Maximum diameter of LAA orifice and PDL
Imprecise assessment of LAA orifice, for example the selection of too
small LAAC device size based on TEE measurement, at preoperative phase
is one reason for the occurrence of PDL after the procedure. Other
factors linked to PDL are also suggested[14]. LAA
used to be considered to possess enough compliance to accommodate a
larger size LAAC device. However, the remodeling of LA and LAA in AF
patients may result in reduced compliance of LA and LAA, particularly in
response to a compressible LAAC device that is deployed at relatively
low radial force. Histological studies showed that the LAA specimens of
AF patients existed obvious dilatation, stretching and reduction of
pectinate muscle volume[15]. In addition, most
patients with chronic AF will exhibit significant thickening of
endocardium and deranged thickening elastic fibers extending to the
epicardium[16]. All these changes will reduce the
elasticity and compliance of LAA orifice, which increases the risk of
postoperative PDL due to mismatch of LAAC device and LAA orifice.
The maximum diameter of LAA orifice and LAA volume are indirect
evaluation indexes of LA remodeling. In this study, there were
significant differences in the maximum diameter of LAA orifice (P =
0.009) and LAA volume (P = 0.006) between PDL group and no PDL group,
suggesting that the remodeling and reduced compliance of LAA were
related to the presence of PDL. Further, in the multivariate logistic
regression analysis, the maximum diameter of LAA orifice served as the
only significant indicator, which independently predicted the risk of
PDL after LAAC procedure (OR, 1.31; 95% CI, 1.11-1.55; P = 0.002). The
probability of postoperative PDL is 1.31 times higher with an increase
of the maximum diameter of LAA orifice by 1 mm.
For those patients with larger size of LAA orifice and higher risk of
PDL, the application of Watchman device may be suboptimal and relate to
incomplete LAAC, since the available maximum diameter of the Watchman
LAAC device is 33 mm now. Larger Watchman LAAC device is therefore
warranted in the future to cover the need of these patients.