Atrial fibrillation (AF) is the prevalent persistent cardiac arrhythmia seen in clinical settings and is a significant public health issue globally. The incidence of AF is rising due to older populations, better survival rates from cardiovascular diseases, and the escalating impact of risk factors like hypertension, diabetes mellitus, obesity, and heart failure. AF is linked to significant morbidity and mortality, mainly due to its close connection with thromboembolic incidents, especially ischemic stroke. Individuals with AF face about a five-fold heightened risk of stroke compared to those in normal sinus rhythm, and strokes associated with AF tend to be more severe, leading to increased disability and mortality. Consequently, recognizing elements that influence thromboembolic risk in AF is a vital part of cardiovascular research and clinical care.

The mechanism of thrombus formation in AF is complex and is often described by Virchow’s triad, comprising blood stasis, endothelial impairment, and increased coagulability. In AF, the lack of synchronized atrial contraction results in reduced blood flow in the left atrium, especially in the left atrial appendage (LAA). The LAA is a muscular, finger-like projection that stems from the left atrium and is recognized as the main location for thrombus development in non-valvular AF. Research has shown that around 90% of thrombi in individuals with non-valvular AF arise from the LAA, underscoring its significant contribution to thromboembolic issues.

Historically, assessing thromboembolic risk in AF has depended on clinical scoring systems like the CHA₂DS₂-VASc score. Although these tools have demonstrated their worth in directing anticoagulation therapy, they fail to completely consider the differences in stroke risk seen among patients with comparable clinical characteristics. As a result, more focus has been placed on anatomical and structural elements that could affect thrombogenesis. Among these factors, the shape of the LAA has become a potentially significant determinant of thromboembolic risk.

Improvements in cardiovascular imaging methods, such as transesophageal echocardiography (TEE), multidetector computed tomography (MDCT), and cardiac magnetic resonance imaging (CMR), have allowed for comprehensive depiction of LAA structure. These imaging techniques have shown considerable differences between individuals in LAA size, shape, volume, orientation, and the number of lobes. Using imaging observations, scientists have divided LAA morphology into several unique types, particularly the “chicken wing,” “cactus,” “windsock,” and “cauliflower” types. Every morphological type displays distinct structural characteristics that can affect blood flow dynamics and thrombus development.

The morphology of chicken wings features a notable curve in the primary lobe and is regarded as the most prevalent LAA configuration. Multiple studies indicate that patients with chicken wing morphology have a reduced risk of thromboembolic events compared to those with different morphologies. The acute curve found in this arrangement may enhance the efficient drainage of blood from the appendage, thus lowering stasis and the risk of thrombus formation. In contrast, morphologies that are not chicken wing, like cauliflower and cactus formations, are typically linked to more intricate anatomy, several lobes, and uneven internal trabeculations, elements that might lead to reduced blood flow and heightened thrombogenic potential.

Hemodynamic investigations have additionally reinforced the connection between LAA structure and the risk of thromboembolism. Analyses in computational fluid dynamics have shown that specific morphological shapes create regions of low blood flow velocity, extended blood residence duration, and heightened turbulence in the appendage. These factors encourage blood stagnation and aid in the development of clots. Moreover, increased LAA volumes, a higher count of lobes, and diminished LAA emptying velocities have been linked to spontaneous echo contrast and thrombus development, highlighting the significance of structural features in evaluating stroke risk.

Even with increasing evidence, the clinical importance of LAA morphology is still under active research. Certain research has indicated strong links between particular LAA morphologies and the incidence of stroke, while other studies have revealed only weak or variable connections after controlling for standard clinical risk factors. Differences in imaging protocols, classification techniques, sample sizes, and patient demographics might partially account for these inconsistencies. Moreover, the subjective aspect of morphological classification has sparked worries about interobserver variability and reproducibility.

Recent studies have progressed beyond basic morphological classification to incorporate quantitative evaluation of LAA parameters. Metrics like LAA orifice diameter, appendage depth, volume, trabecular complexity, and flow velocity have shown potential significance in forecasting thromboembolic risk. Merging

With the shift toward precision-based methods in cardiovascular medicine, combining anatomical biomarkers with clinical and laboratory information could improve personalized patient treatment. LAA structure serves as a potential imaging biomarker that may enhance existing thromboembolic risk evaluation models. Nevertheless, further extensive prospective research is essential to create standardized classification systems, elucidate the individual predictive significance of different morphological attributes, and ascertain how these outcomes can be integrated into regular clinical practice.

