Loading ...

According to a study published in the European Heart Journal, continuous positive airway pressure (CPAP), a treatment commonly used for obstructive sleep apnea (OSA), reduces the risk for serious cardiovascular (CV) events in some patients, but not in others.

Ali Azarbarzin, PhD, of Brigham and Women’s Hospital and Harvard Medical School in Boston and the senior author of the study, told Medscape’s French edition: “Our findings suggest that CPAP may offer long-term cardiovascular benefits in people with high-risk obstructive sleep apnea, but it may have unintended harmful effects in those who do not have high-risk OSA.”

Addressing the Uncertainty

OSA causes not only fatigue but may also increase the risk for high blood pressure, stroke, and heart disease in affected individuals. The primary treatment is CPAP therapy.

“We knew OSA is linked to cardiovascular disease, but clinical trials of OSA treatment with CPAP have not demonstrated long-term CV benefits so far,” Azarbarzin explained. “This creates uncertainty about whether all individuals with OSA need treatment.”

To address this uncertainty, he and his team pooled results from three separate trials testing CPAP in people with OSA. This allowed them to study a larger group and analyze data according to different patient subgroups.

Three-Year Average Follow-Up

In total, the study included 3549 people with OSA and CV disease, about half of whom used CPAP devices while the other half did not. All patients were tested at the start of the trials to confirm OSA diagnosis. Patients were followed for an average of 3 years, and all cases of heart attack, stroke, or death due to CV disease were recorded.

“Previously, these trials studied the overall effect of CPAP without considering the fact that in some people OSA causes severe drops in the level of oxygen in the blood or large surges in heart rate, known as high-risk OSA, but in others it does not,” a press release from the European Society of Cardiology explained.

In the new study, the researchers’ analysis showed that the effect of CPAP treatment was greater in participants with high-risk OSA than in those without it [interaction hazard ratio, 0.69]. In patients with high-risk OSA, CPAP reduced the risk for heart attack, stroke, and CV death by approximately 17%, representing a 31% greater effect than in patients without high-risk OSA. However, in the latter group, CPAP may increase the risk for serious CV events by about 22%.

Focusing on Those Who Stand to Benefit Most

When researchers looked specifically at patients without daytime sleepiness, the results were even more pronounced. In these patients, CPAP reduced CV risk by 24% in those with high-risk OSA but increased CV risk by 30% in others.

“For people with high-risk OSA, CPAP likely helps prevent low oxygen levels and calms an overactive sympathetic nervous system during sleep. Both factors are linked to cardiovascular disease. But in people without these high-risk markers, who already have a very low CV risk, CPAP seems to have downsides,” Azarbarzin noted.

“Although we do not yet fully understand why, one possibility is that the pressure used in CPAP may stretch the lungs in a way that puts strain on the cardiovascular system. Another possibility is that CPAP may disrupt sleep in some individuals, and sleep disturbances are themselves a risk factor for cardiovascular problems. Further research is needed to understand these mechanisms.”

“Our findings suggest a more personalized approach to treating OSA. Instead of treating everyone the same way, we should examine whether a person has high-risk features,” he continued. “These are the people who appear most likely to benefit from CPAP. For clinicians and policymakers, this means we may need to rethink current recommendations for treating nonsleepy patients and consider focusing cardiovascular risk reduction treatment on those who stand to gain the most. We should also be cautious in using CPAP in people without high-risk markers, as they may not benefit and could even experience harm.”

“Adverse effects related to CPAP were only observed in nonsleepy patients with existing heart disease, according to the design of the trials analyzed in this study. It is unknown whether this applies to other patients, and further research is needed.”

To confirm their findings, Azarbarzin and colleagues plan to conduct a new clinical trial focused on patients with high-risk OSA. They are also studying how and why CPAP may cause adverse effects in those without high-risk OSA and exploring alternative treatments for OSA to reduce CV risk.

Two New Findings Worth Noting

In an editorial accompanying this study, Andrea Natale, MD, of the Texas Cardiac Arrhythmia Institute in Austin, and colleagues stated: “OSA has been reported to increase the risk of heart failure by 140%, the risk of stroke by 60%, and the risk of coronary heart disease by 30%.”

Three major randomized controlled trials (RCTs) — ISAACC, RICCADSA, and SAVE — conducted between 2016 and 2020, published their evaluations of CPAP’s effect on long-term CV complications in patients with OSA and preexisting CV comorbidities. Each of these RCTs demonstrated CPAP treatment was ineffective in reducing CV risk in patients with moderate-to-severe OSA and minimal or no daytime sleepiness.

By pooling individual patient data from these three RCTs, “The current study reported two novel findings that are worth mentioning,” they wrote. “First, the authors demonstrated a harmful impact of CPAP in ‘low-risk OSA’ patients that included all except those with a heart rate response > 9.4 beats/min or a hypoxic burden > 87.1%. The possible underlying mechanism for this observation is, however, unclear. Second, they documented CPAP benefits only in high-risk individuals, especially those without excessive sleepiness and/or hypertension.”

This story was translated from Medscape’s French edition.