Rochus K. Voeller, Marci S. Bailey, Andreas Zierer, Shelly C. Lall, Shun-ichiro Sakamoto, Kristen A. Aubuchon, Marc R. Moon, Richard B. Schuessler, Ralph J. Damiano; Cardiothoracic Surgery, Washington University School of Medicine, Saint Louis, MO
Objective: The Cox-Maze (CM) procedure remains the gold standard for the surgical treatment of atrial fibrillation (AF). In the latest version, the CM IV, most of the incisions have been replaced with bipolar radiofrequency (RF) ablations. The importance of each ablation line remains unknown. The purpose of this study was to determine if there were differences in surgical outcomes in the CM IV performed either with a single connecting lesion between the right and left pulmonary vein (PV) isolations vs. two connecting lesions between the PVs. The latter, termed a box lesion, electrically isolates the entire posterior left atrium (LA).Methods: Data were collected prospectively on 137 patients who underwent the CM IV from April 2002-September 2006. Before May 2004, the PVs were connected with a single bipolar RF ablation lesion (n=56), while after this time a box lesion was routinely performed (n=81). No patient was lost to follow-up and the mean follow-up was 11.8±9.6 months. Patients had ECGs at 1, 3, 6, and 12 months and patients with symptoms and atrial tachyarrhythmias (ATA) had 24-hour holters.
Results: There were no statistically significant differences in age, gender, AF type, NYHA Class, LVEF, or LA diameter between groups. Also, there were no statistically significant differences in operative mortality, stroke, reoperation for bleeding, pacemaker placement, ICU and hospital stay. However, there were significantly higher early ATA in the single connecting lesion group compared to the box lesion group (40/56, 71.4% vs. 30/81, 37.0%, p<0.001). Freedom from AF recurrence was also significantly higher in the box lesion group at 1-month (65/75, 86.7% vs. 37/54, 68.5%, p=0.01) and at 3-month follow-up (64/66, 97.0% vs. 44/52, 84.6%, p=0.02). The use of antiarrhythmic drugs was significantly lower in the box lesion group at 6-month follow-up (7/46, 15.2% vs. 23/49, 46.9%, p=0.001). There was a trend toward higher freedom from recurrent AF at late follow-up in the box lesion group (73/75, 97.3% vs. 47/53, 88.7%, p=0.06).
Conclusion: A box lesion instead of a single connecting lesion between the PVs showed a significantly lower incidence of ATA, higher freedom from AF recurrence at 1 and 3 months, and a lower use of antiarrhythmic drugs at 6 months. This likely is the result of box lesion isolating the entire posterior LA, which is an important source of triggers for the initiation and substrates for the maintenance of AF. A box lesion should be performed in all patients undergoing the CM procedure.
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