From the Journals

Report touts PFO closure in divers; experts disagree


 

FROM JACC

A new report recommends the surgical closure of patent foramen ovale (PFO) in high-risk divers, but physicians in the United States urged caution about widespread use of the procedure in this population.

“PFO closure is recommended in divers with a high-grade PFO, with a history of unprovoked decompression sickness [DCS], or at the diver’s preference. Besides protection from DCS, PFO closure also offers the diver life-long protection from PFO-associated stroke,” write the authors of an analysis of the DIVE-PFO Registry.

The investigators, led by Jakub Honêk, MD, PhD, of Motol University Hospital in Prague, based that advice on results of their analysis, which compared two groups of divers with high-grade PFO: 55 who underwent catheter-based PFO closure, and 98 who were urged to dive cautiously.

Over a mean of about 7 years, the divers who underwent catheter-based PFO closure had no unprovoked decompression sickness (DCS), while the condition occurred in 11% of those who hadn’t had the procedure, according to the report, a research letter published online in the Journal of the American College of Cardiology.Decompression sickness, also known as the bends, can occur as gas bubbles pass through the circulatory system as divers ascend. In divers with PFO, which affects about 25% of the population, the bubbles can bypass filtration in the lungs and cause strokes, said neurologist David Thaler, MD, PhD, of Tufts Medical Center, Boston.

PFO closure via surgery is one option for divers with PFO, but there’s debate over whether the procedure should be widespread. For the new research letter, researchers prospectively tracked 748 divers in the DIVE-PFO (Decompression Illness Prevention in Divers with a Patent Foramen Ovale) registry during 2006-2018. Twenty-two percent had high-grade PFO.

In divers with PFO of grade 3 or above, procedures were performed if patients had a history of DCS or if they couldn’t adapt to conservative diving recommendations. The researchers said this population included commercial divers.

The groups that did or didn’t undergo surgery were similar in age (40.0 and 37.3 years, respectively, P = 0.079), and sex (78.2% and 79.6% male, respectively, P = 0.893), but differed in number of new dives (30,684 vs. 25,328, respectively, P < 0.001,), ). They were tracked for a mean of 7.1 years and 6.5 years, respectively.

It’s not clear whether the divers who underwent the closure procedure had fewer DCSs because they were more cautious about dive safety than the other diver group. The research letter doesn’t mention whether strokes occurred in divers in the two groups.

The study authors write that the results are consistent with previous findings that “PFO closure eliminates arterial gas emboli, “PFO is a major risk factor for unprovoked DCS,” and “PFO closure is a safe procedure with a very low complication rate.”

In interviews, physicians who are familiar with diver safety questioned the value of the findings and said medical professionals shouldn’t change practice.

Not so fast, experts say

Dr. Thaler, the Tufts Medical Center neurologist, questioned why the report explored a link between PFO and DCS. Overall, he said, the findings are too incomplete to inform practice. Anesthesiologist Richard Moon, MD, of Duke University, Durham, N.C., also questioned the study’s examination of DCS. “Most DCS cases are uncorrelated with PFO. It is only serious cases, a minority, that could conceivably be related to PFO, and even then, many serious cases that occur in divers with PFO are unrelated to it.” He added that “numerous divers with mild DCS ... have been mistakenly evaluated for PFO. Such practice is unsubstantiated by data.”

Should more closures be performed in this population? “I would be hesitant to make the recommended closures in divers,” said cardiologist David C. Peritz, MD, of Dartmouth-Hitchcock Medical Center, Lebanon, N.H. “There are probably other ways that you can decrease your chances of getting decompression illness and make your dives more safe.”

Cardiologist Clifford J. Kavinsky, MD, PhD, of Rush University Medical Center, Chicago, said the closure procedure is “relatively safe” when performed by experienced surgeons. He noted that it is “only approved to prevent recurrent ischemic stroke in patients predominantly between the ages of 18 and 60 years who have experienced a cortical stroke presumed to be of embolic nature and for which no obvious cause can be found.”

As for high-risk divers, he said PFO closures “can be considered, but the data as yet are not strong enough to strongly recommend it.”

The Czech Republic’s Ministry of Health funded the study. The authors report no relevant disclosures. Dr. Thaler, Dr. Kavinsky, Dr. Moon and Dr. Peritz report no relevant disclosures.

SOURCE: Honěk J et al. J Am Coll Cardiol. 2020 Sep 1;76(9):1149-50.

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