Can we predict the risk for atrial fibrillation recurrence after concomitant surgical atrial fibrillation ablation and should this influence our treatment strategy?

Concomitant surgical atrial fibrillation (AF) ablation is an established therapy in AF patients undergoing cardiac surgery, recommended in guidelines [1, 2]. Since the first application of the procedure by Cox [3] in 1987, the technique has been modified and the cut-and-sew principle was replaced by transmural atrial lesions, created by various thermal energy sources such as radiofrequency or cryotherapy. The simplification of the initial cut-and-sew principle led to a more widespread application of the procedure, which is today known as the Cox-maze IV procedure and is the gold standard for the surgical treatment of AF [4]. In their article, Kakuta et al. have reported the experience of concomitant surgical cryoablation in 450 patients with persistent AF that were treated between 2001 and 2019. The median follow-up duration was 5.2 years [5]. First, the authors have to be congratulated on their results of the study. A 1-year rate of freedom from AF of 91.4% in a population with persistent AF is an excellent result. Although there is a slight reduction in success rate in long-term follow-up, a freedom from AF rate of 76.2% at 10-year follow-up is still very good, and far beyond what every other interventional or hybrid therapy of AF can provide for patients with persistent AF. The authors have furthermore created and validated a risk score for the recurrence of AF in patients undergoing concomitant AF ablation. Using the 4 variables, F-wave voltage in V1 < 0.2 mV, preoperative AF duration >5 years, left atrial volume index >100 ml/m and age >70, a risk score model with a range up to 10 was introduced. Using their risk model, they have shown that in patients with for example a high-risk score of >7, there was a 50% probability for AF recurrence at latest follow-up. The validity of the model has been tested and its simplicity and accuracy makes it a useful tool to predict the probability of AF recurrence after concomitant surgical ablation. This helps the physician and the patient to get a closer idea of what to expect after a concomitant surgical AF ablation procedure. However, the authors conclude in their article that the use of Cryo-Maze therapy should be considered carefully in patients with a higher model score. I do not agree with this statement. A probability of sinus rhythm restoration of about 50% in a high AF recurrence risk group does not seem too bad for me. Why not giving those patients at least a 50% chance of sinus rhythm restoration? It has been shown that surgical AF ablation does not add mortality or morbidity to the procedure. Even in high-risk patients, it has been shown that the addition of surgical AF ablation is safe and effective [6–8]. So, the risk model gives us just a risk for ablation failure, we are not setting the patient at risk for harm. Therefore, in a concomitant AF ablation setting, we are operating on that patient anyways, why not performing an ablation and giving him the best chance of sinus rhythm restoration he will ever have? The risk model, however, can be useful when giving informed consent to the patient and explaining him its probability of ablation success. We of course should explain to a patient with a high-risk score that his chance of sinus rhythm restoration is probably not 80% or 90%, but that there is definitely a chance of sinus rhythm restoration, without adding additional risk. Given the several beneficial effects of concomitant surgical AF ablation, including reduction in stroke and mortality in the short- and long-term run, performing the procedure is definitely worth the effort, even in patients with a lower probability of success [4, 8]. In contrast, I think in those patients with a high AF recurrence risk, we should use our best skills and tools and do whatever has the highest probability for sinus rhythm restoration. This is performing a full concomitant Cox-maze VI lesion set [9]. Although not validated in patients with lone AF, such a risk score could be a valuable tool to identify the success probability in patients undergoing a stand-alone ablation. In those patients where an operation would only be performed for the treatment of AF, the risk score could help the physician and patient to guide the decision if an operation with a reasonable success probability can be achieved.