Cardiac CT assessment of left atrial accessory appendages and diverticula

A meta-analysis of the accessory left atrial appendage and the left atrial diverticulum

Left atrial (LA) structures, including the accessory left atrial appendage (aLAA) and left atrial diverticulum, have been studied based on their prevalence, shape, and association with arrhythmia and thrombi formation. A pooled prevalence with morphometric data has not been determined in previous research. Our goal is to provide structured, clinically relevant information on said structures for clinical practitioners to use in their daily work. We propose that morphometric data of additional LA structures is necessary when considering the possible complications during cardiac interventions. We conducted a meta-analysis of all relevant studies which used electrocardiogram (ECG)-gated computed tomography (CT) imaging to determine the prevalence of LA structures and record their morphometric characteristics as well as the presence of thrombi. Data were extracted from 19 studies (n = 6643 hearts). The pooled prevalence estimate of left atrial diverticulum and/or aLAAs were reported from 14 studies and was 28.8%. The most common location noted was anterosuperior in the LA with 70.2% of structures found there. Data regarding thrombi presence in left atrial diverticulums or aLAAs were extracted from 11 studies and a thrombus was present in 0.2%. The prevalence rates of aLAAs and left atrial diverticulums are essential in performing uncomplicated cardiac interventions and reducing risk of electrophysiological procedures. Our findings show a considerable prevalence of LA structures in varying populations, provides information regarding the general characteristics of said structures, and does not support the previously theorized associated risk of thrombus formation in relation to LA structure presence.

Left Atrial Diverticula Present in the Right Lower Pulmonary Vein Thrombus Attachment Area

Left atrial diverticula (LADs) are thought to be associated with atrial fibrillation and an ischemic brain state. However, the mechanisms of LAD formation are unknown. Pulmonary vein thrombi (PVTs) can cause acute myocardial infarction (AMI) and ischemic stroke by releasing rather large particles. Additionally, PVTs can release much smaller particles, including neutrophil extracellular traps (NETs) and/or other components of NETs, such as DNA and histones. To treat these diseases, it may be crucial to know the specific traits of PVTs. However, these issues are not direct effects of PVTs on the left atrium (LA). It is unclear whether PVTs affect the LA directly. We checked the direct effects of PVTs on the LA using cardiac computed tomography (CT) and transesophageal echocardiography (TEE). The patient was a 73-year-old female with hypertension. TEE revealed extended LA thrombi from the right lower pulmonary vein, which were attached to the anterosuperior wall of the LA. Cardiac CT revealed the attaching area as a defect of enhancement and dimly revealed LAD with full thrombi on the attaching area. It was difficult to recognize the LAD at first; however, after one month of standard-dose heparin-warfarin treatment, the LAD was clearly detected using cardiac CT. LA thrombi could not be detected using cardiac CT.

Association between pouch morphology, cardiovascular risk factors and ischemic brain lesions in patients with left-sided septal pouches

BACKGROUND

Left atrial outpouching structures such as left atrial diverticula (LADs) and left-sided septal pouches (LSSPs) might be a source of cryptogenic stroke. This imaging study evaluates the association between pouch morphology, patient comorbidities and ischemic brain lesions (IBLs).

METHODS

This is a retrospective single-center analysis of 195 patients who received both a cardiac CT and a cerebral MRI. LADs, LSSPs, and IBLs were retrospectively identified. Size measurements included pouch width, length and volume for LADs and circumference, area and volume for LSSPs. The association between LADs/LSSPs, IBLs and cardiovascular comorbidities was determined by univariate and bivariate regression analyses.

