Left Atrial Appendage Electrical Isolation (LAAEI)
The LAA is derived from the primordial LA mainly by the adsorption of
the primordial PVs and their branches, explaining its role as a
potential site of AF triggers. In a non-randomized population of 987
patients undergoing redo AF ablation, 27 % of patients were noted to
have triggers arising from the LAA. Moreover, in 8.7 % of the cases,
this was the only source of atrial arrhythmia with no PVs or extra-PV
reconnection (95).
The RCT BELIEF (Left Atrial Appendage Isolation in Patients with
Longstanding Persistent AF Undergoing Catheter Ablation) (96), showed
promising results with empiric LAAEI after both index and redo
procedures. Among patients who had recurrences and underwent redo
ablations, LAAEI was performed in all cases and re-isolated in cases of
reconnections. Late LAA reconnections were observed in 37 % of the redo
cases. RF and fluoroscopic times were comparable, with no increase in
complications. The incremental benefit of LAAEI in addition to PVI was
also demonstrated in two meta-analyses including approximately 2000
patients with non-PAF (97,98). This benefit persisted during a 5-year
follow-up of 1092 individuals in a propensity score-matched multicenter
cohort study. No differences in acute complications or thromboembolic
events were evidenced in patients on continued oral anticoagulation
(OAC) treatment (99). (Figure 11)
In a propensity score-matched study by Yorgun et al. (100),
cryoballoon-based isolation of the PVs and LAA delivered promising
results without a significant increase in complications. However, 4 %
of the study population had left circumflex artery vasospasm, which
resolved with intracoronary nitrate, and 1 % had left phrenic nerve
(LPN) injury. It is crucial to prevent mapping and ablation deep into
the LAA, as it is a thin structure, and ablation within the lumen is
associated with a higher risk of perforation and LPN injury. Imaging
integration with cardiac computed tomography and electroanatomic mapping
prior to ablation, can help mitigate the potential risk of coronary
injury (101). Periprocedural imaging and paced mapping can also
delineate the anatomical relationship of the LPN with the LAA, and in
case of close proximity a segmental isolation approach should be
considered (102).
The thromboembolic risks associated with LAAEI have been a major concern
and have shown mixed results. Rillig et al. (103) showed that at a
median follow-up of 6 months after LAAEI, 6 % of patients developed
stroke or transient ischemic attack, and 21 % were found to have LAA
thrombus on transesophageal echocardiogram (TEE). However, all 3
patients had AF recurrence at the time of stroke, and one was off OAC at
the time of event. In contrast, no significantly increased risk for
thromboembolic events was reported in the LAAEI groups from two
meta-analyses, even after a mean follow-up of 40.5 months (97,98). In a
large observational study of 1854 consecutive patients with AF receiving
LAAEI along with PVI, thromboembolic events were mainly seen in those
who had abnormal LAA function. Moreover, patients who were off OAC,
receiving subtherapeutic doses, or were non-compliant had thromboembolic
complications at higher rates (104). Interestingly, in patients who had
normal LAA function on TEE at 6 months, OAC was discontinued
irrespective of the CHA2DS2-VASc score,
and no thromboembolic events were seen during 2.3 years of follow-up.
For patients in whom long-term OAC is not suitable after LAAEI, LAA
occlusion could be considered (105). Another alternative for electrical
and mechanical isolation of the LAA is the ligation of the appendage
with Lariat, a suture delivery device (SentreHEART, Redwood, CA, USA).
This approach has been under investigation, and initially, concerns
regarding procedural complications, such as pericardial effusion and the
need for urgent cardiac surgery, were reported (106,107). Lakireddy et
al. demonstrated improvement in procedural success rate and mortality,
while also showing greater freedom from AF recurrence at 1 year
follow-up (108). In contrast, the aMAZE (LAA Ligation Adjunctive to PVI
for Persistent or Long-standing Persistent Atrial Fibrillation, NCT )
trial failed to demonstrate significant differences in arrhythmia
recurrence in patients undergoing left atrial ligation + PVI vs. PVI
alone (109).