Considering the significant impact of AF-related strokes and the shortcomings of current risk assessment techniques, examining the link between LAA structure and thromboembolic risk holds substantial clinical significance. Enhanced comprehension of this link could lead to better identification of at-risk patients, refinement of preventive measures, and ultimately a decrease in stroke-related morbidity and mortality in those with atrial fibrillation.

This analytical cross-sectional study took place in the Department of Cardiology at Mayo Hospital Lahore, spanning from January 2025 to January 2026, to assess the relationship between left atrial appendage (LAA) shape and thromboembolic risk in non-valvular atrial fibrillation (AF) patients. Two hundred patients with confirmed non-valvular AF were enrolled via consecutive non-probability sampling. Individuals 18 years and older who had transesophageal echocardiography (TEE) or cardiac computed tomography angiography (CCTA) to assess the left atrial appendage were part of the study. Individuals with atrial fibrillation related to valvular issues, congenital heart defects, prior left atrial appendage closure procedures, cardiac tumors, poor imaging quality, or insufficient clinical documentation were not included. Informed consent in writing was secured from all participants before enrollment. Demographic and clinical information, such as age, gender, body mass index, smoking habits, hypertension, diabetes, coronary artery disease, heart failure, and prior instances of stroke or transient ischemic attack (TIA), were gathered through a standardized form and hospital medical documentation. The CHA₂DS₂-VASc score was determined for each patient to evaluate initial thromboembolic risk. A comprehensive imaging evaluation of the left atrial appendage was conducted utilizing TEE or CCTA by skilled cardiologists and radiologists. According to defined classification standards, LAA morphology was divided into four categories: chicken wing, cactus, windsock, and cauliflower. Other anatomical parameters, such as LAA depth, orifice diameter, lobes count, left atrial size, and appendage flow velocity, were measured and documented as well. The documentation noted the existence of thrombus in the left atrial appendage and spontaneous echo contrast. The main outcome was the risk of thromboembolism, evaluated through the history of prior ischemic stroke or TIA, the presence of left atrial appendage thrombus, spontaneous echo contrast, and high CHA₂DS₂-VASc scores. All gathered data were inputted into and examined with SPSS version 26.0. Continuous variables were represented as mean ± standard deviation, while categorical variables were shown as frequencies and percentages. The link between LAA shape and thromboembolic risk factors was examined using the Chi-square test and one-way analysis of variance (ANOVA), as applicable. A multivariate logistic regression analysis was then conducted to determine independent predictors of thromboembolic events while adjusting for possible confounding factors. A p-value below 0.05 was deemed statistically significant. Ethical clearance for the research was granted by the Institutional Review Board of Mayo Hospital Lahore, and patient confidentiality was preserved during the study following ethical research protocols

This study conducted at Mayo Hospital Lahore included 200 patients diagnosed with non-valvular atrial fibrillation. The average age of patients was 63.4 ± 10.8 years, with a higher proportion of males (58% males, 42% females). Hypertension was the most prevalent comorbidity (62%), followed by diabetes mellitus (38%), coronary artery disease (27%), and heart failure (22%). The average CHA₂DS₂-VASc score was 3.6 ± 1.4.

Table 1: Baseline Characteristics of Patients (n = 200)

Table 2: Distribution of Left atrial Appendage Morphology

Left atrial appendage thrombus was detected in 18% of patients, while spontaneous echo contrast (SEC) was observed in 34% of cases.

Table 3: Association of LAA Morphology with Thrombus Formation

 Table 4: History of Stroke/TIA According to LAA Morphology

Table 5: Multivariate Logistic Regression Analysis

This research performed at Mayo Hospital Lahore indicated that the morphology of the left atrial appendage (LAA) is strongly linked to thromboembolic risk in individuals with non-valvular atrial fibrillation. Non-chicken wing morphologies, especially cauliflower and cactus forms, exhibited a greater frequency of left atrial appendage thrombus, spontaneous echo contrast, and past ischemic stroke or transient ischemic attack relative to the chicken wing morphology.

The results indicate that variations in LAA anatomy significantly contribute to thrombus formation in addition to traditional clinical risk factors like the CHA₂DS₂-VASc score. Patients exhibiting more intricate and multilobed LAA structures showed slower blood flow dynamics, potentially leading to heightened blood stasis and thrombogenesis.

In conclusion, LAA morphology could act as a useful additional imaging marker to enhance thromboembolic risk assessment in patients with atrial fibrillation. Including LAA morphological evaluation in standard clinical assessments might assist in recognizing high-risk patients who might gain from intensified anticoagulation approaches or the option of left atrial appendage closure procedures.

Additional extensive prospective research is suggested to confirm these results and to create standardized procedures for incorporating LAA morphology into everyday clinical decision-making.

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