Application of cardiac computed tomographic imaging and fluoroscopy fusion for guiding left atrial appendage occlusion

Efficiency of optimal fluoroscopic projection angle defined by computed tomography angiography for left atrial appendage closure

BACKGROUND

Left atrial appendage (LAA) closure (LAAC) procedures are conventionally performed using empirical fluoroscopic viewing angles. However, because the LAA is a highly variable anatomical structure, these angles cannot depict the LAA in the optimal position. The present study aimed to assess the efficiency of using a novel optimal fluoroscopic projection angle (OPA) for LAAC and to validate its feasibility.

METHODS

The OPAs of the derivation cohort were acquired using cardiac computed tomography angiography (CCTA) to assess its superiority for depicting LAA depth versus traditional working angles (TAs) of RAO 30°, CAU 20°. The practicability of OPA-guided LAAC was demonstrated by comparison between clinical data from the validation cohort and those from a propensity-score matched (PSM) control group, as well as randomized controlled studies investigating LAAC.

RESULTS

Of 705 patients in the derivation cohort, the median OPA was RAO 46°, CAU 31°. Compared with TA, the OPA depicted a longer mean (±SD) LAA depth (5.1 ± 4.4) mm and a larger orifice diameter (1.1 ± 1.1 mm), (P < 0.0001 for both). All 38 OPA-guided LAACs were successful, with a shorter mean procedure duration (42.9 ± 12.3 min versus [vs.] 107.2 ± 41.5 min; P < 0.0001) and reduced device consumption (1.08 vs. 1.5 per case), compared with the PSM control group. At the 3-month follow-up, the incidence of peri-device leak was 52.6% (20/38) detected by CCTA, with a mean leakage of 1.6 ± 0.8 mm.

CONCLUSION

By unfolding the LAA depth and orifice diameter for a better view, OPA demonstrated the potential to optimize LAAC procedural efficiency, although further larger-scale studies are required to confirm this.

Peri-device leakage and delayed endothelialization of the Watchman device: a computed tomography study

OBJECTIVES

This study aimed to explore the endothelialization process and assess the potential association between endothelialization and peri-device leak (PDL) following Watchman implantation via a quantitative method.

METHODS

This is a single-center retrospective study of consecutive patients undergoing LAAO between December 2015 and November 2021. Device endothelialization, compared between PDL and non-PDL group, were quantitatively analyzed based on hypoattenuated thickening in cardiac computed tomography angiography (CCTA). Advancement in endothelialization over time were explored using the Cochran-Armitage test and generalized estimating equation approach. Potential risk factors of delayed endothelialization were analyzed using the Cox proportional-hazards model.

RESULTS

A total of 172 patients (mean age, 68 years ± 10 [standard deviation], 114 men) were finally included. The average endothelialization ratio of the study population was 89.8 ± 7.2 percent. In the follow-up period of postprocedural 3 months to more than 12 months, an incremental trend of endothelialization over time was observed with the ratio of 85.8 ± 8.0, 89.6 ± 7.6, 92.2 ± 4.5, 94.3 ± 2.9 percent, respectively (p < 0.0001). Notably, patients without PDL exhibited a swifter advancement in endothelialization compared to those with PDL, irrespective of device size. The multivariable Cox regression model showed that PDL (HR = 2.113, 95%CI: 1.300-3.435, p = 0.003), DSP (HR = 1.717, 95%CI: 1.113-2.647, p = 0.014) were independent risk factors of delayed endothelialization.

CONCLUSION

CCTA holds promise as an effective means of quantitatively assessing device endothelialization. Endothelialization advanced gradually over time, with PDL potentially impeding device endothelialization.

CLINICAL RELEVANCE STATEMENT

A comprehensive understanding of the correlation between endothelialization ratio, time, and residual shunt can establish a more dependable foundation for determining the appropriate anticoagulation treatment following left atrial appendage closure.

KEY POINTS

Current recommendations for postleft atrial appendage occlusion anti-platelet and anticoagulation therapy are based on animal studies. Cardiac computed tomography angiography (CCTA) combined with the UNet neural network model enables the quantitative assessment of device endothelialization. This technique will allow for additional studies to better understand device endothelialization to optimize treatments in this population.

Minimalistic approach to left atrial appendage occlusion guided by cardiac computed tomography angiography

OBJECTIVE

To assess the feasibility and safety of the minimalistic approach to left atrial appendage occlusion (LAAO) guided by cardiac computed tomography angiography (CCTA).

