Feasibility of Left Atrial Appendage Occlusion Without Preprocedural Transesophageal Echocardiography or CT Scanning

Abstract: Objective. To assess the success rate and safety outcomes of left atrial appendage occlusion (LAAO) procedures in a cohort of patients who had not undergone preprocedural imaging. Background. LAAO patients usually undergo imaging with either transesophageal echocardiography (TEE) or computed tomography (CT) prior to the procedure itself. This preprocedural imaging may not be necessary. Methods. The procedural success and major complication rates were assessed in a cohort of 52 patients who underwent LAAO without preprocedural imaging. Results. Mean patient age was 75 ± 8 years. Median CHA₂DS₂-VASc score was 4 and median HASBLED score was 3. The LAAO procedure was successful in 51/52 cases (98.1%). In 1 case, the LAAO procedure did not proceed because the LAA was too large for the available occlusion devices. No patient had left atrial appendage thrombus, despite the fact that only 4 patients were taking oral anticoagulation therapy at the time. Major complications occurred in 2/52 cases (3.8%), both due to vascular injuries causing pseudoaneurysm formation. Conclusion. LAAO in this series was not adversely affected by lack of preprocedural imaging. Omitting preprocedural imaging reduces risk attributable to the modality, reduces patient inconvenience and discomfort, reduces cost, and does not appear to significantly reduce the proportion of patients who can undergo a successful procedure. Further larger studies are warranted.

 J INVASIVE CARDIOL 2015;27(12):E297-E301. Epub 2015 October 15.

Key words: cardiac imaging, atrial fibrillation, left atrial appendage occlusion

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Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia, affecting between 1%-2% of the population.^1,2 The incidence of AF increases with age and affects up to 15% of the population by the age of 80 years.^1-3 AF is an independent risk factor for ischemic stroke⁴ and is responsible for up to 1 in 5 strokes.^5,6 Oral anticoagulation (OAC) therapy reduces the risk of ischemic stroke in high-risk patients with AF.⁷ However, OAC therapy carries an associated risk of major hemorrhage and is contraindicated or not tolerated in some patient groups. 

Percutaneous left atrial appendage occlusion (LAAO) is an alternative means of stroke prevention for patients with AF in whom OAC therapy is contraindicated. Studies indicate that successful occlusion of the LAA results in a marked reduction in stroke rates compared with the expected rates based on the patient’s stroke risk score.⁸ The PROTECT-AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation) study proved therapeutic non-inferiority for stroke prevention with LAAO compared with OAC therapy for patients with AF and CHA₂DS₂-VASc score ≥1.^9-11

One of the major challenges of the procedure is accurately sizing the LAA and making the correct choice of an appropriately sized occlusion device. Additionally, patients who cannot tolerate OAC are at risk of developing LAA thrombus. Current practice routinely involves preprocedural imaging either with transesophageal echocardiography (TEE) or a cardiac computed tomography (CT) scan undertaken prior to the patient’s admission for the LAAO procedure. Preprocedural imaging aims to exclude LAA thrombus and define the anatomy of the LAA to guide device size choice.¹² Periprocedural imaging is also achieved during the procedure itself using fluoroscopy and TEE to guide the procedure and to ensure appropriate device deployment and stability. 

It has been our contention from the outset that preprocedural TEE or CT may not be necessary, may only identify a small number of patients with adverse findings, and may raise more questions than it answers with incidental findings of unknown significance. A small case series has previously demonstrated that ad hoc LAAO can be successfully undertaken in a cohort of patients with AF undergoing coronary angiography, without preprocedural imaging of the LAA and using only fluoroscopy during the procedure.¹³

We present a larger cohort of patients who have undergone LAAO without preprocedural imaging of the LAA. LAA morphology assessment and device sizing was undertaken via both TEE and fluoroscopy during the procedure itself. We aim to establish the success rate of LAAO without preprocedural imaging and assess whether this obviates the need for the routine use of preprocedural imaging for LAAO. 

Methods

Study population. We assessed patients prospectively who underwent LAAO between March 2010 and October 2014. The inclusion criteria were AF with a CHA₂DS₂-VASc score ≥1 and a contraindication to OAC therapy. Fifty-four patients underwent LAAO during this time period. Two patients from referring centers had undergone preprocedural TEEs at the request of the referring doctor and were therefore excluded from this analysis. 

