Morphological features of the left atrial appendage in consecutive coronary computed tomography angiography patients with and without atrial fibrillation

Gross anatomic relationship between the human left atrial appendage and the left ventricular summit region: implications for catheter ablation of ventricular arrhythmias originating from the left ventricular summit

PURPOSE

The left ventricular summit (LVS) is a source of difficult-to-treat arrhythmias because of anatomical limitations. The aim of this study was to perform detailed research of the left atrial appendage (LAA) anatomy of cadaveric hearts to analyze their complex anatomy and coverage of the LVS.

METHODS AND RESULTS

Eighty human formalin fixed hearts (mean age 44.4 ± 15.5, 27.5% females) were investigated. Each LAA size, type, and its relationship to the LVS were analyzed, as well as possible access sites for mapping/ablating electrode. Four types of LAA were observed over two LVS sites that are either accessible or not. The highest coverage over an inaccessible LVS area was observed in the Broccoli type, followed by the Windsock then the Chicken Wing and finally the Cactus types; over the accessible area of the LVS was observed in the Windsock, then in the Chicken Wing, then in the Cactus, and finally in the Broccoli types. The attainable coverage for electrode access is diminished from 25 to 65% because of the complex pectinate muscles and sharp angles. The highest density of the LAA floor made by pectinate muscles can be found in the Broccoli type (p < 0.005), while the Chicken Wing had the highest number of paper-thin-like pouches.

CONCLUSIONS

The LAA appears to be a promising entry for ablation-qualified patients with the LV summit originate arrhythmias. The complex internal structure of the LAA may complicate ablation procedures. More prominent appendages are promising in more extensive mapping areas over the LVS.

Morphological changes in the orifices of the left atrial appendage and left atrium in patients with atrial fibrillation

BACKGROUND

As an integral part of the left atrium (LA), the left atrial appendage (LAA) plays an important role in atrial fibrillation (AF). However, the relationship between LAA remodeling and AF has not been clearly defined. This retrospective case-control study aimed to assess the morphological and functional features of the LA and the LAA in AF patients using images obtained by computed tomography angiography (CTA).

METHODS

A total of 140 AF patients and 64 patients without AF or other cardiovascular diseases who underwent CTA scans between September 2016 and August 2017 were enrolled in this observational study as the experimental and the control groups, respectively. The major and minor axes, area, and perimeter of the LAA orifice, the LAA depth, and the volume of both the LAA and LA were analyzed. The data of the AF group and the control group were compared. The t-test was used to analyze the normally distributed data, and the Wilcoxon rank-sum test was used for abnormally distributed data. The best critical value of predictors of AF was calculated using receiver operating characteristic (ROC) curve analysis. The correlation of the LAA volume change with the major and minor axes, area, and perimeter of the LAA orifice, and the LAA depth were analyzed using the Pearson correlation coefficient.

RESULTS

The LAA orifice's minor axis, LAA volume, and LA volume were significantly greater (P=0.004, P=0.010, and P<0.001, respectively) in patients with AF than in those without AF. The LAA volume [95% confidence interval (CI): 1.01 to 1.30; P=0.038] and LA volume (95% CI: 1.03 to 1.07; P<0.001) were significantly independent predictors of AF. An LAA volume of 8.75 mL had the highest predictive value for AF [area under the curve (AUC), 0.612], with a sensitivity of 76.6% and a specificity of 48.6%. In contrast, an LA volume of 97.15 mL had the highest predictive value for AF (AUC, 0.771), with a sensitivity of 90.6% and a specificity of 53.6%. The change of LAA volume was positively weakly correlated with the area and perimeter of the LAA orifice (r=0.1703 and r=0.1378, respectively). The LAA emptying fraction was negatively correlated with the major axis and the area of the LAA orifice. The major and minor axes, area, and perimeter of the LAA orifice, and LAA depth were significantly greater in female than in male patients (P=0.003, P=0.003, P=0.001, P=0.019, and P<0.001, respectively).

CONCLUSIONS

The AF patients had a longer minor axis of the LAA orifice than that of the control group, resulting in a more circular LAA orifice. The LAA orifice area and perimeter were positively correlated with LAA volume change. The LAA orifice major and minor axes, area, and perimeter, and the LAA depth of the female patients were significantly greater than those of their male counterparts in AF patients.

Computational fluid dynamics of blood flow in an idealized left human heart

We construct an idealized computational model of the left human heart for the study of the blood flow dynamics in the left atrium and ventricle. We solve the Navier-Stokes equations in the ALE formulation and we prescribe the left heart wall displacement based on physiological data; moreover, we consider the presence of both the mitral and aortic valves through the resistive method. We simulate the left heart hemodynamics by means of the finite element method and we consider the variational multiscale large eddy simulation (LES) formulation to account for the transitional and nearly turbulent regimes of the blood flow in physiological conditions. The main contribution of this paper is the characterization of the blood flow in an idealized configuration of the left heart aiming at reproducing function in normal conditions. Our assessment is based on the analysis of instantaneous and phase averaged velocity fields, blood pressure, and other clinically meaningful fluid dynamics indicators. Finally, we show that our idealized computational model can be suitably used to study and critically discuss pathological scenarios like that of a regurgitant mitral valve.