METHODS

Ninety consecutive patients who underwent LAAO, with or without CCTA-guided, were matched (1:2). Each step of the LAAO procedure in the computed tomography (CT) guidance group (CT group) was directed by preprocedural CT planning. In the control group, LAAO was performed using the standard method. All patients were followed up for 12 months, and device surveillance was conducted using CCTA.

RESULTS

A total of 90 patients were included in the analysis, with 30 patients in the CT group and 60 matched patients in the control group. All patients were successfully implanted with Watchman devices. The mean ages for the CT group and the control group were 70.0 ± 9.4 years and 68.4 ± 11.9 years (P = 0.52), respectively. The procedure duration (45.6 ± 10.7 min vs. 58.8 ± 13.0 min, P < 0.001) and hospital stay (7.5 ± 2.4 day vs. 9.6 ± 2.8 day, P = 0.001) in the CT group was significantly shorter compared to the control group. However, the total radiation dose was higher in the CT group compared to the control group (904.9 ± 348.0 mGy vs. 711.9 ± 211.2 mGy, P = 0.002). There were no significant differences in periprocedural pericardial effusion (3.3% vs. 6.3%, P = 0.8) between the two groups. The rate of postprocedural adverse events (13.3% vs. 18.3%, P = 0.55) were comparable between both groups at 12 months follow-up.

CONCLUSIONS

CCTA is capable of detailed LAAO procedure planning. Minimalistic LAAO with preprocedural CCTA planning was feasible and safe, with shortened procedure time and acceptable increased radiation and contras consumption. For patients with contraindications to general anesthesia and/or transesophageal echocardiography, this promising method may be an alternative to conventional LAAO.

Multi-network approach for image segmentation in non-contrast enhanced cardiac 3D MRI of arrhythmic patients

Left atrial appendage (LAA) is the source of thrombi formation in more than 90% of strokes in patients with nonvalvular atrial fibrillation. Catheter-based LAA occlusion is being increasingly applied as a treatment strategy to prevent stroke. Anatomical complexity of LAA makes percutaneous occlusion commonly performed under transesophageal echocardiography (TEE) and X-ray (XR) guidance especially challenging. Image fusion techniques integrating 3D anatomical models derived from pre-procedural imaging into the live XR fluoroscopy can be applied to guide each step of the LAA closure. Cardiac magnetic resonance (CMR) imaging gains in importance for radiation-free evaluation of cardiac morphology as alternative to gold-standard TEE or computed tomography angiography (CTA). Manual delineation of cardiac structures from non-contrast enhanced CMR is, however, labor-intensive, tedious, and challenging due to the rather low contrast. Additionally, arrhythmia often impairs the image quality in ECG synchronized acquisitions causing blurring and motion artifacts. Thus, for cardiac segmentation in arrhythmic patients, there is a strong need for an automated image segmentation method. Deep learning-based methods have shown great promise in medical image analysis achieving superior performance in various imaging modalities and different clinical applications. Fully-convolutional neural networks (CNNs), especially U-Net, have become the method of choice for cardiac segmentation. In this paper, we propose an approach for automatic segmentation of cardiac structures from non-contrast enhanced CMR images of arrhythmic patients based on CNNs implemented in a multi-stage pipeline. Two-stage implementation allows subdividing the task into localization of the relevant cardiac structures and segmentation of these structures from the cropped sub-regions obtained from previous step leading to efficient and effective way of automated cardiac segmentation.

The impact of contrast retention on thrombus formation risks in patients with atrial fibrillation: A numerical study

Background

Contrast retention (CR) is an important predictor of left atrial appendage thrombus (LAAT) and stroke in patients with non-valvular atrial fibrillation (AF). We sought to explore the underlying mechanisms of CR using computational fluid dynamic (CFD) simulations.

Methods

A total of 12 patients with AF who underwent both cardiac computed tomography angiography (CTA) and transesophageal echocardiography (TEE) before left atrial appendage occlusion (LAAO) were included in the study. The patients were allocated into the CR group or non-CR group based on left atrial appendage (LAA) angiography. Patient-specific models were reconstructed to evaluate time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and endothelial cell activation potential (ECAP). Additionally, the incidence of thrombosis was predicted using residence time (RT) at different time-points.

