The procedure is performed in a standard cardiac catheterization laboratory. An anesthesiologist, an imager, and the implanter are the main participants in the procedure. The patient is given general sedation to protect the airway during extended TEE imaging and to prevent potential sudden movements by the patient, which may cause cardiac perforation while manipulating LAA. The C-arm fluoroscopy is positioned just to the left of the operator, allowing more freedom of movement for the echocardiographer, who sits at the head of the table. Echocardiographers and anesthesiologists are provided with appropriate radiation shielding. The operator can see TEE images in real-time with the ultrasound machine slaved to the boom.[29][37]

Pre-procedural transesophageal echocardiogram (TEE) is used for evaluating suitable candidates and determining the LAA morphology and dimensions. Important elements to be determined are the shape and size of the ostium, the width of the landing zone, the LAA length, and the number, shape, and location of the lobes if possible.[38] The landing zone is defined as the area within the LAA where the device will be positioned. Additional pre-procedural imaging with computed tomography (CT) or magnetic resonance imaging (MRI) should be considered in the presence of large LAA neck width (greater than 26 mm) or a complicated LAA anatomy. Given size limitations associated with each device, good pre-procedural planning avoids unnecessary termination of the LAA closure procedure after the patient has undergone induction with general anesthesia.[39][37][40][41] In addition, the LAA size depends on LA pressure and the presence of sinus rhythm or AF. Hence, certain operators prefer measuring LAA dimensions during the procedure after saline infusion establishes an LA pressure of greater than 10 mm Hg. In order to rule out post-procedural pericardial effusion and device embolization, many institutions and centers perform a chest radiograph and a TTE. To verify the complete sealing of the LAA and the absence of a thrombus, a TEE is recommended after 45 days. Post LAA closure, various antithrombotic/anticoagulation regimens have been used, including warfarin, dual antiplatelet therapy (DAPT), direct oral anticoagulants (DOAC), aspirin monotherapy, and no therapy. Therapy with either DAPT or DOAC does not significantly increase the incidence of device thrombus, stroke, or bleeding compared with standard warfarin therapy.[42] 

Implantation of the device 

Percutaneous LAA closure is generally performed with general anesthesia guided by TEE and fluoroscopy. Prior to the procedure, antibiotic prophylaxis is usually given. Vascular access is achieved via a femoral vein, and transseptal puncture using a standard transseptal needle and sheath is done for the delivery system. The puncture site in the fossa is preferably inferior and posterior in order to have a good alignment with the LAA axis. Furthermore, there are different curves of sheaths available for accessing LAA. A bolus of unfractionated heparin should be provided after the puncture to obtain an activated clotting time (ACT) of more than 250 s. The size of the device is chosen based on LAA dimensions (ostium, neck width, depth) with the help of TEE and contrast angiography (right anterior oblique 30°/ cranial 30°). The desired implantation angulation of C-arm may vary greatly from patient to patient. TEE and fluoroscopy ensure the location of the device in the LAA. The sheath over the device reduces the risk of perforation, and the device is subsequently deployed. A ‘tug test’ is performed, once the device is in position to confirm device stability. Color Doppler imaging verifies complete sealing. The device is finally released from the delivery cable, and potential complications (e.g., pericardial effusion) are ruled out. The individual steps differ from one device to another and are described below.  

Watchman 

The device is selected by determining LAA size by the combination of TEE and fluoroscopic measurements. TEE excludes the presence of LAA thrombus prior to the procedure. However, cardiac CT can also be used for pre-procedural planning.[43] In the inferoposterior part of the interatrial septum, a 14-Fr double- or single- curved access sheath is inserted into the LA through a transseptal puncture. The 14-Fr sheath is placed deep inside the LAA and often telescoped over a diagnostic pigtail catheter in order to prevent laceration and perforation of LAA. The device is preloaded in a delivery system and is attached to a delivery cable. It is advanced to the tip of the access sheath, and the sheath is withdrawn. The device deployment follows this. TEE and fluoroscopy guide the device implantation with TEE playing a critical role in determining the adequacy of the device employment. It is then released if the required TEE and fluoroscopic measurements are met, by the counterclockwise rotation of the delivery cable.[44]  

Amplatzer Cardiac Plug and Amulet 

The landing zone is estimated between 12 mm to 15 mm from the LAA orifice both for ACP and Amulet.[45] The 12 Fr to 14 Fr double-curved delivery sheath is introduced into the LAA from the right femoral vein through a transseptal puncture. Post-procedural antiplatelet therapy is recommended for ACP for 1-6 months without OACs, and following it, aspirin is given indefinitely.[45] It is best to avoid appendages with more than 40 mm diameter, lobes behind the pulmonary artery, and posterior orientation of LAA.  

