BACKGROUND: A newly designed ablation clamp was used with cryoablation via left atrial appendage (LAA) entry & exclusion to create a first in human left-sided Maze. Endocardial ultrasensitive mapping (EUM) was used to validate endpoints similar to traditional Cox-Maze IV, but using an efficient approach to improve adoption.
METHODS: In a retrospective study, patients presenting for open heart surgery with either valvular and/or coronary artery disease with known non-paroxysmal AF underwent concomitant AF ablation. A magnetized catheter was used to assist in placement of a bipolar RF clamp around pulmonary veins (PVs) & left atrial posterior wall (LAPW) to achieve en-bloc electrical isolation. A linear cryoprobe was then used to create endocardial connecting lesions from opened LAA back to en-bloc isolation and down to anterior mitral valve annulus. The ligament of Marshall (LOM) was interrupted, and LAA was ligated using a clip (Figure 1). Following ablation, EUM was performed to ensure transmural electrical isolation (Figure 1 inset).
RESULTS: A series of 12 patients had the novel left-sided Maze with endocardial mapping. The cohort included 58.3% male patients (mean 68.3 years), left atrial mean diameter 4.4 cm. 33% of patients had CABG, 41.7% had mitral valve repair/replacement, & 16.6% had AVR. Average CHA2DS2-VASc was 3.6. Mean ablation time was 15 minutes. Transmurality & electrical isolation were documented of LAPW & PVs using the lowest detectable EUM voltage sensitivity (0.01mV) in 100% of patients (Figure 1 inset). Integrity of the anterior peri-mitral cryoprobe line was assessed using high-density electroanatomic wavefront mapping showing bidirectional block of the annulus. Standard epicardial/endocardial posterior mitral isthmus ablation was not required to achieve isolation. The final lesion set consisted of electrical isolation of PVs, LAPW, LAA, LOM, left superior PV to LAA and LAA to mitral annulus. No complications were observed.
CONCLUSIONS:This novel left-sided Maze lesion set represents several multidisciplinary achievements including application of a new RF ablation clamp & implementation of iterative lesion design using EUM to not only improve efficacy but also to create a comparable lesion set lowering the steep learning curve needed to effectively perform Cox-Maze IV ablation; the latter explaining poor procedural adoption.