CASTLE-AF: Catheter Ablation vs. Conventional Therapy For Patients With AFib and LV Dysfunction

Catheter ablation improved outcomes for patients with atrial fibrillation (AFib) and left ventricular dysfunction, compared to conventional drug treatment, based on results from the CASTLE-AF trial presented on Aug. 27 at the ESC Congress 2017 in Barcelona.

The trial included 397 patients with symptomatic paroxysmal or persistent AFib and a left ventricular ejection fraction (LVEF) of ≤35 percent who were randomized to receive either radiofrequency catheter ablation or conventional drug treatment. All patients had an implantable cardioverter defibrillator with Home Monitoring capability. The primary endpoint was the composite of all-cause mortality and unplanned hospitalization for worsening heart failure.

Results showed the primary endpoint was significantly lower in the ablation group (28.5 percent) compared to the control group (44.6 percent) over a median follow-up period of 37.8 months. Secondary endpoints of all-cause mortality and heart failure hospitalization were also significantly lower in the catheter ablation group, compared to the conventional treatment group (13.4 percent vs. 25 percent and 20.7 percent vs. 35.9 percent, respectively).

Nassir F. Marrouche, MD, principal investigator for CASTLE-AF, noted that despite some limitations the trial “sheds light on the importance of restoring and maintaining regular heart rhythm with ablation” and could have a “major impact” on reducing costs associated with hospitalizations.

A complimentary study published in the Journal of the American College of Cardiology, suggests catheter ablation for AFib could improve left ventricular systolic dysfunction (LVSD) compared to medical rate control in patients where the etiology of LVSD is unexplained apart from the presence of AFib itself. The CAMERA-MRI study randomized 68 patients with persistent AFib and idiopathic cardiomyopathy (LVEF ≤45 percent) to receive either catheter ablation or ongoing medical rate control. AFib burden was assessed following catheter ablation using an implanted loop recorder, while medical rate control was assessed with serial Holter-monitoring.

Results showed the average AFib burden following catheter ablation was 1.6 percent ± 5.0 percent at six months. On intention to treat analysis, absolute LVEF improved by +18 ± 13 percent in the catheter ablation group compared to +4.4 ± 13 percent in the medical rate control group, (p<0.0001) and normalized. In the patient undergoing catheter ablation, researchers noted that the absence of LGE predicted greater improvements in absolute LVEF (p = 0.0069) and normalization at six months (73 percent vs. 29 percent, p = 0.0093).

“The restoration of sinus rhythm with catheter ablation results in significant improvements in ventricular function, particularly in the absence of ventricular fibrosis on cardiac MR,” researchers wrote. “This challenges the current treatment paradigm that rate control is the appropriate strategy in patients with AFib and LVSD.”

In a related editorial comment, Oussama M. Wazni, MD, FACC, and Mina K. Chung, MD, FACC, note the limitations of the study, including its small size, no data on hospitalizations or mortality, and a complication rate that was much lower than that reported by very experienced operators. “Nevertheless, taken together with the results of the recent ablation vs. medical therapy studies in heart failure in which ablation was associated with better outcomes, the positive results of this study should encourage the rethinking of current guidelines, especially in heart failure patients in whom durable sinus rhythm with minimal use of antiarrhythmic drugs achieved through catheter ablation may be a matter of life and death,” they write. 

Keywords: ESC Congress, ESC2017, Catheter Ablation, Anti-Arrhythmia Agents, Atrial Fibrillation, Electrocardiography, Ambulatory, Defibrillators, Implantable, Intention to Treat Analysis, Ventricular Dysfunction, Left, Heart Failure, Heart Ventricles, Cardiomyopathies, Ventricular Function, Hospitalization, Magnetic Resonance Imaging

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