Lariat 

Cardiac CT determines the anatomic eligibility for the procedure. A second-generation device is larger and allows appendages up to 45 mm in diameter. The procedure requires an intact pericardium, hence it cannot be performed in patients with prior cardiac surgery. It is also discouraged in patients with prior pericarditis as the pericardial adhesions may prevent manipulation in the pericardial space and impede procedural success. Using an epidural or micropuncture needle under fluoroscopic guidance, a 14-Fr, slightly curved, and the soft-tipped sheath is advanced into the anterior pericardial space. Using the standard technique, after pericardial access is created, a transseptal sheath of 8.5-Fr is inserted into the LA from the right femoral vein; an inferoposterior location is usually favored in the interatrial septum. Through the transseptal sheath, a magnet-tipped guidewire is progressed into the anterior portion of the LAA, and a complementary magnet-tipped guidewire is progressed through the pericardial sheath and attached to the magnet-tipped wire in the LAA, forming a rail upon which the snare is delivered. TEE and fluoroscopy guide the snare advancement into the pericardial sheath and over LAA, and LAA ostium is closed later. The snare is composed of a preloaded and tied surgical suture. Using a suture-tensioning device, the operator releases the suture with a proximal actuator and then tightens the prettied knot, after which the snare is withdrawn, and the suture is cut using a suture cutter. The pericardial sheath is substituted for a drain and remains in place for 4 to 6 hours, at least. The procedure can be summarized into four steps: Pericardial and transseptal puncture, endocardial magnet-tipped wire advancement into LAA apex, endocardial and epicardial magnet-tipped guidewires connection over which the Lariat snare is advanced, and the snare positioning and LAA ostium capture with the help of TEE-guided placement of inflated EndoCATH balloon catheter, and subsequently LAA suture ligation.[46]  

WaveCrest 

The WaveCrest is positioned to occlude the LAA, and its position is tested to confirm adequate seal and lack of a peri-device leak. The anchors are subsequently deployed to the distal edge of the device in a separate step. The "tug test" is subsequently performed to confirm the stability of the device before the device is released. Advantages include more flexibility while closing the LAA regardless of its depth, and less traumatic deployment.[47]

The most common complications are pericardial effusion or cardiac tamponade requiring intervention, device-related thrombus, device embolization, persistent atrial septal defect (ASD), cardiac perforation, and procedure-related stroke. The incidence of pericardial effusion/tamponade is about 1.2% to 5% and, in the majority of cases, is managed with pericardiocentesis.[25][48][24][49][50][51][52][53][29][54] The incidence of device embolization has been reported as high as 3.5%, requiring transcatheter removal or surgery. However, the incidence is much lower amongst experienced operators (much less than 1%).[25][48][24][49][51][52][53][29][54] Device related thrombus can be encountered in up to 14% of patients and is managed with a longer course of anticoagulation with a success rate approaching 95% (median treatment duration of 45 days).[55][48][51][52][53][29] The majority of these patients are asymptomatic, with an overall incidence of neurological events attributed to device-associated thrombus being very low (0.28%).[55] Persistent ASD incidence accounts for about 11% at six months and 7% at 12 months post-procedure.[56] Usually, ASD is small and does not require treatment. Cardiac perforations occur in up to 0.4% of patients and require surgical intervention.[25] Up to 1.1% of patients develop procedure-related stroke requiring management.[25][48][24][50][51][52][53][54] Other less common complications are procedure-related death, and vascular complications such as hematoma, bleeding, and AV fistula formation.   

