In Reply Drs Xia and Su raise several queries about our study, the aMAZE trial. First, they state, “The study did not assess left atrial appendage electrical isolation, which is important considering the mechanism of action of the intervention,” implying this affected outcomes. The proposed mechanism of action of LAA ligation as adjunctive therapy to PVI was 2-fold: LAA electrical isolation and left atrial volume (LAV) reduction. LAA ligation results in LAA ischemic necrosis, atrophy, and resorption, analogous to amputation. Prior studies indicate that LAA ligation leads to LAA electrical isolation. Verification of LAA isolation in our study would have required epicardial LAA sensing and capture, which was not feasible. The 1-year closure rate after LAA ligation in our study was 84%; thus, electrical activity would have been absent. The presence of LAA residual leaks, defined as residual communication between the left atrium and the LAA as determined on transesophageal echocardiogram or cardiac computed tomography, did not correlate with arrhythmia recurrence. From prior data, even with small leaks, the LAA body is electrically inert due to ischemic changes and often undergoes substantial atrophy.
