The results of the CASTLE-AF study, published today in the New England Journal of Medicine, show that patients treated with radiofrequency catheter ablation rather than traditional drug therapies for atrial fibrillation had improved outcomes.
“This clinical trial is the first time we can show with hard data that ablation is saving more lives than arrhythmia medications,” said Nassir F. Marrouche, lead author, professor in Internal Medicine and executive director of the Comprehensive Arrhythmia Research and Management (CARMA) Center at University of Utah Health. “It also lowers the cost of treating patients by keeping them out of hospital due to lower incidence of worsening heart failure.”
Marrouche and colleagues from the University of Utah, USA and Klinikum Coburg, Germany conducted the eight-year CASTLE-AF clinical trial from 2008–16, with the aim of comparing the outcomes of catheter ablation to the conventional drug therapies recommended by the American Heart Association and European Heart Society to control the heart’s rate.
Patients from North America, Europe and Australia with heart failure and a history of symptomatic atrial fibrillation were screened for the study. The research team selected 363 participants, characterised by heart function at less than 35% capacity, for the clinical trial. The patients were separated into two groups, receiving either radiofrequency catheter ablation (179) or a conventional drug therapy (184).
After a median follow-up of 37.8 months, the primary composite end point occurred in significantly fewer patients in the ablation group than in the medical therapy group (51 patients [28.5%] vs. 82 patients [44.6%]; hazard ratio, 0.62; 95% confidence interval [CI], 0.43 to 0.87; P = 0.007). Significantly fewer patients in the ablation group died from any cause (24 [13.4%] vs. 46 [25.0%]; hazard ratio, 0.53; 95% CI, 0.32 to 0.86; P = 0.01), were hospitalized for worsening heart failure (37 [20.7%] vs. 66 [35.9%]; hazard ratio, 0.56; 95% CI, 0.37 to 0.83; P = 0.004), or died from cardiovascular causes (20 [11.2%] vs. 41 [22.3%]; hazard ratio, 0.49; 95% CI, 0.29 to 0.84; P = 0.009).
All of the participants included in the CASTLE-AF trial had previously received an implantable cardioverter defibrillator (ICD), which allowed for continuous monitoring of heart rate. The ICD may have improved outcomes. Marrouche believes this is the primary limitation in the study and may have affected death rates in both groups.
The results were previously presented at the European Society of Cardiology (ESC) congress(26–30 August 2017, Barcelona, Spain).