Transmural Atrial Fibrosis after Epicardial and Endocardial Argon-Powered CryoMaze Ablation

Which Method to Use for Surgical Ablation of Atrial Fibrillation Performed Concomitantly with Mitral Valve Surgery: Radiofrequency Ablation versus Cryoablation

Objective

The effects of energy source on the maintenance of sinus rhythm and the contribution of demographic characteristics to the case selection in patients submitted to ablation performed concurrently with mitral valve surgery were analyzed.

Methods

Cryothermal (n=42; 43.8%) and radiofrequency (n=54; 56.3%) energy were employed in 96 patients submitted to mitral valve replacement and Cox maze IV procedure. Patients were called for control visits between 15 days and 12 months after discharge. The causal relationship between recurrence of atrial fibrillation and factors such as left atrial diameter, C-reactive protein, hypertension, left ventricular ejection fraction, chronic obstructive pulmonary disease, and body mass index was determined.

Results

Maintenance rates of the sinus rhythm with radiofrequency and cryoablation were 97.6% and 96.3%, respectively, in the first postoperative month, whereas at the 12^th postoperative month were 88.1% and 83.3%. No significant difference was found between groups in relation to the energy source. Sensitivity and specificity for left atrial diameter with a cut-off value of 50.5 mm were 85.7% and 70.7%, respectively. Sensitivity and specificity for C-reactive protein with a cut-off value of 12 mg/dL on the 15^th postoperative day were 83.3% and 88.9%, respectively. The effect of body mass index on atrial fibrillation recurrence was 3.2 times. Sensitivity and specificity for left ventricular ejection fraction 37% cut-off value were 96.3% and 11.4%, respectively. Atrial fibrillation in hypertensive cases was 5.3 times more. In patients with chronic obstructive pulmonary disease, recurrence of atrial fibrillation was 40%. The causal relation between recurrence of atrial fibrillation and the studied factors was established.

Conclusion

Demographic characteristics have a significant impact on ablation efficiency, while the type of energy source does not.

The surgical treatment for atrial fibrillation: ablation technology and surgical approaches

The Cox maze procedure developed originally in 1987 by Dr James Cox has evolved from a "cut and sew" surgical procedure, where the maze was applied using multiple surgical cuts, to an extensive use of surgical ablation technology where ablation lesions are placed with alternative energy sources (radiofrequency, cryothermy, microwave, and high-frequency ultrasound). Furthermore, the procedure has changed from a median sternotomy approach only to one that can be performed minimally invasively and robotically. The purpose of this paper is to review the current available technology for the ablation of atrial fibrillation as well as the different procedural approaches for the surgical ablation of atrial fibrillation.

Outcome of concomitantCox-maze III procedure using an argon-based cryosurgical system: a single-center experience with 250 patients

BACKGROUND

The Cox-Maze procedure (CM) for atrial fibrillation (AF) is associated with a high rate of sinus restoration. This study assessed the safety and efficacy of concomitant CM using an argon-based cryosurgical platform only.

METHODS

Data were collected prospectively for 250 consecutive patients undergoing concomitant cryosurgical CM. We examined baseline characteristics, perioperative and postoperative outcomes, health-related quality of life (Medical Outcomes Trust SF-12 Health Survey and AF Symptom Checklist) and Kaplan-Meier survival analysis.

RESULTS

Mean age was 64.3 ± 12.1 years, AF duration was 35.7 ± 54.2 months, left atrial size was 5.2 cm (range, 3.1 to 11.0 cm; 16.8% > 6 cm), 86% had nonparoxysmal AF, with history of cardioversion in 32% and catheter ablation in 8%. Concomitant procedures were mitral valve operation in 69.6%, coronary artery bypass graft in 29.2%, aortic valve replacement in 22.0%, with 46% multiple concomitant procedures and 16% with a previous cardiac operation. Perioperative outcomes were 5 deaths (2%), 3 strokes (1%), 1 transient ischemic attack (<1%), and 4 pacemakers for sinus node dysfunction (2%). There were no late thromboembolic events (mean follow-up, 28.2 ± 23.7 months), and 11% were taking warfarin for atrial arrhythmia at 1 year. Significant improvement in health-related quality of life (p < 0.001) was noted. At 24 months, 92.4% of patients were in sinus rhythm; with 82.8% in sinus rhythm off antiarrhythmic drugs. Two-year cumulative survival was 91%.

CONCLUSIONS

The cryosurgical CM procedure can be performed safely and effectively as defined by the low number of postoperative morbidities, high return to sinus rhythm off antiarrhythmic drugs, and low rate of thromboembolic events, with most patients off anticoagulation by 2 years.