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Patent foramen ovale (PFO) is common in intermediate-risk pulmonary embolism, highly correlated with stroke, and perhaps best found with transesophageal echocardiography (, a small study suggested.

Contrast whereas transthoracic echocardiography (TTE) picked up these shunts in only 19.5% of the 41 consecutive patients with intermediate risk PE who got both types of imaging at a single center (P<0.001).

TEE didn't miss any cases found on TTE, making it "more efficient than TTE for PFO diagnosis," Denis Doyen, MD, of Pasteur University Hospital in Nice, France, and colleagues found.

Notably, MRI-confirmed ischemic stroke occurred in 17.1% and was always associated with PFO and large shunt, the group reported in the October issue of Chest.

"Considering the high risk of intracranial bleeding with thrombolysis in pulmonary embolism, which may be partly due to hemorrhagic transformation of subclinical strokes, screening PFO with TEE should be considered in intermediate-risk PE when thrombolytic treatment is discussed," they recommended.

In their prospective study, TEE showed a large shunt in 39.0% of patients (69.6% of those with PFO), whereas that rate was 12.2% by TTE (P=0.001).

TEE revealed PFO in all seven of the patients who had a stroke, while TTE diagnosed a PFO in just three of the seven (P=0.046).

"In other words, TTE failed to identify PFO in four of seven patients presenting with stroke," the researchers wrote. "In all, 30.4% of all patients with PFO diagnosed using TEE had a stroke."

"None of these patients exhibited significant carotid stenosis on carotid duplex ultrasound, aortic stenosis on TEE, or cardioembolic arrhythmia. They did not have more cardiovascular risk factors than other patients."

One possible explanation for the high PFO rate in the study offered by the researchers was if "overall elevated right-sided heart pressures lead to a reopening of PFO."

Thus, the mean 2-day delay in performing the TEE contrast study was a limitation of the study, as PFOs might have closed with a drop in pulmonary pressure.

The findings now need to be confirmed in larger cohorts, Doyen's group noted.

Transcranial Doppler could also be tried for PFO screening, although the lower specificity than TEE might be a counterpoint to the noninvasiveness, the group suggested.

Prior studies that have shown PFO to be an independent predictor of silent brain infarcts have mainly examined low-risk pulmonary embolism patients and used TTE, they pointed out.

From the American Heart Association:

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