Classification system shows which patients would benefit from PFO closure

Phoebe Dow tied the knot with Travis Keeter in December 2020 – 15 years after she suffered a PFO-associated stroke and participated in a life-saving trial at UTHealth Houston. (Photo courtesy of Phoebe Dow)

Richard Smalling, MD, PhD, professor and the James D. Woods Distinguished Chair in Cardiovascular Medicine with McGovern Medical School at UTHealth Houston.

Sixteen years ago, Phoebe Dow was a 19-year-old waitress when she suffered a stroke resulting from a common birth defect – a small hole between the top two chambers of the heart, which can sometimes allow a blood clot to travel through the hole and up into the brain.

Today, Dow is a 35-year-old newlywed and accountant who hasn’t had any issues with her heart since the November 2005 incident, thanks to a patent foramen ovale (PFO) closure performed by Richard Smalling, MD, PhD, professor and the James D. Woods Distinguished Chair in Cardiovascular Medicine with McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth Houston).

“I’m fortunate that Dr. Smalling got to me when he did – it was a ‘right place, right time’ kind of thing,” Dow said. “Not everyone benefits from a PFO closure, but I certainly have. For me, it was a life-saving treatment.”

Dow was among nearly 1,000 patients to participate in a national, randomized clinical trial – known as the RESPECT trial – led locally by Smalling, which over the course of 12 years compared outcomes between patients who received the PFO closure with medical therapy versus patients who received medical therapy alone. The results from this trial and five others conducted globally from 2000-2017 were analyzed in a paper recently published in The Journal of the American Medical Association, which was co-authored by Smalling and 21 others.

The JAMA study found that the application of a multivariable, causal classification system to these trial results could distinguish patients who may benefit from PFO closure from those unlikely to benefit.

“Hopefully, this will increase the number of PFO-associated stroke patients who have access to therapy,” said Smalling, who is also director of Interventional Cardiovascular Medicine in the Division of Cardiology with McGovern Medical School and a cardiologist at Memorial Hermann-Texas Medical Center.

PFO-associated strokes comprise approximately 10% of all ischemic strokes in adults ages 18 to 60. In a PFO closure, a device, often guided by a catheter, is moved through a vein in the upper part of the leg to the location of the defect in the heart. The device is deployed to seal the hole and remains in the heart permanently, effectively stopping clots which have formed in the legs or pelvic regions from reaching the brain.

To determine which patients would benefit from the procedure, researchers used the Risk of Paradoxical Embolism (RoPE) Score, a 10-point scoring system in which higher scores reflect younger age and the absence of vascular risk factors like atrial fibrillation, and the PFO-Associated Stroke Causal Likelihood (PASCAL) Classification System, which combines the RoPE Score with high-risk PFO features – either an atrial septal aneurysm (an unusually mobile part of the wall between the two upper chambers of the heart) or a large-sized shunt – to classify patients into three categories of the risk of stroke related to the patient’s anatomy: unlikely, possible, or probable.

Among patients 18 to 60 years old with a PFO-associated stroke, in patients whose stroke was classified as “possibly” or “probably” related to the PFO, there was a reduced risk for a second stroke after the device closure, making them most likely to benefit from the procedure.

According to Smalling, the classification system is significant because, while PFO closures were already known to decrease overall risk of stroke recurrence, the best treatment for any individual is often unclear. He hopes these findings will put physicians nationwide more at ease and confident about recommending the procedure for their patients with PFO-associated stroke.

“This study puts a lot of objectivity into the decision-making process for physicians and patients,” Smalling said. “What it shows is that, in patients who have had a stroke, if you’re young and you have an atrial septal aneurysm or a large shunt, you need to get your PFO closed to prevent additional strokes.”

The findings come more than five years after the Food and Drug Administration in 2016 approved the PFO treatment for use in all patients, thanks in part to testimony given by Dow and several other patients who found it successful. With the latest study, Dow hopes even more stroke patients will become aware of the treatment as a potential option.

Dow has come a long way since her stroke. She graduated from Sam Houston State University in 2014 with an accounting degree and has been working with the same employer for 11 years. In December 2020, she got married, and she now lives with her husband in Cypress, ready for what the future holds.

“When I had that stroke, it woke me up and made me realize to take my life more seriously,” Dow said. “At the time, I didn’t have a lot of other options, but looking back, I would’ve made the same choice to join the trial anyway. It makes me feel good that today, I’m still able to make a difference somehow.”

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