The role of surgical ablation for atrial fibrillation (AF) has experienced a re-evaluation, similar to other procedures in recent years, due to a shift in focus on how certain heart conditions are perceived. Tricuspid regurgitation and left atrial appendage closure, also associated with AF, have followed a similar trajectory, leading to an overestimation of potential treatment candidates and blurring the lines between clinical utility and futility—all in the interest of generating case series. While ablation was never entirely abandoned, it thrived more decades ago, later facing a phase of disenchantment where recurrent arrhythmia cast it “more as a means to understand AF than as a true cure.”

Earlier periods allowed the development of concomitant AF ablation, including the description of cut-and-sew lesion patterns, the emergence, refinement, and selection of energy-based devices, surgical team training, and eventually integration into minimally invasive approaches, extending its application to isolated AF ablation. This growing case volume improved identification of candidates with lower recurrence rates (non-rheumatic valve disease, left atrial diameter <50 mm, non-permanent AF, and other markers of lesser atrial remodeling), avoidance of mistakes such as discontinuing oral anticoagulation (even when left atrial appendage was closed, and sinus rhythm remained stable), or limiting the excessive prolongation of extracorporeal circulation times and associated morbidity. European guidelines thus provided class IIa indications for symptomatic AF and IIb for asymptomatic cases considering concomitant ablation with other cardiac surgery. In American guidelines, concomitant ablation is class IA for mitral valve surgery and IB for aortic valve and/or coronary procedures. Despite high recurrence rates, the largest meta-analysis by McClure et al., including 23 clinical trials, revealed that concomitant ablation offers benefits in maintaining sinus rhythm, though it lacks survival impact.

Cheng et al. conducted an analysis of Taiwan’s national health database from 2001 to 2016. They included 11,495 patients with preoperative AF undergoing diverse cardiac surgeries, of whom 3,255 had concomitant ablation, while 8,204 did not. After propensity score matching in a 2:1 ratio, comparisons were made between 2,828 patients with concomitant ablation and 4,106 without ablation. Radiofrequency was used in 71.2% of cases, and cryoablation in 28.8%. No differences were observed in hospital mortality (ablation 5.4% vs. 6.7%) or pacemaker implantation need (4.3% vs. 4.2%) among other analyzed perioperative complications. Likely related to prolonged surgical times and increased technical complexity, the ablation group showed higher rates of re-exploration due to bleeding (2.9% vs. 2.6%; p = .0029). With a mean follow-up over five years, mortality was significantly lower in the ablation group (5.7% vs. 7.7%, p < .0001), as were ischemic stroke (1.8% vs. 2.5%, p = .0013) and readmission rates (25.2% vs. 27.9%, p = .0095). There were no differences in pacemaker implantation need during follow-up (approximately 1.4%) or gastrointestinal bleeding (around 1.6%).

The authors conclude that concomitant AF ablation is safe and does not significantly increase perioperative complication rates, providing greater long-term benefits compared to isolated cardiac surgery without concomitant AF ablation, particularly in terms of improved patient survival.

COMMENTARY:

The study by Cheng et al. is one of the few in which concomitant AF ablation demonstrates a survival benefit. This work boasts strong statistical power, a major limiting factor in previous studies, though the aggregated evidence in McClure et al.’s meta-analysis similarly could not establish such an effect.

Given these results, one question arises: How is this outcome possible? Various explanations could account for this finding, though the retrospective design introduces limitations and potential biases. First, the authors do not precisely describe preoperative AF characteristics, lesion patterns applied, or success rate in restoring sinus rhythm with/without antiarrhythmic support and effective atrial transport function (a-wave >0.3 m/s). This might have resulted in abnormally favorable outcomes, stemming from a sample with a high representation of paroxysmal AF and/or lower degrees of remodeling, essentially a selected population. In fact, alongside unequal follow-up and methods used (from spot ECG to implantable Holter), these factors account for the vast differences in rhythm restoration rates across studies (<40% to >80%). Second, left atrial appendage closure invariably contributes to clinical benefits. Its closure rates surpass those in patients not undergoing ablation. Although this procedure is inherent to ablation, it is a classic confounding factor, particularly now recognized as an independent protector against stroke and other major cardiovascular events. Finally, lack of randomization allows for preprocedural candidate selection bias, which may have included patients in poorer health, more advanced cardiac disease, or morbidities not accounted for in the propensity analysis, ultimately impacting survival outcomes. Neither antiarrhythmic nor anticoagulant protocols (including the adoption of direct-acting anticoagulants within the study period) are analyzed, both pivotal in influencing morbidity and mortality in AF patients.

Regardless, surgical AF ablation is experiencing a renaissance, particularly in the field of isolated ablation but also in concomitant procedures. For the latter, lessons learned may lead us to consider candidate selection as crucial, particularly for cases with difficult rate control, typically symptomatic and paroxysmal in nature. For many such patients, if not a cure, at least AF burden reduction (time in AF during the day) likely contributes to symptom relief and the prevention of future complications with prognostic impact, such as stroke, functional valve regurgitation (mitral and tricuspid insufficiency), or tachycardiomyopathy. For cases with low success probability, technical complexity, and/or high surgical risk, adequate exclusion of the left atrial appendage remains an alternative to reduce stroke risk. Years ago, we perhaps over-abated or ablated poorly, and recently, we may have ablated too little. Concomitant surgical AF ablation is still seeking its role, its position, and its level of acceptable outcomes. It is clear that the time has not yet come to abandon it, but rather to improve candidate selection.

REFERENCE:

Cheng YT, Huang YT, Tu HT, Chan YH, Chien-Chia Wu V, Hung KC, Chu PH, Chou AH, Chang SH, Chen SW. Long-term Outcomes of Concomitant Surgical Ablation for Atrial Fibrillation. Ann Thorac Surg. 2023 Aug;116(2):297-305. doi: 10.1016/j.athoracsur.2022.09.036.