Discussion
Acute pericardial effusion and tamponade during deployment is a
recognized though uncommon complication of LAAC. The incidence of
pericardial effusion in both the EWOLUTION registry and the Boston
Scientific manufacturer-compiled registry is less than 1%,
significantly lower than reported in the original trials (3,4). Delayed
pericardial effusion after LAAC is even less common (5). Regardless of
timing, such effusions can lead to cardiac tamponade and even death.
Avoidance and recognition of procedurally-related pericardial effusion
are imperative to the LAAC operator.
As far as we know, this is the first case series to report delayed
pericardial effusion following LAAC with WATCHMAN FLX™. The mechanism in
both of these cases was likely microperforation during implantation. One
plausible explanation would be that the J-shaped fixation anchors of the
WATCHMAN FLX™ device caused appendage microperforations during the
procedure, an etiology that has been theorized in the PINNACLE FLX trial
(2). In both cases presented, the patient was in sinus rhythm at the
time of the procedure and noted to have a hyperdynamic left atrial
appendage on contrast injection. We hypothesize that this hyperdynamic
state may have caused increased anchor tissue engagement leading to
appendage microperforation.
The appearance of “auto-tug”—where the core wire moves automatically
back and forth within a loosened hemostatic valve—is not an uncommon
finding noted prior to WATCHMAN™ release. Tightening the hemostatic
valve on the core wire in this situation may put strain upon the
appendage, especially in the setting of a hypermobile or hyperdynamic
appendage, causing the anchors to repeatedly pull upon appendage tissue.
Therefore, we recommend loosening the hemostatic valve from the core
wire, allowing the core wire to move freely in these situations until
device release. When the “tug test” is performed, it should be
performed very gently. Though the exact mechanism of microperforation is
not well understood, attention to the interaction of the WATCHMAN™
device, delivery system, and the appendage may help to reduce the chance
of inadvertent appendage perforation.