In patients presenting with embolic stroke and no clear source, the presence of a right-to-left shunt (RLS) due to a patent foramen ovale (PFO) suggests paradoxical embolization as a cause. Studies indicate that endovascular closure of a PFO in select individuals can reduce subsequent stroke risk. Identifying RLS due to PFO is therefore crucial in stroke workup, particularly in young patients without traditional vascular risk factors. Diagnostic tests for RLS and PFO include transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), and transcranial Doppler (TCD), each with its strengths and limitations.

Comparing TCD, TTE, and TEE for RLS Detection

While TTE is noninvasive and highly specific, it has lower sensitivity compared to TEE, which is considered the gold standard but is more invasive and requires sedation. TCD, on the other hand, is noninvasive and correlates well with TEE findings but is less frequently used due to the need for skilled operators. However, advancements like robot-assisted TCD (raTCD) are addressing this by using automation and AI to optimize the detection of RLS, making the test more accessible and reliable even in community settings without specialized personnel.

A recent study by Rubin et al. demonstrated that raTCD was effective in detecting RLS in patients with presumed embolic stroke, showing higher detection rates compared to TTE. This suggests that raTCD could be a valuable tool in identifying patients who might benefit from PFO closure, potentially reducing the risk of subsequent strokes. As the use of raTCD becomes more widespread, it could transform the workflow for PFO screening, providing a noninvasive initial test with positive results confirmed by TEE before proceeding to endovascular closure. For more detailed insights into this study and the implications for stroke prevention, read the full article on Stroke.