RESULTS

The prevalence and mean volume were 36.4% and 372 ± 569 mm³ for LSSPs, and 40.5% and 415 ± 541 mm³ for LADs. The IBL prevalence was 67.6% in the LSSP group and 48.1% in the LAD group. LSSPs had 2.9-fold increased hazards of IBLs (95%CI: 1.2-7.4, p = 0.024), and LADs showed no significant correlation with IBLs. Size measurements had no impact on IBLs. A co-existing LSSP was associated with an increased prevalence of IBLs in patients with coronary artery disease (HR: 1.5, 95%CI: 1.1-1.9, p = 0.048), heart failure (HR: 3.7, 95%CI: 1.1-14.6, p = 0.032), arterial hypertension (HR: 1.9, 95%CI: 1.1-3.3, p = 0.017), and hyperlipidemia (HR: 2.2, 95%CI: 1.1-4.4, p = 0.018).

CONCLUSION

Co-existing LSSPs were associated with IBLs in patients with cardiovascular risk factors, however, pouch morphology did not correlate with the IBL rate. Upon confirmation by further studies, these findings might be considered in the treatment, risk stratification, and stroke prophylaxis of these patients.

Is there an association between left atrial outpouching structures and recurrence of atrial fibrillation after catheter ablation?

Objective

The aim of this study was to investigate the impact of left atrial diverticula (LADs), left sided septal pouches (LSSPs) and middle right pulmonary veins (MRPVs) on recurrent atrial fibrillation (rAF) in patients undergoing laser pulmonary vein isolation procedure (PVI).

Material and methods

This retrospective study enrolled 139 patients with pre-procedural multiple detector computed tomography (MDCT) imaging and 12 months follow-up examination. LADs, LSSPs and MRPV were identified by two radiologists on a dedicated workstation using multiplanar reconstructions and volume rendering technique. Univariate and bivariate regression analyses with patient demographics and cardiovascular risk factors as covariates were performed to reveal independent factors associated with rAF.

Results

LADs were recorded in 41 patients (29%), LSSPs in 20 (14%) and MRPVs in 15 (11%). The right anterosuperior wall of the left atrium was the most prevalent location of LADs (68%). rAF occured in 20 patients, thereof, 15 exhibited an outpouching structure of the left atrium (LAD: 9, LSSP: 2 and MRPV: 3). Presence of an LAD (HR: 2.7, 95%CI: 1.0–8.4, p = 0.04) and permanent AF (HR: 4.8, 95%CI: 1.5–16.3, p = 0.01) were independently associated with rAF.

Conclusions

LAD, LSSP and MRPV were common findings on pre-procedural cardiac computed tomography. LADs were revealed as potential independent risk factor of rAF, which might be considered for treatment planning and post-treatment observation.

Cardiac CT evaluation of left atrial diverticulum and accessory appendage

Background

The aim of this study was to evaluate the prevalence, location, size, and morphological features of the left atrial accessory appendage and diverticulum with cardiac computed tomography. Cardiac computed tomography obtained consecutively from 1415 patients with normal ECG findings during a 2-year period were analyzed. Left atrial appendage and diverticulum type, location, and size were recorded and analyzed according to age and gender.

Results

Cardiac computed tomography of 1415 (796 males and 619 females) participants aged 44.1 + 12.2 years old were re-evaluated, and 238 atrial diverticulum were found in 234 (16.5%) patients, accessory appendage in 93 (6.5%), and atrial diverticula and accessory appendage together in eight (0.56%) patients. The atrial diverticulum was most frequently observed in the anterosuperior localization (n = 157, 49.2%). One hundred and twenty-three (52%) of the atrial diverticulum were cystic, and 107 (45%) were tubular form. Accessory appendage was observed most frequently in the anterior superior location (n = 65, 20.4%).

Conclusions

The frequency of left atrial diverticulum was found to be 16%, and the frequency of accessory appendage was 6%, consistent with the majority of the literature. Left atrial diverticulum and accessory appendage were detected more frequently in men than in women. Cystic form is more common in left atrial diverticulum.

