Hyperbaric oxygen may improve heart function in long COVID

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Hyperbaric oxygen therapy (HBOT) increased markers of cardiac function in a small randomized, controlled trial of patients with long COVID.

Patients with reduced left ventricular global longitudinal stress (GLS) at baseline who received HBO had a significant increase in GLS compared to those who received sham treatment.

GLS is a measure of systolic function that is considered a predictor of heart failure-related outcomes.

The study also showed that overall work efficiency (GWE) and global work index (GWI) increased in patients treated with HBOT, but not significantly.

“HBOT is an effective treatment for diabetic foot ulcers, decompression sickness in divers, and other conditions, such as cognitive impairment after stroke“, said Marina Leitman, MD, of the Sackler School of Medicine, Tel Aviv, Israel. lecoeur.org | Medscape Cardiology. His team too studied HBOT in asymptomatic elderly patients and found that the treatment appeared to improve left ventricular end-systolic function.

“We should open our minds to consider this treatment for another indication,” she said. “This is the basis of precision medicine. We have this treatment and know that it can be effective for cardiac pathology.

“Now we can say that patients with post-COVID syndrome should probably be evaluated with echocardiography and GLS, which is the main parameter that showed improvement in our study,” she added. “If the GLS is below normal values, these patients may benefit from HBOT, although further research is needed to determine the optimal number of sessions.

Leitman presented the study May 10 at the European Association of Cardiovascular Imaging (EACVI) 2023, a scientific congress of the European Society of Cardiology.

Changes in biomarkers

The study recruited 60 hospitalized and non-hospitalized post-COVID syndrome patients with persistent symptoms for at least 3 months after having mild to moderate symptomatic COVID-19.

Participants were randomized to receive HBO or a sham procedure five times a week for 8 weeks, for a total of 40 sessions. They underwent echocardiography at baseline and 1–3 weeks after the last session to assess GLS.

The HBOT group received 100% oxygen through a mask at a pressure of 2 atmospheres for 90 minutes, with air breaks of 5 minutes every 20 minutes.

The fictitious group received 21% oxygen by mask at 1 atmosphere for 90 minutes.

At baseline, 29 participants (48%) had reduced GLS, despite a normal ejection fraction, Leitman said. Of these, 16 (53%) were in the HBOT group and 13 (43%) were in the sham group.

The mean GLS at baseline for all participants was -17.8%; a normal value is about –20%.

In the HBO group, GLS increased significantly from -17.8% at baseline to -20.2% after HBO. In the sham group, the GLS was -17.8% at baseline and -19.1% at the end of the study, with no statistically significant difference between the two measurements.

Additionally, the GWE increased overall after HBOT from 96.3 to 97.1.

Leitman’s poster showed GLS and myocardial work indices before and after HBOT in a 45-year-old patient. Before treatment, the GLS was -19%; GWE was 96%; and GWI was 1833 mm Hg.

After HBOT treatment, the GLS was -22%; GWE, 98%; and GWI, 1911 mmHg.

Uncertain clinical relevance

Scott Gorenstein, MD, associate professor in the Department of Surgery and medical director of Wound care and Hyperbaric Medicine and NYU Langone–Long Island, New York, commented on the study for lecoeur.org | Medscape Cardiology.

“The approach is certainly worth investigating, but the benefit is difficult to assess,” he said. “We still don’t understand the mechanism of long COVID, so it’s hard to go from there to say that HBOT will be an effective therapy.”

That said, he added, “This is probably the best study I’ve seen in that it’s a randomized controlled trial, rather than a case series.”

Nevertheless, he noted, “We have no idea from this study if the change in GLS is clinically relevant. As a clinician, I cannot say now that HBOT will improve heart failure secondary to long COVID. We don’t know if the participants were New York heart failure class 3 or 4, for example, and all of a sudden they went from really sick to really well.”

“There are many interventions that can alter markers of cardiac function or inflammation,” he said. “But if they don’t make a difference in terms of quantity or quality of life, is the treatment really helpful?”

Gorenstein said he would have no problem treating a patient with mild to moderate COVID-related heart failure with HBOT, since his own team study conducted near the start of the pandemic showed that it was safe. “But HBOT is an expensive treatment in the United States and there are still risks and side effects, although very, very small.”

The study received no funding. Leitman and Gorenstein disclosed no relevant financial relationship.

European Association for Cardiovascular Imaging (EACVI) 2023. Presented May 10, 2023.

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