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Closing patent foramen ovale eases oxygen desaturation during exercise

NEW YORK (Reuters Health) – Percutaneous closure of a patent foramen ovale (PFO) ameliorates oxygen desaturation during stair exercise and improves functional status, researchers say.

“There is a lot about patent foramen ovale that we still don’t understand,” Dr. Richard A. Krasuski from the Cleveland Clinic in Ohio told Reuters Health in an email. “It is a very common lesion and has been implicated in a number of different pathophysiologic states. There appear to be some patients who have exercise limitation due to their PFO, and this population may benefit from closure.”

As reported last month in JACC: Cardiovascular Interventions, Dr. Krasuski and colleagues examined the prevalence of provoked exercise desaturation (PED) in 50 patients referred for cardiovascular recommendations with regard to PFO management and investigated the impact of PFO closure on those patients exhibiting PED.

Seventeen patients experienced a desaturation of at least 8% to values below 90%, thereby meeting the criteria for PED.

Four of the 17 patients with PED had been referred primarily due to arterial oxygen saturation, but the other 13 had no documented history of oxygen desaturation.

Thirteen patients with PED underwent PFO closure, and 10 of these completed follow-up three months later.

Among these 10 patients, oxygen saturation during exercise improved by an average of 10.1%, and NYHA functional class improved by a median of 1.5 classes.

The presence of a residual shunt after PFO closure did not seem to affect its efficacy in ameliorating PED.

“These findings are the first to validate the important mechanistic role that PFO plays in the pathophysiology of the transient desaturation observed in patients during stair exercise and suggest that PFO closure might be an effective strategy for improving arterial desaturation and functional status in patients with PED,” the researchers wrote.

Dr. Krasuski added, “If such a patient with PFO and documented right to left shunt is exercised and drops their oxygen saturation while developing shortness of breath, I believe that it is reasonable to consider closure, but this should only occur after a very thorough clinical evaluation including pulmonary function testing and a visit to the pulmonologist. I would also recommend a very thorough evaluation for pulmonary hypertension before device closure with a careful right heart catheterization and measurement of the cardiac output to ensure that it is normal. If there is pulmonary hypertension present, device closure can be detrimental and even lethal.”

“The CLOSURE study has appropriately dampened enthusiasm about device closure for initial stroke for the time being,” Dr. Krasuski said, “and we should certainly be focusing our efforts to recruit patients with stroke or migraine headache into randomized clinical studies of device closure to better grow our evidence base.”

In a related editorial, Dr. Bernhard Meier from Bern University Hospital in Switzerland offers a qualified agreement. “I suggest that we look for a PFO in patients complaining about unexplained exertional dyspnea and to close it when present,” he writes, “crossing our fingers that the symptoms will improve.”

“Should we go as far as to test symptomatic PFO carriers for provoked exercise desaturation as described? Probably not,” Dr. Meier concludes, “as we usually have a more compelling indication at hand.”

SOURCE: http://bit.ly/IIDp4O

J Am Coll Cardiol Intv 2012;5:416-419.