Grading Right-to-Left Shunt With Transforaminal Doppler: A Valid Approach in Patients With Cryptogenic Stroke

Right-to-left shunt (RLS), usually related to a patent foramen ovale (PFO), is an important cause of cryptogenic stroke (CS) in young patients. Transcranial Doppler (TCD) with an agitated saline bubble study is a highly sensitive modality for RLS diagnosis using a transtemporal approach (TTD). However, a minority of patients have insufficient temporal bone windows. We aimed to evaluate the accuracy of transforaminal TCD (TFD) for RLS diagnosis.

We included patients with CS or transient ischemic attack who were tested in the standard protocol for RLS between March 2022 and February 2023. We evaluated the concordance of RLS grades between TFD and transesophageal echocardiogram (TEE) using the weighted kappa index. We also compared TTD and TFD approaches.

Forty patients were included (66.7% men; median age 49 years). Medium or large RLS were found in 28 patients (70%) with TTD and in 27 patients with TFD (67.5%). Through TEE, 19 (82.6%) medium or large PFO were confirmed, and a high agreement rate of 0.684 (p = 0.0003) was observed for grading RLS. Moreover, the agreement rate of RLS grade between TTD and TFD was 0.73 (p < 0.0001).

TFD is a valid approach for RLS diagnosis, with substantial concordance with TEE in grading RLS. Our study found a good grade of agreement between TFD and TEE. Therefore, the value of TCD goes beyond quantifying RLS and could assist in identifying the patients with the largest RLS, who would gain the greatest benefit from PFO closure.