Discussion
To the best of our knowledge, this is the largest study of LAAC using
the LAmbre device. We found a relatively high incidence of delayed PE/PT
after LAAC with the LAmbre device using a conventional implantation
method, mainly in patients with combined treatment. The MM for
implantation of the LAmbre device significantly facilitated full opening
of the umbrella, reduced the requirement of the recapture manoeuver, and
decreased the incidence of PE/PT. In multivariate Cox regression
analysis, an umbrella that was not fully open was the only factor
independently associated with delayed PE/PT events.
PE/PT is a serious complication, which mostly occurs during LAAC, but
rarely occurs after this procedure17. Schmidt et
al18 found that the PE/PT rate was significantly
higher in patients who were implanted with the Watchman device in the
EWOLUTION study during sinus rhythm than in AF rhythm (0.2% vs 1.5%;
P=0.02) at day 30 post-implantation. Delayed PT events that required
intervention only occurred in LAAC during sinus rhythm. The
investigators speculated that the main mechanism for their finding was
LAA contraction during sinus rhythm exerting mechanical force on the
device, which eventually led to PE/PT. Wolfrum et al19compared the efficacy and safety of LAAC with the Amplatzer Cardiac Plug
according to the different position of the device disc. No evidence for
a difference in the occurrence PE/PT was found between patients with
complete versus incomplete Amplatzer Cardiac Plug disc coverage of the
LAA ostium. In contrast, a recent study16 on the
Amulet device reported a tendency toward more PE/PT events after LAAC
with incomplete coverage of the LAA ostium by the proximal Amulet disc
(P=0.07). This previous study suggested that suboptimal positioning of
the device might be associated with worse periprocedural outcomes
independent of repositioning or exchange of the device during the
procedure. In our study, delayed PE/PT events were neither associated
with the coverage position nor recapture operation as analysed by
univariate and subsequent multivariate Cox regression
analyses.
Huang et al10 reported encouraging clinical outcomes
in patients with NVAF who had implantation of the LAmbre LAA occluder.
Three PT events (timing of the events was not specified) were documented
in their study. Park et al11 reported 2/60 (3.3%)
patients who underwent LAAC with the LAmbre device and suffered from PT
at days 8 and 33 after the procedure. Pericardiocentesis was required
for these two patients. A recent study with a small sample
size13 showed that 5 (29.4%) delayed PE events
occurred in 17 patients who underwent LAAC with the LAmbre device during
3 months of follow-up. Data from LAAC with the LAmbre device are
relatively inadequate and the safety of combining LAAC with the LAmbre
device and catheter ablation is unknown. In the present study, five of
six patients with delayed PE/PT required intervention in those with the
combined procedure. Only one PE event occurred among patients with
non-PAF who underwent isolated LAAC.
The umbrella of the LAmbre device has double hooks (eight small distal
hooks engaging into the LAA wall and eight U-shaped large hooks trapping
in LAA trabeculations) with the purpose of decreasing the risk of device
embolization. However, these eight U-shaped large hooks are bare and
slender. A narrow space with widespread trabeculations in the LAA
frequently interferes with opening of the umbrella. A stronger
mechanical force against the LAA wall might develop when any of these
hooks are not fully opened. Therefore, full opening of the umbrella is
important and is considered as one of the COST criteria (including
umbrella deployed beyond the Circumflex artery; umbrella fully Open;
peri-device with optimal Sealing (leakage ≤3 mm) for release of the
LAmbre device; and device stability confirmed by the Tug test) for
release of the LAmbre device. The modified implantation method in which
the umbrella is initially deployed half open outside of the LAA and
complete deployment into the landing zone facilitates full opening of
the umbrella. In our study, all of the patients with delayed PE/PT
showed incomplete opening of the umbrella in fluoroscopic imaging in the
CM group. Additionally, incomplete opening of the umbrella was
significantly associated with occurrence of delayed PE/PT events as
shown in the univariate model and multivariate Cox regression analysis.
The nadir of the U-shaped hooks at the same level as the radio-opaque
marker connecting the umbrella and the cover as shown in fluoroscopic
imaging is an important sign of full opening of the umbrella. However,
this is still insufficient to guarantee an appropriate mechanical force
from the double hooks against the LAA wall because full opening of the
umbrella was found in another two patients with delayed PT in the MM
group. One of these patients required surgical management because a
small branch of the left circumflex artery was likely injured by the
small hooks. This case was considered as an exception. In patients with
the combined procedure, contractile function of the LAA was gradually
restored when sinus rhythm was maintained after the procedure. We
speculate that relative movement between the bare large hooks and the
LAA wall causing friction during sinus rhythm was the leading cause of
perforation. Therefore, we strongly recommend using this MM for patients
with the combined procedure or isolated LAAC in those with PAF.
Performance of routine echocardiographic follow-up in this patient
population may be necessary. The manufacturer of the LAmbre device might
manage with the eight U-shaped big hooks in the next-generation product
design.