Device. For all patients, either the Amplatzer Cardiac Plug (ACP) or the Amplatzer Cardiac Plug 2 (Amulet; St. Jude Medical) was used for the LAAO procedure. In all patients, periprocedural TEE and fluoroscopy were used to assess LAA morphology, presence or absence of LAA thrombus, and LAA size and dimensions. The risk of undersizing is device embolization; the risk of oversizing is compression on the left circumflex and/or left superior pulmonary vein, as well as LAA perforation and device embolization. Figure 1 shows how TEE was used to measure the LAA ostium, LAA neck (landing zone), and LAA depth. The landing zone is measured in a perpendicular plane to the lie of the appendage, from the base of the circumflex coronary artery to a point 10 mm distal to the limbus of the left superior pulmonary vein in the 120° TEE view, and similarly using quantitative angiography in the right anterior oblique cranial or right anterior oblique views (Figure 2). Periprocedural TEE and fluoroscopy were also used to visualize device insertion and deployment (Figures 3 and 4).

LAAO success. Procedural success was based on the fluoroscopic and echocardiographic appearance post device deployment. The procedure was deemed successful if TEE and fluoroscopy indicated the device to be appropriately positioned with good stability, compression of the lobe, and absent or minimal flow between the left atrium and the LAA. The major complication rate was also assessed. Device embolization, pericardial effusion requiring drainage, cardiac tamponade, major bleeding events, and procedure-related stroke were all considered to be major complications. Other complications were also recorded. Patients were followed up once at 3 months after their procedure, then discharged back to their primary physician.

Results

Patient demographics. Baseline patient characteristics are summarized in Table 1. Thirty-three out of 52 patients (63.5%) were male. Mean age was 74.9 years (age range, 55-90 years). The median CHA₂DS₂-VASc score was 4, conferring an estimated ischemic stroke rate of 9.3% per year without OAC. The median HASBLED score was 3, conferring a risk of 3.74 major bleeds per 100 patient years.¹⁴ Forty-two out of 52 patients (80.8%) had permanent AF and 10 out of 52 patients (19.2%) had paroxysmal AF. 

The most common reason for LAAO in the patient cohort was a previous major bleed on OAC therapy in 27 out of 52 patients (51.9%). Nineteen out of 52 patients (36.5%) underwent LAAO, as they were unable to receive OAC therapy due to bleeding risk. Three out of 52 patients (5.8%) underwent LAAO due to intolerance of OAC therapy. A further 3 out of 52 patients (5.8%) underwent LAAO due to patient preference.

Device insertion and LAAO success. In all cases, the periprocedural imaging via TEE and fluoroscopy provided a maximum and minimum size of the LAA os once mean left atrial pressure of 10 mm Hg was achieved with intravenous fluid administration. The ACP device was used for 48 cases (92.3%) and the Amulet for 4 cases (7.7%). In 51 cases (98.1%), the ACP or Amulet was successfully deployed within the LAA with acceptable fluoroscopic and echocardiographic closure parameters to indicate successful LAA closure. In 1 case, the LAAO procedure did not proceed because the LAA was too large (36 mm landing zone) for the available occlusion devices (16-30 mm ACP). No patient had the procedure deferred or canceled because of LAA clot, despite the fact that most patients (48 out of 52) were not on formal OAC leading up to the procedure. 

Of the successful LAAO cases, the device size varied from 16-30 mm. The most commonly used device size was 26 mm ACP, which was used in 11 of the 51 successful cases (21.6%). In 5 of the 51 successful cases (9.8%), two LAAO devices were used. This was due to incomplete or unacceptable closure parameters on deployment of the first device, resulting in withdrawal of this device and deployment of a different-sized device. All 5 cases where two devices were used ultimately resulted in successful LAAO.

Major complications were reported in 2 out of 52 cases (3.8%), both of which were related to major bleeding events. In these 2 cases, both patients were found to have femoral pseudoaneurysms after the procedure due to presumed inadvertent additional arterial puncture. In both cases, the pseudoaneurysms were successfully repaired surgically.  

Patients in this study were followed up once at 3 months post LAAO procedure. None of the patients who underwent LAAO had a subsequent stroke. One patient with known cerebrovascular disease had a transient ischemic attack 6 months after Amplatzer implantation. At that stage, he underwent TEE, which showed that the device was clear of thrombus.

