Abstract P328: Transcranial Doppler as a Cost-Effective, Safe Screening Tool in Embolic Stroke of Undetermined Source

Abstract

The diagnostic evaluation of embolic stroke of undetermined source (ESUS) requires investigation of paradoxical embolism via shunts. ESUS evaluation involves a transthoracic echocardiogram (TTE) with saline contrast study, then a transesophageal echocardiogram (TEE) for further evaluation of a patent foramen ovale (PFO), as TTE lacks sensitivity. PFO closure is offered for significant shunts. TEE is the gold standard but transcranial doppler (TCD) may help in the ESUS algorithm for shunts. TCD reduces procedural and anesthetic risk to patients, may be cost-effective, and mitigates risk to providers during the COVID-19 pandemic (1-2). Studies have shown the accuracy of TCD with microbubble for the diagnosis of shunts compared to TEE; a recent meta-analysis found weighted average sensitivity and specificity of 97% and 93%, respectively (3). We propose introducing TCD into the algorithm to evaluate ESUS as a screening tool with similar fidelity to TEE. According to our algorithm, patients under the age of 60 years with ESUS will undergo TTE with microbubble, then those at low risk of valvular disease or cardiac structural pathology will undergo TCD-emboli protocol. Patients with grade 0-2 shunts will receive medical therapy, while shunt grades 3-5 will be referred for intraoperative TEE and closure. We reviewed records of a TCD-emboli protocol followed by TEE from 2014-2020 to ensure similar validity to published data. The sensitivity and specificity of shunt detection amongst 34 patients with ESUS was 94.7% (CI 73.9% - 99.9%) and 93.3% (68.1%-99.8%), respectively. Cost-benefit analysis of patients who received TCD prior to TEE was calculated as the average cost difference. We calculated a conservative estimate of $2741-$3649 in cost reduction per patient, excluding the cost of TEE anesthesia. In conclusion, TCD-emboli protocol is a cost-effective and safe screening tool with high accuracy in comparison to TEE in the diagnostic evaluation of ESUS.