Predictive value of decreased pulse wave amplitude decrease for cardiovascular risk stratification in obstructive sleep apnea

Obstructive sleep apnea elevates cardiovascular risk, but existing biomarkers fail to capture sleep-specific hemodynamic changes. This study evaluates the pulse wave amplitude decrease index, a photoplethysmography-derived measure of vascular/autonomic reactivity during respiratory events, in 1,034 suspected obstructive sleep apnea patients. Each 1-unit pulse wave amplitude decrease index increase reduced major adverse cardiovascular events risk by 2.6% (HR 0.974, 95%CI 0.953–0.995), with pulse wave amplitude decrease index > 23.5 (median) showing 50.8% risk reduction (HR 0.508, 95%CI 0.291–0.885). The combination of low pulse wave amplitude decrease index (≤ 23.5) and high apnea–hypopnea index synergistically increased major adverse cardiovascular events risk by 116% (HR 2.161, 95%CI 1.049–4.454, P < 0.001) versus double-negative group. Low pulse wave amplitude decrease index correlated with older age, higher Low-density lipoprotein, and elevated cardiovascular risk (all P < 0.05), suggesting endothelial dysfunction and autonomic dysregulation as mechanisms. The pulse wave amplitude decrease index independently predicts cardiovascular risk in obstructive sleep apnea and can be automatically measured via standard pulse oximetry, offering a practical tool for identifying high-risk patients needing intensive treatment.