Influence of Apnea Hypopnea Index and the Degree of Airflow Limitation on Endothelial Function in Patients Undergoing Diagnostic Coronary Angiography

SIMPLE SUMMARY: Obstructive sleep apnea and airflow limitation disorders are linked to increased cardiovascular morbidity and mortality in patients with chronic coronary syndrome. Although the exact mechanism associated with this phenomenon remains poorly elucidated, the impairment of endothelial function observed in both breathing disorders and cardiovascular disease is one of the possible pathophysiological processes linking those conditions. In the present study, we sought to determine the possible relationship between the endothelial function, signs of disturbed respiration during sleep, and airflow limitation in chronic coronary syndrome patients undergoing diagnostic invasive coronary angiography. Our study showed that obstructive sleep apnea signs measured by WatchPAT (respiratory disturbance index, apnea and hypopnea index, and oxygen desaturation index) were associated with endothelial dysfunction. Additionally, greater airflow limitation by spirometry was detected in patients with endothelial dysfunction. Patients with endothelial dysfunction showed an increase in left ventricular hypertrophy with a trend of increase in left atrial enlargement, indicating underlying diastolic dysfunction. However, the endothelial dysfunction was independent of the presence or severity of obstructive coronary artery disease in coronary angiography. We believe that our study may complement and extend the current understanding of endothelial dysfunction in the mechanism, explaining the relationship between sleep apnea and cardiovascular diseases. ABSTRACT: Background: Obstructive sleep apnea is associated with an increased prevalence of cardiovascular disease. The mechanism of these associations is not completely understood. We aimed to investigate the association of the apnea hypopnea index and the degree of airflow limitation with endothelial dysfunction. Methods: This was a single-center prospective study of patients admitted for diagnostic coronary angiography (CAG). Endothelial function was assessed by the non-invasive EndoPAT system by reactive hyperemia index (RHI) and divided into two groups: endothelial dysfunction and normal endothelial function. Sleep apnea signs were detected by WatchPAT measuring the respiratory disturbance index (pRDI), the apnea and hypopnea index (pAHI), and the oxygen desaturation index (ODI). Patients underwent spirometry and body plethysmography. Based on CAG, the severity of coronary artery disease was assessed as follows: no significant coronary artery disease, single-, two- and three-vessel disease. Results: A total of 113 patients were included in the study. Breathing disorders measured by WatchPAT and spirometry were more severe in patients with endothelial dysfunction: pRDI (27.3 vs. 14.8, p = 0.001), pAHI (24.6 vs. 10.3, p < 0.001), ODI (13.7 vs. 5.2, p = 0.002), forced expiratory volume in one second (FEV(1)) (81.2 vs. 89, p = 0.05). In a multivariate regression analysis, pAHI and FEV(1) were independent predictors of endothelial dysfunction assessed by RHI. There was no correlation between the severity of coronary artery disease and endothelial dysfunction. Conclusions: Obstructive sleep apnea signs and greater airflow limitation were associated with endothelial dysfunction regardless of the severity of the coronary artery disease.