Results

TAWSS was lower [median (Interquartile Range) 0.27 (0.19-0.47) vs 1.35 (0.92-1.79), p < 0.001] in LAA compared to left atrium. In contrast, RRT [1438 (409.70-13869) vs 2.23 (1.81-3.14), p < 0.001] and ECAP [122.70 (30.01-625.70) vs 0.19 (0.16-0.27), p < 0.001)] was higher in the LAA. The patients in the CR group had significantly higher RRT [(mean ± SD) 16274 ± 11797 vs 639.70 ± 595.20, p = 0.009] and ECAP [610.80 ± 365.30 vs 54.26 ± 54.38, p = 0.004] in the LAA compared to the non-CR group. Additionally, patients with CR had a wider range of thrombus-prone regions [0.44(0.27-0.66)% vs 0.05(0.03-0.27)%, p = 0.009] at the end of the 15th cardiac cycle.

Conclusions

These findings suggest that CR might be an indicator of high-risk thrombus formation in the LAA. And CT-based CFD simulation may be a feasible substitute for the evaluation of LAA thrombotic risk in patients with AF, especially in patients with CR.

Preprocedural Planning of Left Atrial Appendage Occlusion: A Review of the Use of Additive Manufacturing

Stroke is a significant public health problem, with non-valvular atrial fibrillation (NVAF) being one of its main causes. This cardiovascular arrhythmia predisposes to the production of intracardiac thrombi, mostly formed in the left atrial appendage (LAA). When there are contraindications to treatment with oral anticoagulants, another therapeutic option to reduce the possibility of thrombus formation in the LAA is the implantation of an occlusion device by cardiac catheterization. The effectiveness of LAA occlusion is dependent on accurate preprocedural device sizing and proper device positioning at the LAA ostium, to ensure sufficient device anchoring and avoid peri-device leaks. Additive manufacturing, commonly known as three-dimensional printing (3DP), of LAA models is beginning to emerge in the scientific literature to address these challenges through procedural simulation. This review aims at clarifying the impact of 3DP on preprocedural planning of LAA occlusion, specifically in the training of cardiac surgeons and in the assessment of the perfect adjustment between the LAA and the biomedical implant.

Real-time 3D-3D image fusion of CTA/CBCT roadmap fluoroscopy in the transcatheter mitral intervention

Absence of periprocedural visualization of three-dimensional (3D) left heart anatomy and its surrounding structures in fluoroscopy may reduce the rate of successful transcatheter mitral valve repair. We proposed a multimodal imaging strategy based on 3D computed tomography (CT) angiography and 3D cone beam CT fusion images, which enabled real-time visual inspection of 3D cardiac structures on fluoroscopy, to optimize transcatheter mitral intervention. This new image fusion technology, together with standard transesophageal echocardiography guidance, improved the efficiency and safety of the procedure, and could be considered as a new workflow for transcatheter mitral valve intervention.

Efficacy of 3D-multidetector computed tomography and fluoroscopy fusion for percutaneous left atrial appendage occlusion procedures

INTRODUCTION

We studied the impact of the use of three-dimensional multidetector computed tomography (3D-MDCT) and fluoroscopy fusion on percutaneous left atrial appendage occlusion (LAAO) procedures in relation to procedure time, contrast volume, fluoroscopy time, and total radiation.

METHODS

This was a single-center, prospective, single-blinded, randomized control trial. Patients meeting criteria for LAAO were randomized to undergo LAAO with the WATCHMAN FLXTM device with and without 3D-MDCT-fluoroscopy fusion guidance using a prespecified protocol using computed tomography angiography for WATCHMAN FLXTM sizing, moderate sedation, and intracardiac echocardiography for procedural guidance.

RESULTS

Overall, 59 participants were randomly assigned to the fusion (n = 33) or no fusion (n = 26) groups. The median (interquartile range) age was 79 (75-83) years, 24 (41%) were female, and 55 (93%) were Caucasian. The median CHA2 DS2 VASc and HASBLED scores were 5 (4-6) and 3 (3-4), respectively. At the time of the study, 51 (53%) patients were on a direct acting oral anticoagulant. There were no significant differences between the fusion and no fusion groups in procedure time (52.4 ± 15.4 vs. 56.8 ± 19.5 min, p = .36), mean contrast volume used (33.8 ± 12.0 vs. 29.6 ± 11.5 mls, p = .19), mean fluoroscopy time (31.3 ± 9.9 vs. 28.9 ± 8.7 min, p = .32), mean radiation dose (1177 ± 969 vs. 1091 ± 692 mGy, p = .70), and radiation dose product curve (23.9 ± 20.5 vs. 35.0 ± 49.1 Gy cm2 , p = .29). There was no periprosthetic leak in the two groups in the immediate 1-month postprocedure follow-up periods.