Clinical outcomes have been tested in various studies. Clinical efficacy and safety of the Watchman device have been evaluated in two randomized controlled trials (RCTs) and various large registries, demonstrating consistent improvements in procedural successes and complication rates. The PROTECT-AF trial and PREVAIL compared the WATCHMAN device and anticoagulation in patients with AF. The PROTECT-AF trial showed a procedural failure rate of 9%, with procedural-related complications of 8.7%, mostly secondary to pericardial effusion (4.8%).[24] This resulted in a high rate of primary safety events in the Watchman group compared to the anticoagulation group with Rate Ratio (RR) of 1.69, 95% confidence interval (CI) of 1.01-3.19. The mean follow-up was 18 months. The primary endpoint was a stroke, systemic embolism, or cardiovascular death, which occurred in 3% in the study group versus 4.9% in control (RR-0.62, 95% credible interval, 0.35-1.25). Hemorrhagic strokes were less in the WATCHMAN group, as well as a reduction in the composite endpoint of death or disabling stroke in the device arm (RR-0.41, 95% CI, 0.22-0.82). There was about 60%, 34%, and 85% reduction in cardiovascular death (RR-0.4, 95% CI, 0.21-0.75), all-cause mortality (RR-0.66, 95% CI, 0.45-0.98) and hemorrhagic stroke (RR-0.15, 95% CI, 0.03-0.49). Subsequently, PREVAIL trial conducted on 407 patients showed a significant drop in procedure-related complications, even though it contained higher-risk patients, and about 40% of operators were novices.[25] It compared OAC-eligible patients with WATCHMAN device versus warfarin. The results showed a seven-day safety event rate of 2.2% in the Watchman group and also a substantial reduction in serious procedural-related complications rate (4.2%, p = 0.004). Mean follow-up was for 12 months and the non-inferiority criterion was not achieved for the first coprimary efficacy endpoint (stroke, systemic embolism, and cardiovascular death), but was achieved for the second coprimary endpoint (a stroke or systemic embolism greater than seven days; 0.02353 versus 0.02000 (risk difference, 0.0053; 95% credible interval, -0.0190 to 0.0273). Two large registries, the European EWOLUTION registry, and the post-FDA approval US experience included 1021 and 3822 patients, respectively. They demonstrated technical success rates of greater than 95% and significantly low rates of serious adverse effects within 7 days post-procedure.[54][52] Complication rates of serious pericardial effusion were 0.3% and 1.0%, respectively, with less than 0.5% of procedure-related stroke, embolization of device, and procedure-related death rates.  

ACP was first studied in 2011, demonstrating procedural success rates of 96% and serious adverse effects of 7%, of which 3.5% were pericardial effusion.[45] Another report from the largest multicenter registry studying 1047 patients showed a high procedural success rate of 97.3% with serious adverse effects rate of 5%, of which cardiac tamponade and major bleeding accounted for 1.2%, ischemic stroke for 0.9%, and device embolization and procedural-related death of 0.8%.[57] Another prospective study of the Amulet device studied 1088 patients. It demonstrated technical success rates of 99% and procedural or in-hospital complication rates of 3.2%, of which pericardial tamponade accounted for 1.2%, procedure-related death of 0.2%, an ischemic stroke of 0.2%, and device embolization of 0.1%.[58] Another large observational registry with 500 patients showed device repositioning and left ventricular dysfunction associated with a higher number of serious adverse effects.[59] 

In patients with LAA anatomies unsuitable for endocardial devices, Lariat is a great option, although the safety of the procedure is still a concern. There are many studies with the use of a Lariat device.[60][61][62][63][64][65] Results of a retrospective safety registry with 154 patients showed a high technical success rate of 94%.[60] However, major complications occurred in about 10%, significant pericardial effusion rate-10%, major bleeding rate-9%, and emergency surgery requirement-2% of the patients. Given high procedural complication rate, including death, have made Lariat confine to off-label use for LAAC based on FDA safety advisory recommendations. In another large series of Lariat device in 712 patients showed a success rate of greater than 95% and complication rates of 5.3%, which was lower when compared to the prior studies. Complication rates were as follows: procedure-related death-0.1%, cardiac perforations requiring surgery-1.4%, and cardiac perforations not requiring surgery-2%. This decrease in cardiac perforation risk was due to the use of micropuncture needle during pericardial access.

For AF patients, percutaneous LAAC has emerged as a valid alternative to OAC. Although randomized control trials have mostly been restricted to patients who can tolerate short term OAC, registries have shown some benefit in patients at high risk of stroke and with intolerance and/or contraindications to OAC, with consistent improvements in safety as well as long-term efficacy of the procedure. Current recommendations from professional societies support the use of percutaneous LAAC in AF patients with high stroke risk and contraindication for long-term anticoagulation.[Level 1] Guidelines recommend 6 weeks of oral anticoagulation plus aspirin followed by aspirin plus clopidogrel up to 6 months post-procedure. Aspirin will subsequently be continued for the lifetime of the patient.[20][66] However, the post-procedural antithrombotic regimens are sometimes modified in select patients(especially in patients with recurrent bleeding after LAAC) to balance the risk of bleeding and device-associated thrombus. Patients undergo a transesophageal echocardiogram at 6 weeks to confirm adequate sealing of LAA and to rule out device-related thrombus, as this might change the duration of oral anticoagulation. An interprofessional team including an interventional cardiologist, non-invasive cardiologist, specialized in multimodality imaging, cardiac anesthesiologist, nurses, and catheterization laboratory technologists work together to provide an integrated and holistic approach to pre-procedural planning, intra-procedural support, and post-procedural care to ensure an optimal outcome for the patient. Communication, shared decision making, and collaboration between the interprofessional team members are key for excellent outcomes. Interprofessional care also helps identify early and late complications of percutaneous LAAC and therefore improves the prognosis of the patients.