The use of cardiac computed tomography angiography in the assessment of percutaneous left atrial appendage closure - Review and experts recommendations endorsed by the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle

Atrial fibrillation is the most common cause of arrhythmia which is responsible for over 15% of ischemic strokes, most of these being secondary to migration of a left atrial appendage (LAA) thrombus. In patient with contraindication to anticoagulant therapy, percutaneous closure system placement may be indicated. Cardiac computed tomography (CT) angiography plays a central role in the initial assessment as well as in the follow-up. The purpose of the pre-implantation cardiac CT angiography is to evaluate the anatomy of the LAA in order to select the most suitable prosthesis and check for any contraindication to device implantation. Image analysis is divided into four steps that include analysis of the approach; search for a thrombus in the LAA; investigation of the anatomy of the LAA (morphology of the LAA, dimensions of the LAA and choice of device) and cardiac and thoracic assessments. Follow-up involves CT examination to check for correct placement of the device and to detect any complications. On the basis of the results of currently available published research, a panel of experts has issued recommendations regarding cardiac CT angiography prior to percutaneous LAA closure device placement, which were further endorsed by the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV).

Pre- and Postprocedural CT of Transcatheter Left Atrial Appendage Closure Devices

Transcatheter left atrial appendage (LAA) closure is an alternative to long-term anticoagulation therapy in selected patients with nonvalvular atrial fibrillation who have an increased risk for stroke. LAA closure devices can be implanted by means of either an endocardial or a combined endocardial and epicardial approach. Preprocedural imaging is key to identifying contraindications, accurately sizing the device, and minimizing complications. Transesophageal echocardiography (TEE) has been the reference standard imaging modality to assess the anatomy for LAA closure and to provide intraprocedural guidance. However, CT has emerged as a less-invasive alternative to TEE for pre- and postprocedural imaging. CT is comparable to TEE for exclusion of thrombus but is superior to TEE for the delineation of complex LAA anatomy, measurement for device sizing, and evaluation of pulmonary venous and extracardiac structures. CT provides accurate measurements of the LAA ostial diameter, landing zone diameter, and LAA length, which are vital for accurate sizing of the device. CT allows evaluation of the relationship with the pulmonary veins and other adjacent structures that can be injured during the procedure. CT also simulates procedural fluoroscopic angles and provides evaluation of the interatrial septum, which is punctured during LAA closure. CT also provides a more convenient method for the evaluation of postprocedural complications such as incomplete closure, peridevice leaking, device-related thrombus, and device dislodgement. Online supplemental material is available for this article. ^©RSNA, 2021.

Left Atrial Appendage Morphology and Left Atrial Wall Thickness Are Associated with Cardio-Embolic Stroke

Background. New markers for stroke risk stratification in patients with atrial fibrillation (AF) are on demand. Hence, we aimed to investigate the association of left atrial appendage (LAA) and left atrium (LA) morphological parameters in patients with cardio-embolic (CE) stroke due to AF in comparison to controls without stroke. Methods: A retrospective analysis of cardiac computed tomography angiography (CTA) examinations performed between 2006 and 2017 for clinical indications in 158 patients (median age 65 (54–73) years, 48.7% females) was conducted: 56 patients with CE stroke were compared to 102 controls not differing in gender, body mass index (BMI) and CHA₂DS₂-VASc score. Results: On multivariable regression analysis adjusted for CHA₂DS₂-VASc score and LA diameter CE stroke was independently associated with the following parameters: windsock LAA type (OR 2.55; CI: 1.04–6.26, p = 0.041), a greater lobe number (OR 1.54; CI: 1.13–2.10, p = 0.006), a greater LAA ostium area (OR 1.88; CI: 1.38–2.55, p < 0.001) and a greater left atrium wall thickness (LAWT) in the middle and right part, measured along the anterior LA wall in the axial plane (respectively, OR 1.94; CI: 1.26–3.0, p = 0.003 and OR 1.57; CI: 1.07–2.31, p = 0.021). Conclusions: The windsock LAA type, a greater LAA lobe number, a larger LAA ostium and a greater LAWT are associated with CE stroke. These CTA parameters could improve risk stratification for thromboembolic stroke.

Left atrial diverticula: Innocent bystanders or wolves in sheep's clothing?

