Abstract WP260: Evaluation of Transcranial Doppler as a Screening Tool for High Embolic Risk Patent Foramen Ovale in Cryptogenic Stroke

Abstract

Background: Identifying high embolic risk patent foramen ovale (PFO) from the innocent bystanders has become important in the evaluation of patients with cryptogenic stroke (CS) since the recent clinical trials showed the benefits of the closure of PFO on the prevention of recurrent stroke. Transesophageal echocardiography (TEE) is a gold standard to diagnose and evaluate the risk of PFO, but the tolerability and cooperation of handicapped stroke patients limit clinical applications. In this study, we aimed to evaluate the predictability of transcranial Doppler (TCD), a test deemed more feasible to stroke patients than TEE, in diagnosing high-risk PFO on TEE. Methods: We reviewed the data of 485 patients with CS who underwent TEE and TCD to evaluate PFO. To classify the shunts, we applied a 5-level visual classification for TCD either at rest or during Valsalva maneuver (VM): no occurrence of micro-embolic signals; grade I, 1-10 signals; grade II, 11-30 signals; grade III, 31-100; grade IV, 101-300; grade V, >300. High-risk PFO on TEE is defined as PFO with atrial septal aneurysm, hypermobility (phasic septal excursion into either atrium ≥10 mm), or PFO size (maximum separation of the septum primum from the secundum) ≥2 mm. Receiver operating characteristic (ROC) curve was used to determine the threshold value of TCD shunt grade for high-risk PFO which was demonstrated by TEE. Results: Concordant results between TCD and TEE appeared at 344 patients; present of shunt in 235 patients, and no-shunts in 109 patients. Patients with high risk PFO on TEE were detected in 133 among the 238 patients that were PFO positive on TEE. The proportion of high-risk PFO dramatically increased in accordance to the increase in TCD grade with VM. The best cut-off point of TCD grade with VM for detecting high risk shunt was grade III with an area under the curve (AUC) of 0.79, sensitivity of 73.1%, and specificity of 75.6% TCD with VM missed only 2 patients as having PFO among the 133 patients with high-risk PFO on TEE. Conclusions: This study showed that the findings of TCD on the diagnosis and evaluation of the risk of PFO were well correlated with those of TEE. Negative of shunt on TCD can exclude the possibility of high risk PFO; grade III or more on TCD suggests the presence of high risk PFO in patients with CS.