Discussion

This study demonstrates that LAAO can be safely and effectively undertaken without preprocedural TEE or CT. There was an LAAO success rate of 98.1% in patients in this cohort, none of whom underwent any preprocedural imaging, indicating that periprocedural imaging provides enough information to appropriately delineate the anatomy of the LAA and accurately size the defect and required occlusion device. Omitting preprocedural imaging reduces the inconvenience and additional risks of these imaging modalities to patients. The risks of additional preprocedural TEE include esophageal trauma or perforation, dental injuries, vocal cord damage, and gastrointestinal bleeding. The risks of preprocedural cardiac CT include exposure to high levels of ionizing radiation and complications relating to intravenous contrast (anaphylaxis and contrast nephropathy). Omitting preprocedural imaging also reduces the cost of LAAO, as both TEE and cardiac CT are expensive imaging modalities. This study builds on an earlier study, which demonstrated that ad hoc LAAO in patients with AF undergoing coronary angiography could be safely undertaken without preprocedural imaging using periprocedural fluoroscopy alone.¹³ In our larger study, we demonstrated that combining periprocedural fluoroscopy with periprocedural TEE in patients undergoing LAAO provided safe and effective LAA assessment, resulting in successful LAAO.

The first trial that compared LAAO to OAC therapy as a means of stroke prevention was the PROTECT-AF trial. This trial observed an LAAO success rate of 91%.^9-10 Subsequent trials have demonstrated higher LAAO success rates of 95%-100%.¹⁵ The LAAO success rate in our study was 98.1%, which is similar to other studies, indicating that the omission of preprocedural imaging does not have an obvious negative impact on LAAO procedural success rate.

The PROTECT-AF trial observed a major complication rate of 7.4 events/100 patient-years in patients who underwent LAAO.^9,10 Other subsequent studies have identified lower major LAAO complication rates of 4%-4.4%.¹⁵ In the current study, the major complication rate was 3.8%, which is similar to other studies, again indicating that the omission of preprocedural imaging does not seem to negatively impact the procedural complication rate. Given that both major complications in this study were bleeding events related to femoral vein vascular access, it is unlikely that these would have been avoided with the addition of preprocedural imaging of the LAA with either TEE or cardiac CT. The occurrence of inadvertent arterial puncture in this series suggests that routine ultrasound assessment of the femoral vascular bed might be a useful clinical tool, as has been described elsewhere.¹⁶

The anatomy and sizing of the LAA is without doubt essential to successful LAAO. It has previously been suggested that morphology and sizing of the LAA via different imaging modalities (TEE, planar cardiac CT, and three-dimensional cardiac CT) are not interchangeable and that more extensive imaging with cardiac CT might improve LAAO device sizing.¹⁷ In the current study, we demonstrate that there is no obvious additional benefit to extensive preprocedural imaging by assessing the outcomes of the procedure (success rate and complications) in the absence of preprocedural imaging.

Preprocedural imaging also has inherent risks. In addition, we feel that simplifying the pathway by which patients can undergo LAAO by omitting preprocedural imaging will reduce the cost and waiting times for this procedure, making this more accessible to the large number of patients who require stroke prevention but are unable to tolerate OAC therapy. In the longer term, it is hoped that improving access to LAAO procedures will reduce morbidity and mortality from AF-related strokes in these patients who are unable to have OAC therapy and thereby reduce health-care costs.

It is important to note that the main limitation of undertaking LAAO without preprocedural imaging is the chance of an unexpected finding, such as thrombus in the LAA or finding an unusually small or large appendage that is anatomically complex. Such findings may result in the LAAO not proceeding. Alternatively, if the patient has had previous surgery, it is possible that the appendage has been previously removed. Patients who have had previous cardiothoracic surgery should therefore, in our view, undergo imaging before the procedure.

Conclusion

LAAO can be safely and effectively undertaken without preprocedural imaging. Procedural success is not adversely affected. The omission of preprocedural imaging reduces risk attributable to the modality, patient discomfort, and cost, and does not significantly reduce the proportion of patients who can undergo a successful procedure. 

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From the Sussex Cardiac Centre, Brighton and Sussex University Hospitals NHS Trust, Brighton, United Kingdom. 

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Hildick-Smith reports proctoring fees from St. Jude Medical. The remaining authors report no conflicts of interest regarding the content herein.

Manuscript submitted April 16, 2015, provisional acceptance given May 12, 2015, final version accepted July 16, 2015.

Address for correspondence: David Hildick-Smith, MD, MRCP, Royal Sussex Cardiac Centre, Brighton Department of Cardiology, Brighton, BN2 5BE, United Kingdom. Email: david.hildick-smith@bsuh.nhs.uk