In a new study presented at ATS, investigators find CPAP withdrawal worsens the augmentation index.
A team of researchers from Johns Hopkins University examined whether CPAP withdrawal will worsen the augmentation index (AIx) and if the extent of AIx change is influenced by various factors, including obstructive sleep apnea severity, age, body mass index (BMI), sex, and diabetes.
Obstructive sleep apnea has long been linked to arterial stiffness, which is measured by the augmentation index. AIx, which is independently linked to cardiovascular disease and mortality risk, often reflects systemic arterial stiffness.
In the single-center randomized crossover study planned for presentation at the American Thoracic Society (ATS) 2020 International Conference, the investigators examined 69 patients with moderate to severe obstructive sleep apnea acclimated to CPAP.
The patient population was 48 males and 21 females with complete AIx data available. Subjects were aged 50.3 ± 11.3 years, with a BMI of 36.6 ± 7.5 kg/m2.
Each patient underwent a polysomnography while sleeping with therapeutic CPAP or without CPAP following 2 days of CPAP withdrawal.
The investigators assessed morning arterial stiffness by EndoPAT to determine the augmentation index—normalized to a heart rate of 75 b/min. They then compared the AIx of subjects on and off CPAP using paired t-tests and examined the change in the augmentation index as a function of continuous variables using Pearson correlations models (Δ AHI 3%, age, BMI).
Finally, they used 2-way ANOVA to examine the effects of categorical variables (sex and diabetes) and their interaction with CPAP on AIx.
Ultimately, the researchers found CPAP withdrawal yielded severe obstructive sleep apnea. The AHI 3% on CPAP and off CPAP was 5.8 ± 0.9 and 57.3 ± 3.6 events/hr, respectively, while arterial stiffness also worsened with CPAP withdrawal. The augmentation index on CPAP and off CPAP was 6.8 ± 2.06 and 2.8 ± 1.9% (mean ± SE) respectively (P = 0.0001) and the Δ AIx following CPAP withdrawal was not correlated with Δ AHI 3%, age, or BMI.
While women had a higher augmentation index overall than men, the change in AIx response to CPAP withdrawal was similar. The investigators also found diabetes did not influence AIx or the magnitude of change in response to CPAP withdrawal.
In another study presented at ATS, investigators from Yale University found that sodium glucose co-transporter (SGLT)-2 inhibitors could help reduce some of the negative cardiovascular outcomes for patients with type 2 diabetes and obstructive sleep apnea.
In the randomized placebo-controlled outcome study, dubbed the EMPA-REG OUTCOME trial, the investigators examined 7020 patients from 42 countries with type 2 diabetes and cardiovascular disease.
The investigators found empagliflozin reduced HbA1c, systolic blood pressure, waist circumference, and weight, while also reducing the risk of three-point major adverse cardiovascular events (3P-MACE) by 14% and cardiovascular death by 38%. The treatment also resulted in a 35% reduction in hospitalization for heart failure.
However, the Johns Hopkins University shows that CPAP withdrawal could result in worsened cardiovascular outcomes.
“CPAP withdrawal acutely worsens AIx, with significant heterogeneity between subjects,” the authors wrote. “OSA severity, age, BMI, sex, and diabetes do not predict AIx or its change during CPAP withdrawal.”
The study, “Withdrawal from Continuous Positive Airway Pressure (CPAP) Worsens Morning Arterial Stiffness,” was published online by the ATS International Conference.