Comparison of Two Radiofrequency Ablation Devices for Atrial Fibrillation Concomitant with a Rheumatic Valve Procedure

Atrial fibrillation (AF) is a common cardiac arrhythmia characterized by irregular and rapid electrical activation of the atria, leading to unsynchronized atrial contraction and an increased risk of thromboembolism. In patients with rheumatic valve disease, AF is particularly prevalent and can significantly impact surgical outcomes if not addressed during valve procedures. The Cox maze procedure, particularly its modified versions using radiofrequency (RF) ablation, has become a standard surgical treatment for AF. This study compares the efficacy of two types of RF ablation devices—non-irrigation ablation forceps (AtriCure) and irrigation ablation devices (Medtronic)—in patients with rheumatic valve disease undergoing concomitant valve surgery.

The study retrospectively analyzed data from 278 patients who underwent the modified Cox maze RF ablation procedure at the Sichuan Provincial People’s Hospital between May 2013 and May 2017. Patients were divided into two groups: Group A (149 patients) received non-irrigation ablation forceps (AtriCure), and Group M (129 patients) received irrigation ablation devices (Medtronic). The primary objective was to compare the sinus rhythm (SR) restoration rates and procedural outcomes between the two groups.

Patient Demographics and Baseline Characteristics

The baseline characteristics of the patients in both groups were comparable. The average age of the patients was approximately 53 years, with a slight female predominance. The majority of patients had a long-standing history of AF, with an average duration of 26.3 months in Group A and 27.4 months in Group M. The left atrium (LA) diameter was slightly larger in Group M (58.1 mm) compared to Group A (57.4 mm), but this difference was not statistically significant. Other parameters, such as body mass index, cardiothoracic ratio, and left ventricular ejection fraction, were similar between the two groups.

Operative Approach

All procedures were performed via median sternotomy under cardiopulmonary bypass (CPB) with moderate hypothermia. The modified Cox maze procedure was performed with the aim of mimicking the incisions and sutures of the classical Cox maze procedure. In Group A, the AtriCure bipolar RF ablation device was used, while in Group M, the Medtronic irrigated RF ablation device was employed. The power generator for the Medtronic device was set at 25 W, with a saline irrigation flow rate of 4 to 6 mL/min. The ablation time was calculated from the start to the end of the procedure, and both devices were used to complete the entire ablation line.

The ablation protocol included right-sided procedures performed on the beating heart before aortic cross-clamping. Ablation lines were created between the superior and inferior caval cannulation sites, with additional lines drawn from the base of the excised right atrial appendage to the tricuspid valve annulus. In the left atrium, the left atrial appendage was amputated and oversewn, with ablation lines encircling the left and right pulmonary veins. Additional lines were drawn from the ablation line isolating the left pulmonary veins to the base of the left atrial appendage and the posterior mitral valve annulus. The Marshall ligament was also ablated.

Procedural Outcomes

The procedural outcomes were similar between the two groups. The RF ablation time was 28.9 minutes in Group A and 29.5 minutes in Group M, with no significant difference. The aortic cross-clamp time and CPB time were also comparable between the groups. A linear relationship was observed between the LA diameter and the RF ablation time, with the predicted RF time to LA diameter being slightly higher in Group M.

Post-operative outcomes, including the neutrophil-lymphocyte ratio (NLR) and troponin I (TnI) levels at 12 hours post-operatively, were similar between the groups. Seven patients in Group A and five in Group M experienced transient severe atrioventricular block, which was managed with temporary pacemaker support. Two patients in each group required permanent pacemaker implantation.

Sinus Rhythm Restoration

The SR restoration rates were similar between the two groups. At discharge, 75.2% of patients in Group A and 73.6% in Group M were in SR without the use of anti-arrhythmic drugs. At 6 months, the SR rates were 72.5% in Group A and 71.3% in Group M, and at 12 months, the rates were 70.5% and 69.8%, respectively. These differences were not statistically significant.

Discussion

The study demonstrated that both non-irrigation and irrigation RF ablation devices were equally effective in restoring SR in patients with rheumatic valve disease undergoing concomitant valve surgery. The procedural outcomes, including ablation time, CPB time, and post-operative complications, were comparable between the two groups. The SR restoration rates at discharge, 6 months, and 12 months were similarly high, indicating that both devices are effective in achieving long-term rhythm control.

The rationale for restoring SR during valve surgery includes improved survival, reduced thromboembolism risk, elimination of the need for long-term anticoagulation, and improved cardiac output. The modified Cox maze procedure has been shown to be safe and effective in a broad range of patients, including those with high surgical risk. Bipolar RF ablation has become the preferred method due to its shorter procedure time and greater guarantee of transmural lesion formation.

The study also highlighted the importance of LA size in determining the success of RF ablation. A larger LA diameter was associated with longer ablation times, but the SR restoration rates were not significantly different between the groups. This suggests that both devices are capable of achieving transmural lesions even in patients with enlarged atria.

Limitations

The study was a single-center, retrospective analysis, which introduces inherent selection biases. The findings should be validated in prospective, randomized trials to standardize the procedures and enable more robust comparisons. Additionally, the follow-up period was limited to 12 months, and longer-term outcomes were not assessed. The use of 24-hour Holter monitoring may have underestimated the incidence of AF recurrence, and longer monitoring periods may be needed in future studies.

Conclusion

In conclusion, both non-irrigation and irrigation RF ablation devices are equally effective in restoring SR in patients with rheumatic valve disease undergoing concomitant valve surgery. The procedural outcomes and SR restoration rates were similar between the two groups, indicating that both devices are viable options for surgical AF ablation. The choice of device may depend on surgeon preference and institutional availability, as both have demonstrated comparable efficacy and safety.

doi.org/10.1097/CM9.0000000000000276

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