INTRODUCTION

The finding of left atria diverticula (LAD) on cardiac computed tomography images obtained from patients with atrial fibrillation (AF) referred for pulmonary vein isolation is not uncommon. Prior studies reporting on LAD do not always provide definitions of LAD resulting in confusion with other anatomical structures such as left atrial accessory appendages (LAAA) and atrial aneurysms. The aim of this review is to identify an accurate definition of LAD and to describe distinctive properties between LAD and other left atrial structures, such as LAAA and aneurysms. Also, the relation between LAD and development of atrial tachyarrhythmias is discussed.

METHODS

PubMed was searched for studies reporting on atrial aneurysms, left atrial diverticula, left atrial accessory appendages and atrial congenital aneurysms, resulting in 36 papers.

RESULTS

LAD can be distinguished from LAAA by taking into account embryologic origins of the left atrium and their locations, resulting in the following definitions: (a) LAAA are contractile, trabeculated structures with circumscriptive ostia and narrow necks, originating from the primitive atria, (b) LAD are contractile, sac like structures with either smooth or trabeculated inner surfaces, circumscriptive ostia, narrow necks, and variable morphologies, originating from the embryologic common pulmonary vein, that incorporates into the LA, and (c) atrial aneurysms are non-contractile structures with wide necks and sac like bodies. There are no differences in prevalences of LAD between patients with sinus rhythm and AF.

CONCLUSION

The pathophysiology of LAD is not yet fully understood. It is unlikely, that LAD are related to the development of atrial tachycardia's and AF by either being a source of ectopic activity or being part of an arrhythmogenic substrate. No differences in LAD prevalences between patients with sinus rhythm and AF have been found. Thus, it is unlikely that LAD could potentially be wolves in sheep's clothing.

Left Atrial Appendage Mechanical Exclusion: Procedural Planning Using Cardiovascular Computed Tomographic Angiography

Left atrial appendage (LAA) mechanical exclusion is being investigated for nonpharmacologic stroke risk reduction in selected patients with atrial fibrillation. There are multiple potential approaches in various stages of development and clinical application, each of which depends on specific cardiothoracic anatomic characteristics for optimal performance. Multiple imaging modalities can be utilized for application of this technology, with transesophageal echocardiography used for intraprocedural guidance. Cardiovascular computed tomographic angiography can act as a virtual patient avatar, allowing for the assessment of cardiac structures in the context of surrounding cardiac, coronary vascular, thoracic vascular, and visceral and skeletal anatomy, aiding preprocedural decision-making, planning, and follow-up. Although transesophageal echocardiography is used for intraprocedural guidance, computed tomographic angiography may be a useful adjunct for preprocedure assessment of LAA sizing and anatomic obstacles or contraindications to deployment, aiding in the assessment of optimal approaches. Potential approaches to LAA exclusion include endovascular occlusion, epicardial ligation, primary minimally invasive intercostal thoracotomy with thoracoscopic LAA ligation or appendectomy, and minimally invasive or open closure as part of cardiothoracic surgery for other indications. The goals of these procedures are complete isolation or exclusion of the entire appendage without leaving a residual appendage stump or residual flow with avoidance of acute or chronic damage to surrounding cardiovascular structures. The cardiovascular imager plays an important role in the preprocedural and postprocedural assessment of the patient undergoing LAA exclusion.

The characteristics of left atrial diverticula in normal sinüs rhythm patients

PURPOSE

The purpose of this study was to evaluate the prevalence, location, size and morphological characteristics of left atrial diverticula using electrocardiographically gated multi-detector computed tomography in patients with normal sinus rhythm.

METHODS

Electrocardiographically gated cardiac multi-detector computed tomography was performed in 93 patients with normal sinus rhythm. The prevalence, number, size, morphological characteristics and location of left atrial diverticula were recorded.

RESULTS

A total of 72 left atrial diverticula were diagnosed in 45 (48.4%) of the 93 patients in this study. Of these 72 diverticula, 66 (91.7%) were cystiform and 6 (8.3%) were tubiform. Anterosuperior wall, left lateral wall and septum were the most common locations of these left atrial diverticula (n = 42, 58.3%; n = 22, 15.3% and n = 7, 9.7%, respectively).