CONCLUSIONS

There was no significant difference with and without 3D-MDCT-fluoroscopy fusion in procedure time, contrast volume use, radiation dose, and radiation dose product.

Feasibility and safety of the direct current cardioversion at the time of left atrial appendage occlusion for patients with atrial fibrillation

Background

With an increasing number of patients undergoing left atrial appendage occlusion (LAAO), more attention is being paid to relieving clinical symptoms and improving the quality of life of these patients. For patients with atrial fibrillation (AF), direct current cardioversion (DCCV) is an alternate, nonpharmacological choice to restore sinus rhythm and relieve clinical symptoms.

Objectives

The purpose of this study was to assess the feasibility and safety of the DCCV at the time of LAAO for patients with AF.

Methods

Forty patients were enrolled in the DCCV group undergoing the DCCV at the time of LAAO. The control group undergoing LAAO alone was formed by 1:1 matching.

Results

In the DCCV group, cardioversion was immediately successful in 30 (75%) patients, of which 12 (40%) had AF recurrence at the three-month follow-up. The failed-DCCV group was older (73.70 ± 4.74 vs. 62.20 ± 9.01 years old, P = 0.000), had a faster postcardioversion heart rate (88.80 ± 16.58 vs. 70.97 ± 14.73 times, P = 0.03), and had a higher mean HAS-BLED score (4.00 vs. 3.00, P = 0.01) than the successful-DCCV group. No patients experienced periprocedural pericardial effusion, occluder displacement, device embolism, or >5 mm peridevice leakage. One patient experienced a transient ischemic attack (TIA) in the DCCV group during the follow-up.

Conclusions

The DCCV at the time of LAAO is feasible and safe for AF patients with contraindications for catheter ablation or AF recurrence after previous catheter ablation to restore the sinus rhythm and relieve clinical symptoms. The DCCV at the time of LAAO is more likely to succeed for younger patients and patients with lower HAS-BLED scores.

The Chinese Experience of Imaging in Cardiac Intervention: A Bird's Eye Review

Recent scientific and technological advances have greatly contributed to the development of medical imaging that could enable specific functions. It has become the primary focus of cardiac intervention in preoperative assessment, intraoperative guidance, and postoperative follow-up. This review provides a contemporary overview of the Chinese experience of imaging in cardiac intervention in recent years.

Left Atrial Appendage Occlusion: Current Stroke Prevention Strategies and a Shift Toward Data-Driven, Patient-Specific Approaches

The left atrial appendage (LAA) is a complex structure with unknown physiologic function protruding from the main body of the left atrium. In patients with atrial fibrillation, the left atrium does not contract effectively. Insufficient atrial and LAA contractility predisposes the LAA morphology to hemostasis and thrombus formation, leading to an increased risk of cardioembolic events. Oral anticoagulation therapies are the mainstay of stroke prevention options for patients; however, not all patients are candidates for long-term oral anticoagulation. Percutaneous occlusion devices are an attractive alternative to long-term anticoagulation therapy, although they are not without limitations, such as peri-implant leakage and device-related thrombosis. Although efforts have been made to reduce these risks, significant interpatient heterogeneity inevitably yields some degree of device-anatomy mismatch that is difficult to resolve using current devices and can ultimately lead to insufficient occlusion and poor patient outcomes. In this state-of-the-art review, we evaluated the anatomy of the LAA as well as the current pathophysiologic understanding and stroke prevention strategies used in the management of the risk of stroke associated with atrial fibrillation. We highlighted recent advances in computed tomography imaging, preprocedural planning, computational modeling, and novel additive manufacturing techniques, which represent the tools needed for a paradigm shift toward patient-centric LAA occlusion. Together, we envisage that these techniques will facilitate a pipeline from the imaging of patient anatomy to patient-specific computational and bench-top models that enable customized, data-driven approaches for LAA occlusion that are engineered specifically to meet each patient's unique needs.