ABC | Volume 110, Nº4, April 2018

Editorial Catheter Ablation for Atrial Fibrillation in Patients with Heart Failure Mauricio Scanavacca and Edimar Alcides Bocchi Instituto do Coração (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP - Brazil Mailing Address: Mauricio Scanavacca • Unidade de Arritmias Cardíacas do Incor-HC-FMUSP AV. Dr Eneas de Carvalho Aguiar, 44, Postal code: CEP: 05403-000; São Paulo, Brazil E-mail: mauricio.scanavacca@gmail.com Keywords Heart Failure; Atrial Fibrillation; Catheter Ablation / trends; Atrial Remodeling; Amiodarone DOI: 10.5935/abc.20180066 In the last years, atrial fibrillation (AF) and heart failure (HF) have been the two major epidemic syndromes in cardiology and they frequently coexist. 1 HF increases mean right and left atria pressures promoting their progressive dilation. Such mechanical electro-anatomic remodeling predisposes to atrial fibrosis and electrical heterogeneity, increases ectopic rhythm formation and ultimately induces AF. 2 A new AF episode, in turn, immediately induces loss of atrial contraction, increases mean heart rate and provokes an important irregularity on ventricular contractions decreasing the heart’s pump function performance. Therefore, around 50% of patients who present with new-onset congestive HF have atrial fibrillation and up to one-third of patients with new-onset AF have congestive heart failure. 2 The Framingham study demonstrated that in AF patients, occurrence of HF was associated with significant increase in mortality, as well as in HF patients, a new AF development was associated with significant rise on mortality. 3 Therefore, there is a biological rationale for the prevention and treatment of AF associated with HF. The targets would be ventricular control, especially rhythm control. Several pharmacological studies have failed to demonstrate clinical benefits in maintaining sinus rhythm compared to rate control in patients with normal or abnormal left ventricle function. 4-6 In the AFFIRM trial, the management of atrial fibrillation with rhythm-control strategy offered no survival advantage over the rate-control strategy, and patients had higher rate of hospitalization. The potential explanation for that was the antiarrhythmic drugs’ adverse effects. 4 In patients with left ventricle dysfunction, the use of antiarrhythmic drugs safely recommended for this condition, such as dofetilide and amiodarone, also did not show any hard endpoint benefits. 5,6 Catheter ablation for AF has emerged as the most effective strategy to maintain the sinus rhythm in patients with paroxysmal and persistent AF and has been used worldwide. 7,8 However, there is a paucity of studies investigating hard endpoints as mortality reduction in patients with HF with catheter ablation. The study “A randomized controlled trial of catheter ablation versus medical treatment of atrial fibrillation in heart failure (the CAMTAF trial)“ was able to demonstrate an improvement in left ventricular ejection fraction (LVEF) with ablation in patients with persistent AF. 9 Additional advantages were observed in the “Ablation versus Amiodarone for Treatment of Atrial Fibrillation in Patients with Congestive Heart Failure and an Implanted ICD (The AATAC) trial”. Di Biase et al 10 showed that ablation was superior to amiodarone in maintaining sinus rhythm, improving LVEF, improving survival rates and decreasing hospitalization for HF. More recently, an additional enthusiasm comes up with the report of “Catheter ablation for atrial fibrillation with heart failure (Castle-AF) trial”. Marrouche et al confirmed observations of the AATAC trial, showing that catheter ablation of AF significantly reduces mortality in patients with HF, as compared with medical therapy. 11 CASTLE-AF is a multicenter study, conducted from January 2008 through January 2016, and involving a total 33 sites in Europe, Australia, and the United States. In this study, 263 patients with symptomatic paroxysmal or persistent AF were randomly assigned to undergo AF catheter ablation (179) or medical treatment (184), using rate or rhythm control strategies. All the patients had New York Heart Association (NYHA) class II, III, or IV HF, a LVEF of 35% or less, and an implanted defibrillator. The primary end point was notably hard, a composite of death from any cause and hospitalization for worsening HF. The final results were obtained after a median follow-up of 37.8 months and favored catheter ablation comparing to medical therapy. In the ablation group, 63% of patients were in sinus rhythm at 60 months versus 22% in the medical-therapy group. The primary composite end point occurred in 51 (28.5%) patients in the ablation group and in 82 (44.6%) patients in the medical therapy group (HR = 0.62; P = 0.007). There was a significant reduction of all-cause mortality in the ablation group (13.4% vs. 25.0%), HR = 0.53, P = 0.01 and from cardiovascular causes (11.2% vs. 22.3%); HR = 0.49; P = 0.009. Additionally, patients undergoing catheter ablation showed reduced hospitalization rate in consequence of worsening heart failure (20.7%) comparing to medical treatment (35.9%), HR = 0.56, P = 0.004. Furthermore, catheter ablation reduced the burden of AF, increased the distance walked in 6 minutes, and improved the LVEF (8%). An important detail from this study was the observation that the mortality benefit of ablation emerged just after 3 years of follow-up. These observations are unique since it is the first trial on catheter ablation field designed to show both, superiority in maintaining the sinus rhythm and mortality reduction comparing to medical therapy. However, CASTLE-AF trial has some important limitations as highly patient selection – from 3,013 patients assessed for eligibility, just 263 were finally included in the primary analysis. Investigators were not blinded treatment randomization, and a number of patients crossed over to the other treatment group. Additionally, the procedures were performed in high-volume medical centers 300