Derek Chang, University of Utah
Atrial fibrillation (AF), the most common cardiac arrhythmia, is a rapid, irregular heart beat arising from uncontrolled and asynchronized electrical activation in the atria. This disruption of the normal electrical signaling hinders the contraction of the heart, leading to decreased blood flow, possible clot (thrombus) formation, and an increased risk of stroke. The left atrial appendage (LAA) is a small muscular pouch of highly variable anatomy within the left atrium. The LAA plays a prominent role in thrombus formation in patients with AF because of decreased blood flow within this structure. Thus, we hypothesized that the shape of the left atrial appendage is different in AF patients with a documented history of stroke. We used statistical shape analysis to determine which LAA shape variations contribute to stroke based on a cohort of AF patients who had both MRI and CT scans and a documented history of stroke. We manually delineated the boundaries of the LAA from each patient’s CT and MRI scans to analyze the resulting LAA segmentations for shape variations across imaging modalities and history of stroke. The results showed that patients who have AF and a history of stroke have an LAA with a narrower insertion site into the left atrium and are larger in size. In contrast, patients who have AF, but no history of stroke, have an LAA with a wider insertion site, which are smaller in size. By isolating specific LAA shape variants indicative of an underlying risk of stroke, we can use this shape classification scheme to better tailor AF therapies to each individual patient.