Early Results of the Modified Right Atrial Lesion Set for the Cox-CryoMaze Procedure

The standard right atrial lesion (RAL) set, as originally outlined in the Cox-Maze III procedure, can be technically challenging when using a cryoprobe to create the lesions. We report our initial experience with an alternative set of RALs for the surgical treatment of atrial fibrillation (AF).

Between September 2011 and January 2015, a total of 112 patients underwent a CryoMaze procedure with biatrial lesions using argon-based cryoablation (cryoprobe temperature, -160°C). Although the standard left atrial lesion set was used, the RAL pattern was modified in this cohort of patients. The intracaval superior vena cava-inferior vena cava lesion was performed as in the pattern described for the standard Cox-Maze III procedure. In addition, a horizontal atriotomy incision (the "T" lesion) in the mid free wall of the right atrium was based roughly in the midintercaval line and extended medially as a linear cryolesion to the lateral tricuspid annulus at the so-called 2-o'clock position as in the Cox-Maze III lesion pattern. Ordinarily, a linear cryolesion would be placed from the tip of the right atrial appendage (RAA) to the anterior tricuspid annulus at the so-called 10-o'clock position to prevent macro re-entry around the base of the RA appendage. Our modification consisted of, instead, a linear cryolesion directed perpendicularly from the mid portion of the atriotomy (T lesion) to the tip of the RA appendage, which simply interrupted RAA re-entry at another point.

The mean ± standard deviation age was 72.7 ± 10.6 years, 56.3% were males, and 63.1% had long-standing persistent AF. There were three operative deaths (2.6% with an observed over expected of 0.58), all in the concomitant procedures with associated cardiac disease. Overall follow-up was 91.3%. Freedom from AF at discharge, 1-, 3-, 6-, 12-, 24-month, and last follow-up [16.1 ± 11.3 months (range, 0.4-43 months)], was 100%, 76.3%, 84.2%, 98.3%, 89.5%, 89.2%, and 90.5%, respectively. Similarly, freedom from antiarrhythmic drugs was 74% and 81%, whereas freedom from anticoagulants was 72% and 78% at 12 and 24 months, respectively.

These results suggest the modified RAL set to be an effective alternative to the traditional RALs of Cox-Maze III. By substituting this lateral RAA lesion for the more technically difficult medial lesion, the procedure becomes easier to perform and favorably impacts operative time while achieving comparable results in reducing AF burden.