The results reported in this study indicate that AF ablation in HF patients with reduced or preserved LVEF is a safe and acceptable therapeutic option. The acute success rate was high, 90% after the procedure, and although 47 patients had arrhythmia recurrence, a second procedure was successful in maintaining SR at one year in 72.2% of the cases, without increasing the incidence of complications. The improvement of symptoms and the hospitalization rate showed that SR maintenance had significant benefits in these patients. Of the variables analyzed, persistent AF before the procedure had a significant association with AF recurrence at one year. Probably, early intervention of AF in HF patients will improve SR rate during follow-up.
Our study also analyzed the population with preserved LVEF. The recurrence rate of AF at one year of follow-up was higher than in the general population, however, they also benefited clinically with catheter ablation.
The rate of complications was higher in our study due to HF worsening, a complication that was not included in publications evaluating the general population (9.1% vs. 4.6%; p = 0.03).  We did not register major events such as death or stroke. Also, no patient required inotropic agents, vasopressors or mechanical ventilation.
Pathophysiology and previous studies
Atrial fibrillation and HF are two conditions that impair quality of life and reduce longevity. The prevalence of AF in patients with HF enrolled in clinical trials ranges between 15 and 45%.[15-19] Atrial fibrillation increases the risk of embolic stroke and tachycardiomyopathy, and is associated with reduced survival. The association between HF and AF worsens the prognosis, with a survival rate between 25 and 40% at 5 years according to the previous NYHA. Each condition increases the severity and worsens the outcome of the other.
There are several pathophysiological mechanisms that perpetuate both pathologies. Heart failure produces diastolic insufficiency, electromechanical remodeling of the left atrium, increased sympathetic tone and hydrosaline retention. This increases the rate of episodes of AF. Atrial fibrillation begins as an isolated ectopic activity mainly from the pulmonary veins. Subsequently, with the chronicity of both pathologies, the electrical and mechanical remodeling of the left atrium worsens, causing the perpetuity of the arrhythmia from multiple wave fronts. The electrical and anatomical changes associated with AF worsen heart failure, a situation that also worsens the evolution of atrial fibrillation, generating a vicious loop.
Several studies have compared the efficacy of rate control versus rhythm control in HF patients, but did not show better outcomes with one strategy over the other. However, these studies only used medical treatment for rhythm control with suboptimal efficacy to maintain patients in SR. In addition, 21% of the patients in the rhythm control group crossed over to the rate control group due to impossibility to maintain SR, and 10% of those in the rate control group crossed over to the rhythm control group, mostly due to HF worsening. The adverse events of the medications and the presence of contraindications in patients with structural heart disease were other factors that failed to maintain SR.
The superiority of CA over antiarrhythmic treatment in patients with symptomatic AF has been already demonstrated.[22-25] several studies analyzed the role of CA in HF patient using functional endpoints with different results.
The study by McDonald et al., included patients with persistent AF and advanced HF and failed to demonstrate significant improvement in LVEF and in other secondary endpoints as six-minute walk distance, quality of life and NTproBNP, compared with a rate control strategy. After 14 months, only 50% of the patients in the CA group remained in SR The inclusion of patients with persistent AF and advanced HF could explain the high rate of recurrence without achieving the final endpoints.
In patients with AF refractory to antiarrhythmic treatment, left ventricular dysfunction and HF in NYHA class II-III, pulmonary veins isolation showed significantly better quality of life, longer six-minute walk distance and higher LVEF compared with ablation of the AV node and biventricular pacing after 6 months.
The CAMTAF trial analyzed CA in patients with persistent AF, HF and LVEF < 50% and showed significant improvement of LVEF, oxygen consumption and quality of life at 6 months compared with rate control. Freedom from AF was achieved in 81% of patients at 6 months of follow-up without antiarrhythmic drugs. Despite the short follow-up period, the high rate of freedom from AF is associated with clinical improvement.
More recently, a study compared CA versus rate control in patients with persistent AF, HF and LVEF < 35%.The primary endpoint -improvement in oxygen consumption at 12 months- was significantly higher in patients undergoing CA. The Minnesota score and BNP also showed significant improvement. None of the studies mentioned above analyzed rehospitalization due to HF, a significant prognostic indicator.
Finally, the CASTLE-AF study, a randomized trial recently presented in the 2017 ESC congress, enrolled 363 patients with symptomatic paroxysmal or persistent AF, intolerance to take at least one antiarrhythmic drug, LVEF less than 35% and NYHA FC ≥2 with implantable cardioverter-defibrillator or cardiac resynchronization therapy-defibrillator with home monitoring capabilities. This study showed that catheter ablation was superior at preventing death or heart failure admissions (28.5% vs. 44.6%; p = 0.007). However, unlike our work, HF patients with preserved LVEF were not included. It is known that atrial fibrillation is a frequent cause of diastolic failure and that diastolic failure predisposes to AF recurrence after medical treatment or radiofrequency ablation. [28,29] Therefore, HFpEF patients would also benefit from catheter ablation.
The clinical impact found in our work is due to keeping patients with HF in SR. The success achieved with catheter ablation improves the functional class and reduces re-admissions for heart failure in HF patients with reduced or preserved LVEF.
This is achieved without increasing the rate of complications, as has occurred in pharmacological treatment trials to maintain SR. As we have previously seen, most of the studies evaluating CA in HF patients showed benefits in terms of quality of life, six-minute walk distance and LVEF. Our initial experience shows that the success rate at one year in patients with HF and AF treated with CA was acceptable, and that the patients who remained in SR had better NYHA functional class and fewer re-hospitalizations. Symptoms relief and reduction of hospitalizations are endpoints with a positive impact on the evolution of the disease and on the healthcare system. Likewise, patients with preserved LVEF, a poorly studied population, benefited as much as those with reduced ejection fraction.