Interventional occlusion of left atrial appendage in patients with atrial fibrillation. Gender-related outcomes in the German LAARGE Registry

INTRODUCTION

Gender-based differences in atrial fibrillation have been identified, but limited data exist for patients undergoing left atrial appendage occluder (LAAO) implantation. This study reports gender-related periprocedural and 1-year outcomes of the prospective, multicenter German left atrial appendage occlusion registry (LAARGE).

METHODS

LAARGE enrolled 641 patients who were scheduled for LAAO implantation from July 2014 to January 2016 in 38 hospitals in Germany. The data collected included demographics, clinical characteristics, details of implantation, and outcome. Efficacy and safety at 1-year follow-up were assessed by the occurrence of thrombembolic and bleeding events, as well as mortality.

RESULTS

Of 638 patients undergoing LAAO implantation 38.9% were female and 61.1% male. Females were older (76.4 ± 8.2 [females] vs. 75.6 ± 7.7 [males], p = .042) and had a higher stroke risk (CHA₂ DS₂ -VASc score: 4.9 ± 1.5 vs. 4.3 ± 1.5, p < .001). In contrast, males suffered more often from coronary artery (33.1% vs. 53.8%, p < .001) and vascular disease (18.5% vs. 31.0%, p < .001). Technical success was high and similar for both genders (98.4% vs. 97.2%, p = .33). Severe periprocedural complications (6.9% vs. 3.1%, p = .032) occurred more often in females. At 1-year follow-up the rates of all-cause stroke (0.5% vs. 1.3%, p = .65) and severe bleeding (0.0% and 1.0%, p = .29) were low and comparable between the genders. Also, one-year all-cause mortality (9.2% vs. 13.1%, p = .14) did not differ significantly.

CONCLUSION

LAARGE documented in this elderly patient population undergoing LAAO implantation a higher rate of severe periprocedural complications in females. At 1-year follow-up similar efficacy and safety outcomes were observed for both genders.

The left atrial appendage morphology and gender differences by multi-detector computed tomography in an Egyptian population

Background

The left atrial appendage (LAA) is the main source of thromboembolism in patients with non-valvular atrial fibrillation. Unique LAA morphologies have been associated with the risk of thromboembolism. This study investigates the LAA anatomy in the Egyptian population using cardiac multi-detector computed tomography (MDCT).

Results

We included 252 consecutive patients presenting for coronary computed tomography angiography in 2 tertiary centers in Egypt in the period from January to July 2017. Patients with atrial fibrillation, valvular affection, or left ventricular dysfunction were excluded. Two and three-dimensional cardiac MDCT images were assessed for LAA morphology, volume, length, and orifice position. The distribution of LAA morphologies was windsock (32.5%), chicken wing (25.4%), cauliflower (22.6%), and cactus (19.4%). Differences in the LAA dimensions in the 4 morphological variants were described. Females were less likely to have a chicken wing LAA morphology compared to males (7.9% vs 34.7%, p value < 0.01), and had a larger LAA volume, smaller LAA length, and a higher prevalence of high LAA orifice position.

Conclusions

The most common LAA morphology in our study population is windsock, which may represent the Egyptian population or patients in sinus rhythm. Females were less likely to have a chicken wing LAA morphology, and had a larger LAA volume, smaller length, and higher incidence of high orifice position. Clinical correlation into the translation of these differences into thromboembolic risk is required.

Difference in left atrial appendage remodeling between diabetic and nondiabetic patients with atrial fibrillation

Background

Diabetes mellitus (DM) is a common and increasingly prevalent condition in patients with atrial fibrillation (AFib). The left atrium appendage (LAA), a small outpouch from the LA, is the most common location for thrombus formation in patients with AFib.

Hypothesis

In this study, we examined LAA remodeling differences between diabetic and nondiabetic patients with AFib.

Methods

This retrospective study analyzed data from 242 subjects subdivided into two subgroups of 122 with DM (diabetic group) and 120 without DM (nondiabetic group). The study group underwent real‐time 3‐dimensional transesophageal echocardiography (RT3DTEE) for AFib ablation, cardioversion, or LAA device closure. The LAA dimensions were measured using the “Yosefy rotational 3DTEE method.”

Results

The RT3DTEE analysis revealed that diabetic patients display larger LAA diameters, D1‐lengh (2.09 ± 0.50 vs 1.88 ± 0.54 cm, P = .003), D2‐width (1.70 ± 0.48 vs 1.55 ± 0.55 cm, P = .024), D3‐depth (2.21 ± 0.75 vs 1.99 ± 0.65 cm, P = .017), larger orifice areas (2.8 ± 1.35 and 2.3 ± 1.49 cm², P = .004), and diminished orifice flow velocity (37.3 ± 17.6 and 43.7 ± 19.5 cm/sec, P = .008).