CONCLUSION

Diverticula are common variations. The discovery of these structures is relatively new and their clinical significance remains unclear. They are generally asymptomatic but although not supported by many studies, in some case reports they are claimed to be associated with arrhythmias and thromboembolism. In addition, it is theoretically reasonable to think that they may cause complications during interventional procedures. Better understanding of these structures has the potential to improve management strategies and reduce potential complications. Therefore, they should be reported during routine cardiac computed tomography.

Multidetector computed tomography in planning the treatment of atrial fibrillation

OBJECTIVE

To know the anatomy of the pulmonary veins (PVs) by multidetector computed tomography (MDCT) in patients with atrial fibrillation (AF) prior to ablation.

MATERIALS AND METHODS

MDCT was performed in 89 patients with AF, analyzing the number of PVs, accessory variants and veins, diameter and ostial shape, distance to the first bifurcation and thrombus in the left atrial appendage.

RESULTS

The most frequent venous pattern was 4 PVs (two right and two. left) in 49 patients (55.1%). The superior veins had a statistically significant greater mean ostial diameter than the inferior veins (Right Superior Pulmonary Vein (RSPV)> Right Inferior Pulmonary Vein (RIPV); p=0.001 and Left Superior Pulmonary Vein (LSPV)> Left Inferior Pulmonary Vein (LIPV); p<0.001). The right pulmonary veins ostial diameters were significantly larger than the left pulmonary veins ostial diameters (RSPV> LSPV; p<0.001 and RIPV> LIPV; p<0.001). The most circular ostium was presented by the VPID (ratio: 0.885) compared to the LIPV (p<00.1) and LSPV (p<0.001). The superior veins had a statistically significant greater mean distance to first bifurcation than the inferior veins (RSPV> RIPV; p=0.008 and LSPV> LIPV; p=0.038). Mean distance to first bifurcation has been greater in left PVs respect to the right PVs (LSPV> RSPV; p<0.001and LIPV> RIPV; p<0.001). Other findings found in AI: diverticula (30), accessory auricular appendages (5), septal aneurysms (8), septal bags (6) and 1 thrombus in the left atrial appendage.

CONCLUSION

MDCT prior to ablation demonstrates the anatomy of the left atrium (LA) and pulmonary veins with significant differences between the diameters and morphology of the venous ostia.

A Sensible Approach to Diagnosing Cardiac Aneurysms, Pseudoaneurysms and Common Mimickers

The heart can manifest a spectrum of focal convexities that range from insignificant crypts and diverticula to clinically relevant aneurysms and pseudoaneurysms. The distinction of a clinically significant lesion from a minor focal convexity can be challenging. This article outlines the various types of focal convexities on the basis of location within the heart and discusses unique morphologic and functional features to further characterize these entities. We also highlight the most critical clinical consequences of cardiac aneurysms and pseudoaneurysms such as thromboembolic events, aneurysm ruptures, intracardiac shunting, hemopericardium, and arrhythmias.

Non-coronary abnormalities of the left heart: CT angiography findings

Cardiac computed tomography (CT) is most commonly performed for the evaluation of the coronary arteries; however, non-coronary cardiac pathologies are frequently detected on these scans. In cases where magnetic resonance imaging cannot be used, cardiac CT can serve as the first-line imaging modality to evaluate many non-coronary cardiac pathologies. In this article, we discuss congenital non-coronary abnormalities of the left heart and their cardiac CT imaging features.

Neonatal repair of left atrial diverticulum with gigantic thrombus without cardiopulmonary bypass

A 5-day-old neonate with coarctation of the aorta, hypoplastic aortic arch, large apical muscular ventricular septal defect, and patent ductus arteriosus developed pulmonary over-circulation and systemic hypoperfusion underwent bilateral pulmonary artery banding through median sternotomy as a part of hybrid stage I palliation. At operation, left atrial diverticulum with gigantic thrombus formation at the base of the left atrial appendage was incidentally detected by intraoperative direct echocardiography, and therefore, was successfully resected with the whole thrombus inside it without use of cardiopulmonary bypass. Histopathological finding was compatible with diverticulum. The patient was free from atrial arrhythmia and recurrent thrombus formation.

