Pulse wave amplitude drops help find patients with OSA at risk for cardiovascular events

Key takeaways:

• Use of pulse wave amplitude drop index scores helped identify patients with OSA who face a greater risk for cardiovascular events.
• A heightened risk was found among those with OSA and a low index score.

Having a low pulse wave amplitude drop index was linked to a heightened risk for cardiovascular events in patients with obstructive sleep apnea, according to results published in American Journal of Respiratory and Critical Care Medicine.

Pulse wave amplitude drops (PWADs) indicate sympathetic activations and vascular reactivity, according to researchers.

“These results suggest that adding the PWAD index to [apnea-hypopnea index] provides a better indication of increased cardiovascular risk and may reflect the specific impact of OSA on autonomic and/or vascular reactivity,” Geoffroy Solelhac, MD, head of the Center for Investigation and Research in Sleep, and colleagues wrote. “In patients with OSA who have a higher PWAD index and who may have a lower impact of OSA on their cardiovascular system, good adherence to CPAP treatment appears to have the potential to prevent incident cardiovascular events.”

In this analysis, Solelhac and colleagues assessed individuals from three different sleep study cohorts to see if PWADs can be used as a biomarker for cardiovascular risk in OSA.

Of the three cohorts, the largest was the Pays-de-la-Loire sleep cohort (PLSC), which included 6,367 individuals, followed by the HypnoLaus cohort (n = 1,941) and the ISAACC, or “Impact of Sleep Apnea syndrome in the evolution of Acute Coronary syndrome. Effect of intervention with CPAP,” cohort (n = 692).

Within each group, researchers used pulse oximetry-based photoplethysmography signals to collect PWADs, and the number of drops per hour represented the PWAD index.

The median PWAD index varied based on cohort, with 51.8 drops per hour in the HypnoLaus cohort, 46.9 drops per hour in the PLSC cohort and 39.2 drops per hour in the ISAACC cohort.

Following adjustment for age, sex, BMI, alcohol intake, smoking, diabetes, hypertension, lipid-lowering drugs and vasodilators in the HypnoLaus cohort, researchers found that those with OSA had a similar incidence of cardiovascular events as patients without OSA.

After dividing this cohort based on OSA (with or without) and median PWAD index scores (high or low), the group with the greatest risk for incident cardiovascular events was patients with OSA and a low PWAD index score vs. patients with OSA and a high PWAD score (HR = 2.16; 95% CI, 1.07-4.34), patients without OSA and a high PWAD score (HR = 2.35; 95% CI, 1.12-4.93) and patients without OSA and a low PWAD score (HR = 1.9; 95% CI, 1.02-3.54).

Among those with OSA, researchers found that the risk for incident cardiovascular events decreased with each addition of 10 PWADs per hour (HR = 0.85; 95% CI, 0.73-0.99).

In the PLSC, patients with OSA and a low PWAD index score again faced the greatest risk for major adverse cardiovascular events out of the four groups (with OSA and high PWAD, HR = 1.36; 95% CI, 1.13-1.63; without OSA and high PWAD, HR = 1.44; 95% CI, 1.06-1.94; without OSA and low PWAD, HR = 1.1; 95% CI, 0.88-1.38).

Researchers further observed that the risk for incident cardiovascular events fell with each additional 10 PWADs per hour among patients with OSA in this cohort (HR = 0.91; 95% CI, 0.86-0.96).

Notably, CPAP treatment was given to 3,669 patients in the PLSC, and the risk for incident major adverse cardiovascular events decreased among those with a high PWAD score and use of CPAP for 4 hours or more per night compared with those with a high PWAD score and use of CPAP for less than 4 hours per night (HR = 0.74; 95% CI, 0.55-0.98). Researchers did not find a significant link between greater CPAP adherence and a low PWAD score.

Within the ISAACC cohort, the risk for recurrent cardiovascular events was heightened among those with OSA (treated with usual care) and a low PWAD score vs. those without OSA (HR = 2.03; 95% CI, 1.08-3.81).

Unlike the HypnoLaus cohort and the PLSC, the addition of 10 PWADs per hour in patients with OSA did not significantly change the risk for recurrent cardiovascular events, according to researchers.

Compared with usual care, CPAP use in both PWAD groups did not lower the risk for incident cardiovascular events.

“The fact that similar findings were obtained in different populations (general, clinical and cardiovascular) and that studies that utilized slightly different cardiovascular endpoint outcome definitions suggest a good reproducibility and generalizability of these results,” Solelhac and colleagues wrote.