Conclusions

Adverse LAA remodeling in DM patients with AFib is characterized by significantly LAA orifice enlargement and reduced orifice flow velocity. Analysis of LAA geometry and hemodynamics may have clinical implications in thrombotic risk assessment and treatment of DM patients with AFib.

Diagnosis of coronary artery disease in patients with atrial fibrillation using low tube voltage coronary CT angiography with isotonic low-concentration contrast agent

This prospective study evaluated the image quality and accuracy of coronary computed tomography angiography (CCTA) for diagnosing coronary artery disease (CAD) in patients with atrial fibrillation (AF), in which CCTA used adaptive iterative dose reduction (AIDR) with a low tube voltage and low concentration of isotonic contrast agent. Sixty-eight consecutive patients with AF and suspected CAD were equally and randomly apportioned to two groups and underwent CCTA. In the experimental group, the contrast agent was iodixanol (270 mg I/mL), patients were scanned with 100 kV, and reconstruction was by AIDR. In the conventional scanning (control) group, the contrast agent was iopromide (370 mg I/mL), patients were scanned with 120 kV, and reconstruction was by filtered back projection. The image quality, effective radiation dose (E), and total iodine intake of the groups were compared. Thirty-nine patients with coronary artery stenosis later were given invasive coronary angiography (ICA). The groups were similar with regard to mean CT value, noise, and signal-to-noise and contrast-to-noise ratios. The figure of merit of the experimental group was significantly higher than that of the control group, while the E and total iodine were significantly lower. Using ICA as the diagnostic reference, the groups shared similar sensitivity, specificity, and false positive and false negative rates for diagnosing coronary artery stenosis. For determining CAD in patients with AF, CCTA with isotonic low-concentration contrast agent and low-voltage scanning is a feasible alternative that improves accuracy and reduces radiation dose and iodine intake.

Complex Left Atrial Appendage Morphology Is an Independent Risk Factor for Cryptogenic Ischemic Stroke

Importance: Ischemic strokes pose a significant health burden. However, the etiology of between 20 and 40% of these events remains unknown. Left atrial appendage morphology may influence the occurrence of thromboembolic events. Design: A retrospective cross-sectional study was conducted to investigate the role of LAA morphology in patients with atrial fibrillation (AF) and cardioembolic-associated stroke and patients with cryptogenic stroke without atrial fibrillation. LAA morphology is classified into two groups: (1) simple (chicken-wing) vs. (2) complex (non-chicken wing) based on transesophageal echocardiography (TEE) findings. In addition to the LAA morphology, left atrial parameters, including orifice diameter, depth, emptying velocity, and filling velocity, were collected for both groups. Mathematical, computational models were constructed to investigate flow velocities in chicken-wing and non-chicken wing morphological patterns to assess LAA function further. Findings: TEE values for volume, size, emptying, and filling velocities were similar between simple and complex LAA morphology groups. Patients with cryptogenic stroke without coexisting AF were noted to have significantly higher rates of complex LAA morphology. Chicken-wing LAA morphology was associated with four-fold higher flow rate (kg/s) in computational simulations. Conclusions: Complex LAA morphology may be an independent contributing factor for cryptogenic strokes. Further studies are warranted to investigate the mechanism involved in LAA morphology and thromboembolic events.

Left atrial appendage morphology and relative contrast agent concentration in patients undergoing coronary artery CTA

AIM

To evaluate whether certain morphological features of the left atrial appendage (LAA) would influence the LAA/ascending aorta (AA) radiodensity ratio, as a reflection of the blood flow conditions in the LAA.

MATERIALS AND METHODS

Eight-hundred and eight consecutive patients undergoing computed tomography angiography (CCTA) were evaluated. Of these, 749 had no history of atrial fibrillation and none had suffered acute stroke. The LAA/AA radiodensity ratio, and the length, lobe number, and morphological classification of LAAs were assessed.

RESULTS

The distribution of morphological classes for LAAs were: windsock 62.3%, cactus 18.6%, chicken wing 10.0%, and cauliflower 9.2%. The mean LAA/AA radiodensity ratio was 0.87±0.14 (range 0.22-1.44). Female gender (p=0.001), elevated body mass index (BMI; r=-0.129; p=0.003), and diabetes (p=0.03) were associated with lower LAA/AA radiodensity ratios, while heart failure (p=0.017), significant coronary artery stenosis (p=0.010), and LAAs with multiple lobes (p=0.018), exhibited higher LAA/AA radiodensity ratios. Multiple regression analysis revealed that a short one-lobed cauliflower morphology was an independent predictor (p=0.007) of a decreased LAA/AA radiodensity ratio.

CONCLUSION

A decline in the LAA/AA radiodensity ratio may reflect decreased blood flow in the LAA, paralleling spontaneous echo contrast in transoesophageal echocardiography. Thus, CCTA might be of value in recognising LAA structures that predispose to decreased blood flow.