Prevalence of left atrial abnormalities in atrial fibrillation versus normal sinus patients

Background

Atrial fibrillation (AF) may be the cause or sequela of left atrial abnormalities and variants.

Purpose

To determine the prevalence of left atrial (LA) abnormalities in AF patients compared to normal sinus rhythm (NSR) patients.

Material and Methods

We retrospectively reviewed 281 cardiac CT examinations from 2010 to 2012, excluding patients with prior pulmonary vein ablation, known coronary artery disease, prior coronary stent placement, or coronary artery bypass grafts. The first group consisted of 159 AF patients undergoing cardiac CT prior to pulmonary vein ablation and the second group consisted of 122 NSR patients evaluated with coronary CT angiography. Demographic data were collected. LA abnormalities were analyzed. Left atrial diameter was measured on an axial view.

Results

A total of 281 patients were included. The male gender has significantly higher prevalence of AF than female gender, P value <0.001. Patients with AF were significantly older (mean age, 57.4 years; standard deviation [SD], 11.8 years) than NSR patients (mean age, 53.4 years; SD, 13.6 years), P value, 0.01. The left atrial diameter was greater in the AF patients (mean diameter, 4.3 cm; SD, 0.82 cm) versus the NSR patients (3.4 cm; SD, 0.58 cm), P value, <0.0001. LA diverticulum was the most prevalent variant, occurring in 28.4% of the entire patient population followed by LA pouch, occurring in 24%. There was no significant between group differences in the prevalence of these or the remainder of the LA variants.

Conclusion

AF patients differed significantly from NSR patients in LA size, gender, and mean age. There was no statistical significance between the two groups with regard to the LA morphologic abnormalities other than size.

Assessments of pulmonary vein and left atrial anatomical variants in atrial fibrillation patients for catheter ablation with cardiac CT

OBJECTIVES

To provide a road map of pulmonary vein (PV) and left atrial (LA) variants in patients with atrial fibrillation (AF) before catheter ablation procedure using cardiac CT.

METHODS

Cardiac CT was performed in 1420 subjects for accurate anatomical information, including 710 patients with AF and 710 matched controls without AF. PV variants, PV ostia and spatial orientation, LA enlargement, and left atrial diverticulum (LAD) were measured, respectively. Differences between these two groups were also respectively compared. Some risk factors for the occurrence of LAD were analyzed.

RESULTS

In total, PV variants were observed in 202 (28.5 %) patients with AF patients and 206 (29.0 %) controls without AF (p = 0.8153). The ostial sizes of all accessory veins were generally smaller than those of the typical four PVs (p = 0.0153 to 0.3958). There was a significant difference of LA enlargement between the AF and control groups (36.3 % vs. 12.5 %, p < 0.0001), while the prevalence of LAD was similar in these two groups (43.2 % vs. 41.9 %, p = 0.6293).

CONCLUSION

PV variants are common. Detailed knowledge of PVs and LA variants are helpful for providing anatomical road map to determine ablation strategy.

KEY POINTS

• PVs variants are helpful for providing anatomical road map to ablation. • PV variants are common. • DSCT could recognize these anatomic features before ablation as a non-invasive imaging.

