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CPAP Selectively Reduces VCAM-1 but Not ICAM-1 or PAI-1 in CAD Patients With OSA
In a 12-month randomized controlled trial, CPAP therapy was associated with a significantly greater reduction in vascular cell adhesion molecule-1 (VCAM-1) compared with no treatment, reaching statistical significance on the time-by-treatment interaction (p = 0.045 in adjusted models), while intercellular adhesion molecule-1 (ICAM-1) showed no meaningful change and plasminogen activator inhibitor-1 (PAI-1) produced only a borderline trend (p = 0.09). The pattern suggests that CPAP exerts pathway-specific effects on vascular biology rather than broad suppression of endothelial or prothrombotic activity in this high-risk cardiac population.
What Was Studied
This analysis examined whether continuous positive airway pressure (CPAP) therapy could favorably modify circulating markers of endothelial activation and fibrinolytic balance over 12 months in patients who already carry an established cardiovascular diagnosis. The specific biomarkers targeted — ICAM-1, VCAM-1, and PAI-1 — were chosen because intermittent hypoxia, oxidative stress, and systemic inflammation associated with obstructive sleep apnea are understood to drive both endothelial adhesion molecule expression and a prothrombotic state, mechanisms thought to accelerate atherosclerosis progression.
How It Was Studied
This was a prespecified randomized controlled analysis embedded within the RICCADSA trial, enrolling 210 patients who had undergone coronary revascularization and carried a diagnosis of moderate-to-severe obstructive sleep apnea. Participants were allocated to receive CPAP (n = 104) or no CPAP (n = 106) and were followed for 12 months with biomarker measurements collected at baseline and endpoint. Circulating levels of ICAM-1, VCAM-1, and PAI-1 were quantified, and longitudinal changes were analyzed using linear mixed-effects models that incorporated time-by-treatment interaction terms and adjustment for relevant cardiometabolic covariates, providing a robust statistical framework for detecting differential trajectories between the two arms.
What Was Observed
- VCAM-1 was significantly reduced in the CPAP group relative to controls. The time-by-treatment interaction reached conventional statistical significance (p = 0.045) in adjusted models, indicating that CPAP was associated with a meaningfully greater attenuation of this endothelial adhesion molecule over the 12-month period compared with no intervention. This suggests that at least one dimension of endothelial activation is modifiable with CPAP in revascularized patients.
- ICAM-1 showed no statistically significant difference between groups. No meaningful time-by-treatment interaction was detected for this adhesion molecule, indicating that CPAP did not selectively alter circulating ICAM-1 levels, and pointing to a dissociation between the two endothelial adhesion pathways in their responsiveness to airway pressure therapy.
- PAI-1, a marker of fibrinolytic imbalance, showed only a borderline trend favoring CPAP. The time-by-treatment interaction for PAI-1 was p = 0.09, meaning the numerically smaller increase observed in the CPAP group did not reach statistical significance. The fibrinolytic axis therefore appeared largely resistant to CPAP-mediated modification under the conditions of this trial.
Why This Matters
OSA is recognized in this study as a driver of endothelial activation and prothrombotic physiology through intermittent hypoxia and inflammation — mechanisms directly implicated in atherosclerosis progression among patients with established coronary artery disease. The finding that CPAP selectively attenuates VCAM-1 but leaves ICAM-1 and PAI-1 largely unchanged implies that vascular responses to CPAP are pathway-specific rather than uniformly beneficial. This selectivity may partly explain why residual atherosclerotic risk persists in CAD patients with OSA despite airway treatment, and it identifies fibrinolytic dysregulation as a potentially distinct therapeutic target not adequately addressed by CPAP alone.
How to Read This Result
While this high-quality randomized trial provides mechanistically informative signal supporting selective VCAM-1 reduction with CPAP, the borderline PAI-1 result (p = 0.09), absence of effect on ICAM-1, and the modest sample size of 210 participants collectively mean the full scope of CPAP’s vascular impact in this population remains incompletely characterized and should be interpreted with appropriate caution.
Limitations
The abstract does not explicitly report study limitations.