Benefit of Four-Dimensional Computed Tomography Derived Ejection Fraction of the Left Atrial Appendage to Predict Thromboembolic Risk in the Patients with Valvular Heart Disease

Morphological and functional assessment of the left atrial appendage in daily practice: a comprehensive approach using basic and advanced echocardiography with practical tips

Cardioembolic stroke is the most serious and life-threatening complication of atrial fibrillation (AF), with an associated mortality up to 30% at 12 months. Approximately 47% of thrombi in valvular AF and 91% of thrombi in nonvalvular AF are localized in the left atrial appendage (LAA). Therefore, identification or exclusion of LAA thrombi is critical in many clinical situations. It is essential to assess LAA morphology and function using imaging modalities (particularly echocardiography) before, during, and after interventional procedures such as AF ablation and LAA occlusion. This review article describes the anatomical, physiological, and pathological background of the LAA, followed by an assessment of different echocardiographic modalities. Many practical points are included to improve the diagnostic accuracy and to minimize errors during image acquisition and interpretation. In each clinical scenario where LAA is the crucial target, specific and essential information and parameters are collected.

Multidimensional Approach of Heart Failure Diagnosis and Prognostication Utilizing Cardiac Imaging with Biomarkers

Heart failure (HF) is a clinical syndrome caused by various etiologies that results in systolic and diastolic cardiac dysfunction with congestion. While evaluating HF and planning for treatment, physicians utilize various laboratory tests, including electrocardiography, diverse imaging tests, exercise testing, invasive hemodynamic evaluation, or endomyocardial biopsy. Among these, cardiac imaging modalities and biomarkers are the mainstays during HF diagnosis and treatment. Recent developments in non-invasive imaging modalities, such as echocardiography, computed tomography, magnetic resonance imaging, and nuclear imaging, have helped us understand the etiology, pathophysiology, and hemodynamics of HF, and determine treatment options and predict the outcomes. Due to the convenience of their use and potential impact on HF management, biomarkers are increasingly adopted in our clinical practice as well as research purpose. Natriuretic peptide is the most widely used biomarker for the diagnosis of HF, evaluation of treatment response, and prediction of future outcomes. Other cardiac biomarkers to evaluate the pathophysiological mechanisms of HF include myocardial injury, oxidative stress, inflammation, fibrosis, hypertrophy, and neurohormonal activation. Because HF results from complex cardiac disorders, it is essential to assess the disease status multidimensionally. The proper utilization of multimodality imaging and cardiac biomarkers can improve the quality of patient management and predict clinical outcomes in HF in the era of personalized medicine.

Transesophageal Echocardiography Following Left Atrial Appendage Electrical Isolation: Diagnostic Pitfalls and Clinical Implications

BACKGROUND

Following left atrial appendage (LAA) electrical isolation, the decision on whether to continue oral anticoagulation after successful atrial fibrillation ablation is based on the study of its mechanical function on transesophageal echocardiography (TEE). In this cohort, LAA contraction is absent and the incorrect interpretation of emptying flow velocities can lead to unwanted clinical sequelae.

METHODS

One hundred and sixty consecutive TEE exams performed to evaluate the LAA mechanical function following its electrical isolation were reviewed by an experienced operator blinded to the original diagnosis of LAA dysfunction. The rate of diagnostic discrepancy in the assessment LAA dysfunction and its clinical implications were evaluated.

RESULTS

Diagnostic discrepancy with misclassification of the LAA mechanical function occurred 36% (58/160) of TEE exams. In most cases (57/58), such discrepancy was observed in the setting of an incorrect original diagnosis of a normal LAA mechanical function despite absent/reduced or inconsistent LAA contraction. This main source of this wrong diagnosis was the wrong interpretation of passive LAA flows (34/57; 60%), followed by failure to identify dissociated firing (15/57; 26%). In rare cases (8/57; 14%), velocities of surrounding structures were interpreted as LAA flow due to misplacement of the pulsed-wave Doppler sample volume. Following LAA isolation, the proportion of patients who experienced a cerebrovascular event while off oral anticoagulation due to the misclassification of their LAA mechanical function was 70% (7/10 [95% CI, 40%-89%]).

CONCLUSIONS

Underdiagnosis of LAA mechanical dysfunction is common in TEEs performed following LAA electrical isolation, and it is associated with an increased risk of cerebrovascular events owing to oral anticoagulation discontinuation despite absent/reduced LAA contraction. Careful review of the TEE exam by an operator with specific expertise in LAA imaging and familiar with the functional implications of LAA isolation is necessary before interrupting oral anticoagulation in this cohort.

Computed Tomography of the Left Atrium and Left Atrial Appendage: A Pictorial Essay on the Anatomy, Normal Variants, and Pathology

전산화단층촬영(이하 CT) 영상 기술의 발전으로 박동하는 심장에 대한 섬세한 영상의학적 평가가 가능해졌다. 심초음파 및 MRI에 비해 심장 CT의 강점은 대부분의 의료기관에 보급되어 있고 고품질 이미지의 빠른 생산이 가능하며 해부학적 묘사가 뛰어나다는 것이다. 좌심방과 좌심방이에서 생기는 대부분의 변이 혹은 병리적 상태들은 CT 상의 소견만으로도 추정진단을 내릴 수 있다. 또한 CT 영상은 성공적인 카테터 기반 시술 또는 수술에 중요한 해부학적 정보들을 제공한다. 특히 좌심방과 좌심방이는 심방세동 환자들의 치료 및 관리에 중요한데, 이는 다양한 카테터 기반 시술들이 두 구조물의 기계적 혹은 전기적 차단을 목표로 하기 때문이다. 따라서 임상적으로 의미 있는 판독을 위해서는 병리적 상태의 CT 소견 기술과 함께 좌심방 및 좌심방이의 모양, 크기 및 주변 구조물과의 상대적 위치 관계 등에 대한 포괄적인 검토를 해야 한다.

Simultaneous Functional and Morphological Assessment of Left Atrial Appendage by 3D Virtual Models

Purpose

The left atrial appendage (LAA) is responsible for thrombus formation in patients with atrial fibrillation. The evaluation of both LAA function and morphology is crucial for the patient characterization and the preprocedural planning of LAA closure intervention. Despite the availability of 3D imaging modalities, the current standard image analysis is based on manual delineation of the LAA contours on 2D views.

Methods

In this study, a comprehensive approach based on a full 3D analysis of the tomographic dataset by surface extraction and processing (3D-S) is presented. The proposed method allows extracting functional and morphologic information in the entire cardiac cycle by minimalizing manual user interaction. The proposed methodology has been validated on ten computer tomography datasets.

Results

The proposed 3D-S method was feasible in all cases. Reproducibility was improved with respect to the reference 2D manual procedure (2D-S) (coefficient of variation 2.9 vs. 4.1% for diastolic ostium area; 3.8 vs. 6.1% for systolic ostium area; 2.4 vs. 5.3% for diastolic LAA volume; 2.7 vs. 5.9% for systolic LAA volume; and 7.7 vs. 17.1% for LAA ejection fraction). No significant differences were found between 2D-S and 3D-S measurements.

Conclusions

In this study, we introduced a fully 3D approach for LAA characterization, allowing the simultaneous assessment of LAA function and geometry. The proposed approach could be used to improve the patient selection and the best sizing of the device for LAA closure and to allow a patient-specific 3D printing.