Anatomical features and clinical importance of left atrial diverticula: MDCT findings

To assess the anatomical features and clinical importance of left atrial diverticula and atrial accessory appendages in patients undergoing cardiac computed tomography with multidetector computed tomography. A total of 1305 consecutive patients (385 female, 29.5%; 920 male, 70.5%) were assessed using electrocardiogram-gated computed tomography between May 2010 and June 2013. The anatomical features and the prevalences of left atrial diverticula and left atrial accessory appendages were retrospectively assessed by four radiologists. The relationships between the prevalence and size of the diverticula and the age and gender of the patients were assessed. Among the 1305 patients, 610 (46.7%) exhibited 708 left atrial diverticula, and 62 (4.8%) exhibited left atrial accessory appendages. The most common locations of the left atrial diverticula were the right anterior superior wall (n = 328, 46.3%) and the lateral superior wall (n = 96, 13.5%). In addition to classical cystic and tubular diverticula, 49 (3.7%) of the patients exhibited mixed (cystic-tubular), conical, or hook-shaped diverticula and diverticular forms containing mural calcifications. There was no significant relationship between the prevalence of diverticula and the age and gender of the patients (P > 0.05). In addition to tubular and cystic diverticula, the left atrial wall can host different diverticular forms (such as mixed, conical, calcific, and hook shaped). It could be beneficial to assess the left atrium using MDCT to determine the source of emboli in cryptogenic embolism and to reduce complications associated with interventional procedures performed for left atrial arrhythmias.

Lack of association between stroke and left atrial out-pouching structures: results of a case-control study

Background and Purpose

Clinical significance of out-pouching structures of the left atrium (LA) as potential embolic sources remains unclear. We sought to evaluate the association between stroke and LA out-pouching structures.

Methods

A case-control study was conducted to assess the prevalence of LA out-pouching structures in subjects with and without stroke. Case subjects were 270 stroke patients who had undergone cardiac CT. Control subjects were 270 age- and sex-matched patients without a history of stroke and who had undergone cardiac CT. Presence of LA out-pouching structures was determined by ECG-gated cardiac CT. The location of out-pouching structures was categorized as near Bachmann bundle, anterior, inferoseptal, inferior, and lateral. The prevalence, number and location of out-pouching structures and clinical characteristics were compared between the two groups.

Results

One hundred sixty eight out-pouching structures were identified in 139 stroke patients (51%), while a total of 169 out-pouching structures were found in 155 control patients (57%) (p=0.1949). The prevalence of LA out-pouching structures with different locations was not significantly different between the stroke group and control group. In the stroke group, the prevalence of out-pouching structures was not significantly different by subtypes of ischemic stroke and the prevalence of LA out-pouching structures was not different between patients with atrial fibrillation (AF) and without AF.

Conclusion

The left atrial out-pouching structures are commonly seen in a population with and without stroke with similar prevalence. Our study suggests that LA out-pouching structures are not significant risk factors of stroke.

Transcatheter left atrial appendage occlusion

Occlusion of the left atrial appendage (LAA) may reduce the risk of stroke in patients with atrial fibrillation (AF). Trials comparing LAA occlusion to warfarin anticoagulation in patients with nonvalvular AF showed a reduction in hemorrhagic stroke, although an increase in safety events due to procedural complications. Long-term follow-up suggests possible superiority of LAA occlusion due to fewer strokes and bleeding events. The superior dosing and safety profiles of the novel oral anticoagulants raise the accepted threshold for safety and efficacy of LAA occlusion procedures, and underscore the need for randomized studies comparing LAA occlusion with these newer anticoagulants.

Role of cardiac computed tomography and cardiovascular magnetic resonance imaging in guiding management and treatment of patients with atrial fibrillation: state of the art review

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and is associated with high morbidity and mortality. In view of an aging population, the prevalence and incidence of AF are on the rise and are expected to double in the coming decades, posing a huge economic burden on already strained resources. New innovative therapies such as pulmonary vein isolation and percutaneous closure of the left atrial appendage have emerged. The current applications of such therapies would not have been possible without the pivotal role of multimodality cardiovascular imaging. The role of echocardiography in guiding therapy has been extensively reviewed. However, there are new data in support of other complementary imaging modalities, mainly cardiac computed tomography and cardiovascular magnetic resonance imaging, which will be the focus of this review.

Left Atrial Diverticula in Patients Referred for Radiofrequency Ablation of Atrial Fibrillation

Background—

The anatomic features of left atrial diverticula (LAD) are still unclear in patients with atrial fibrillation (AF). The purpose of this study was to evaluate the prevalence and morphological characteristics of LAD in patients referred for radiofrequency transcatheter ablation of AF with dual-source computed tomography.

Methods and Results—

Dual-source computed tomography images were obtained in 214 patients referred for AF catheter ablation and 214 sex- and age-matched control subjects. Images were analyzed to determine the prevalence and morphological characteristics of LAD and their relationship with adjacent pulmonary veins and left atrial appendage. In AF patients 77 (36.0%) (95% confidence interval, 29.6–42.4%) had 90 LAD, whereas in control subjects 70 (32.7%) (95% confidence interval, 26.4–39.0%) had 81 LAD ( P =0.551). In patients with AF, LAD locations were right anterosuperior (47.8%), left anterosuperior (8.9%), left lateral (32.2%), interatrial septum (4.4%), right inferior (5.6%), and posterosuperior (1.1%) walls, respectively. The mean size of LAD was 5.3±2.9×5.6±3.3 mm. The wall of the LAD was much thinner than that of adjacent left atrium (0.89±0.46 versus 2.39±0.83 mm). Most LAD were located close to a pulmonary vein or atrial appendage ostium, with a mean distance of 8.7–13.1 mm.

Conclusions—

LAD are common, with a prevalence of 36.0% in patients with AF, which is not statistically greater than that in patients without AF. Thin-walled LAD are more commonly located on the superior anterior wall of left atrium and close to common ablation sites.

Multidetector CT of left atrium

MDCT angiography has enabled visualization of left atrium in addition to coronary arteries. CT images can be utilized to demonstrate normal anatomy and pathologies. Left atrium variations and pathologies include atrial septal pouch, patent foramen ovale, atrial septal defect, atrial band, lipomatous hypertrophy, cor triatriatum, diverticulum, accessory appendages, atrial thrombus and masses. Left atrium should be carefully evaluated in patients undergoing coronary CT angiography. MDCT is becoming an alternative modality for the evaluation of left atrium.

Accessory left atrial diverticulae: contractile properties depicted with 64-slice cine-cardiac CT

To assess the contractility of accessory left atrial appendages (LAAs) using multiphasic cardiac CT. We retrospectively analyzed the presence, location, size and contractile properties of accessory LAAs using multiphasic cardiac 64-slice CT in 102 consecutive patients (63 males, 39 females, mean age 57). Multiplanar reformats were used to create image planes in axial oblique, sagittal oblique and coronal oblique planes. For all appendages with an orifice diameter >or= 10 mm, axial and sagittal diameters and appendage volumes were recorded in atrial diastole and systole. Regression analysis was performed to assess which imaging appearances best predicted accessory appendage contractility. Twenty-three (23%) patients demonstrated an accessory LAA, all identified along the anterior LA wall. Dimensions for axial oblique (AOD) and sagittal oblique (SOD) diameters and sagittal oblique length (SOL) were 6.3-19, 3.4-20 and 5-21 mm, respectively. All appendages (>or=10 mm) demonstrated significant contraction during atrial systole (greatest diameter reduction was AOD [3.8 mm, 27%]). Significant correlations were noted between AOD-contraction and AOD (R = 0.57, P < 0.05) and SOD-contraction and AOD, SOD and SOL (R = 0.6, P < 0.05). Mean diverticulum volume in atrial diastole was 468.4 +/- 493 mm(3) and in systole was 171.2 +/- 122 mm(3), indicating a mean change in volume of 297.2 +/- 390 mm(3), P < 0.0001. Stepwise multiple regression analysis revealed SOL to be the strongest independent predictor of appendage contractility (R(2) = 0.86, P < 0.0001) followed by SOD (R(2) = 0.91, P < 0.0001). Accessory LAAs show significant contractile properties on cardiac CT. Those accessory LAAs with a large sagittal height or depth should be evaluated for contractile properties, and if present should be examined for ectopic activity during electrophysiological studies.