AF ablation in end stage heart failure: CASTLE-HTx

By Dr Jonathan Shurlock
Edited by Dr Ahmed El-Medany

Management of symptomatic atrial fibrillation (AF) can be a challenging scenario, often with limited options for adjustment of medication. The CASTLE-HTx investigators explored this topic in a small randomised, open label trial.

As always the key to interpreting the results is in the study design. The previously published CASTLE-HTx protocol describes how patients were recruited from those with end stage heart failure, presenting for heart failure assessment. Interestingly AF could be documented through any form, including cardiac device detected AF. The authors used computed block randomisation.

194 patients were randomised to receive either AF catheter ablation with medical therapy (n=97, age 62±12, 88% male) or guideline directed medical therapy alone (n=97, age 65±10, 74% male). The primary endpoint was a composite outcome composed of death, implantation of a left ventricular assist device, and urgent heart transplantation.

Catheter ablation was performed in 84% of the ablation group and 16% of the medical-therapy group, and intention to treat analysis was carried out. At a median follow-up of 18 months, the composite outcome occurred at a significantly lower rate in the ablation group, compared with the medical therapy group (8% versus 30%, HR 0.24; 95% CI, 0.11 to 0.52; p<0.001). Within this study AF ablation was associated with a lower risk of death from any cause (6% versus 20%).

The study was initially planned for 3 years follow-up, but early termination was recommended by the safety monitoring board due to the large benefit seen from ablation. A key point of discussion has been both the size and timeline of survival benefits seen. Early separation of the Kaplan-Meier survival curves is interesting in the context of previous AF ablation and heart failure trials, which show a survival benefit over years rather than weeks. In addition, while the study purports to explore end-stage heart failure patients, around a third of each group was graded as NYHA II, which questions the applicability of these findings across heart failure populations. A small study population will also be limited in its generalisabilty to a wider population.

See the full study here: