FIGURE 4.

Perinexal width correlates with pre-existing atrial fibrillation. (A) Representative TEM image from the Right (RAA, n = 8) and Left (LAA, n = 4) atrial appendages from the same patient (top). Wp is wider in LAA relative to RAA independent of observer (bottom). (B) Representative TEM images from the RAA of a patient with a history of AF (MAZE procedure, n = 10) and without a history of AF (n = 29) (top). Both blinded observers found in 39 patients that mean Wp between 30 and 105 nm is significantly larger in patients with pre-existing AF relative to those without (^∗p < 0.05, bottom).