Modified Left Atrial Maze Procedure: Achieving a Balance Between Safety and Efficacy in Concomitant Atrial Fibrillation Ablation

This prospective observational registry was designed to evaluate the outcomes, safety profile, and predictive factors associated with a standardized modified left atrial Maze procedure performed concomitantly with cardiac surgery. The study focuses on the application of a reproducible lesion set, including a complete posterior left atrial "BOX" isolation and systematic left atrial appendage (LAA) closure, using bipolar radiofrequency, cryothermy, or a combination of both energy sources. The protocol reflects a structured institutional strategy developed at the University Hospital of Toulouse, allowing consistent perioperative management, uniform rhythm follow-up, and systematic quality-of-life assessment.

The modified left atrial Maze procedure aims to interrupt reentrant electrical circuits responsible for atrial fibrillation (AF) through the creation of continuous, transmural scar lines. In non-mitral procedures, the lesion set consists of pulmonary vein isolation and roof and floor lines creating a posterior "BOX." For mitral valve surgery, the standard lesion set is supplemented by a mitral isthmus line applied endocardially and epicardially to ensure transmurality. The LAA is excluded either through surgical excision with suture closure or via an external clip device. All lesion sets are performed concomitantly with the index cardiac procedure under cardiopulmonary bypass.

Postoperative management follows standardized institutional protocols including early beta-blockade, short-term amiodarone when indicated, rhythm monitoring, and systematic lifelong anticoagulation based on current guidelines. The structured follow-up schedule includes rhythm assessment by ECG, 24-hour Holter monitoring, or pacemaker interrogation at 3 and 12 months. Quality of life is assessed at baseline, 3 months, and 12 months using a simplified validated questionnaire derived from the SF-36 instrument.

Registry quality procedures include predefined data validation rules, routine checks for missing or inconsistent entries, and verification of collected data against source clinical records. All variables are defined within a standardized data dictionary specifying coding conventions, units, and clinically relevant thresholds. Data entry is performed by trained personnel within secured institutional electronic systems governed by the French MR-004 regulatory framework for clinical data handling. Periodic oversight is provided by the institutional data protection officer.

The sample size reflects the total number of eligible consecutive patients undergoing concomitant surgical AF ablation within the predefined inclusion period. Missing data are handled using a complete-case approach when the proportion of missing values remains below 5%, consistent with the predefined statistical plan. No imputation is performed when missingness is low and not expected to influence outcome distribution.