, but all of these trials enrolled patients that were not end-stage. They were not as sick as the patients in CASTLE-HTx, but nonetheless in CASTLE-HTx the outcome favored ablation in a very important way when looking at mortality, and the trial was stopped early for efficacy.
It's a very difficult population to study. The number of patients that have been analyzed is not big. They are less than 100 per group. Although a statistical significance was there and although the study was prematurely stopped, we don’t have enough power in terms of statistics. All we know is that it looks like that with current technology, ablation does better. Because of that, we should think more about ablation in this population because it may be a way to buy time before the heart transplant and probably before a left ventricular assist device implant. These are two very important socioeconomic repercussions. These are things that really matter for the patient and should be taken in strong consideration.
We need more data, but many people with end-stage HF will now consider ablation. The problem is whether the patient can undergo an ablation. Is the patient able to lie flat for a couple of hours on the table? These are important things that we need to consider. But, for those patients that can do that, ablation represents an important treatment option.
The most recent guidelines on HF and ablation have considered ablation as class IIa and amiodarone as class I for any type of patient with HF and low EF. The guidelines should be revisited to increase the level of indication for ablation, or at least reduce the indication for amiodarone to a lower class than class I. Amiodarone is a drug with a lot of side effects that might increase mortality.
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Sommer P. Hot Line 6. Presented at: European Society of Cardiology Congress; Aug. 25-28, 2023; Amsterdam (hybrid meeting).
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