Ballantyne B, et al. - Given the association of amyloidosis with poor prognosis and that patients with cardiac involvement have particularly poor outcomes, researchers here present a 42-year-old male patient with familial transthyretin amyloidosis who experienced an embolic stroke originating from a left atrial appendage thrombus in the absence of any documented atrial fibrillation. Given the clinical presentation of stroke due to left atrial appendage thrombus without documented AF, this case is unique. As per this case, patients with cardiac amyloidosis exhibit atrial mechanical dysfunction and better stratification of thrombotic risk is required in this population with the integration of echocardiographic parameters and transesophageal echocardiography.