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Page 8 of 13 Maurina et al. Mini-invasive Surg 2021;5:53 https://dx.doi.org/10.20517/2574-1225.2021.88

[36]
[17]
protocol has been tested only for both the WATCHMAN™ and the Amulet devices, it is nowadays
applied for all LAAO devices. A shorter DAPT duration (1-3 months) followed by SAPT may be considered
in patients at high bleeding risk. In the case of prohibitive bleeding risk, shorter antithrombotic regimens, or
even no therapy at all, may be considered, after careful evaluation.

After the first period (3-6 months or lower) of DAPT, SAPT is the treatment of choice for patients
undergoing LAA percutaneous closure. There is no definite consensus whether SAPT should be carried on
indefinitely: however, in accordance with Glikson et al. , SAPT should be prescribed indefinitely or at least
[12]
for the first year after the procedure. Aspirin is generally the drug of choice for long-term treatment, unless
contraindicated.

Antithrombotic therapy suboptimal or complicated LAA closure
The most common complications after LAAO are device-related thrombosis (DRT) and incomplete
occlusions. TEE is the most accurate way to check for both complications; however, it is not systemically
performed after LAAO, especially when a good procedural result is obtained.

DRT has been a historically rare complication of percutaneous LAA closure, ranging from < 2% to 5% .
[37]
However, according to data published more recently, DRT prevalence may complicate up to 38% of LAAO
procedures . DRT exhibits an increased risk of all-cause mortality and stroke: these patients’
[38]
thromboembolic risk is estimated to be even higher than what would be expected by their baseline
CHA2DS2-VASC score [39,40] . DRT may appear even months after LAAO and no strong correlation with on-
going antithrombotic treatment has been found . Anticoagulation with subcutaneous heparin or OAC
[39]
until thrombus dissolution is the treatment of choice for DRT ; however, it poses a significant dilemma in
[12]
patients with an absolute contraindication to OAC. Sedaghat et al. recently demonstrated that DRT
[39]
resolution may be achieved even with other antithrombotic therapies, but no strong evidence exists.
Incomplete occlusion of the LAA may be procedure related or may be secondary to delayed or incomplete
endothelialization of the device. Despite being made of a deformable material such as nitinol, devices come
in a finite number of sizes and usually with a circular shape: therefore, they may not adapt correctly to each
LAA anatomy which typically exhibits an oval orifice. Small (< 5 mm at TEE evaluation), incomplete
occlusions of the LAA are generally clinically irrelevant and may resolve spontaneously over time; therefore,
[41]
OAC therapy would not be useful . Moreover, even in larger incomplete LAA occlusions, OAC does not
[41]
seem to be associated with stroke risk reduction .
Therefore, regardless of complete LAA exclusion, no strong recommendation about adjunctive OAC after
the procedure exists. However, four weeks of anticoagulation with low-molecular-weight heparin or VKA, if
tolerated by the patient, followed by trans-esophageal echocardiogram reevaluation, appears to be a
[42]
reasonable therapeutic approach in the case of incomplete LAA exclusion or thrombosis .

GAPS IN EVIDENCE AND FUTURE PERSPECTIVES
The first and main gap in evidence is that initial randomized controlled trials comparing LAAO and
anticoagulation showed good procedural results, and device performance emerged as non-inferior as
compared to standard medical therapy in the overall population [13,14] . However, percutaneous LAA occlusion
is still considered (in both guidelines and clinical practice) as an option for patients with absolute
contraindication to oral anticoagulant therapy or for those with prohibitive bleeding risk. A tendency
toward a more liberal use of the procedure was registered in real world practice, reinforcing doubts about
the non-receipt of evidence in the guidelines.