What is a reasonable imaging modality for older patients with pAfib already on systemic anticoagulation outpatient but presenting with suspected cardioembolic stroke and TTE without evidence of LV thrombus?

Gold standard is TEE.

The prevalence of left atrial appendage thrombus despite anticoagulation for atrial flutter or fibrillation is around 3% (Lurie et al., PMID 34112315). This is likely due to ineffective doses of anticoagulation, medication noncompliance, or the presence of severe atrial myopathy in conditions such a...

TEE is reasonable to evaluate for other sources of emboli or risk for emboli, such as left atrial smoke, PFO, vegetations, tumors, thrombus, or aortic atheroma in a patient who has apparently failed anti-coagulation.