Apnea-Hypopnea Index an indicator of increased right cardiac preassures

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Obstructive sleep apnea (OSA) is a disorder frequently associated with clinical conditions and complications such as refractory hypertension, atrial fibrillation, nocturnal angina, dysrhythmias, congestive heart failure and stroke. Polysomnography is the gold standard test required to diagnose OSA, along with a targeted history and comprehensive examination of the patient. It involves the recording of various physiologic variables during sleep. Sleep related obstructive events may be measured using two indices: the apnea-hypopnea index (AHI) and the respiratory disturbance index, an AHI≥15 being diagnostic for OSA. The aim of this study was to determine the interaction between sleep apnea and demographic or echocardiographic markers. Material and methods This was a prospective study that included 33 patients with sleep apnea. Polysomnography was performed using a VitalNight cardiorespiratory polygraph to determine the apnea hypopnea index (AHI) and echocardiography was performed using a Vivid E95 scanner to determine the left ventricular ejection fraction (LVEF), the peak systolic right ventricular to right atrial pressure gradient (Gmax) and the right ventricular diameter and function (TAPSE and s’). Results The mean age of the patients was of 63±8 years and 14 patients (42%) had a Gmax>25mmHg. Regarding cardiovascular risk factors, 31 patients (94%) had arterial hypertension and 26 (79%) were smokers. Out of all patients, 25 (76%) had an appropriate echocardiographic acoustic window. The patients had mean values of AHI of 45±19. Mean values for the LVEF, Gmax, TAPSE and s’ were 53 ± 11%, 25± 14 m/s, 22 ± 4 mm, and 14 ± 3 cm/s, respectively. AHI showed moderate correlations to age (r=0.27), cervical perimeter (r=0.38) and BMI (r=0.30), but also to echocardiographic parameters as LVEF (r=0.29), Gmax (r=0.42), RV diameter (r=0.39), TAPSE (r=0.38) and s’ (r=0.34). ROC curves were determined to calculate the value of AHI to predict a Gmax >25 mmHg. A significant Gmax, as an indicator for increased right cardiac pressures, was predicted with a high sensitivity (86%) and specificity (84%) by a value of AHI > 45 (AUC=0.81, 95%CI = 0.64-0.927, p<0.001). Conclusion In conclusion the study demonstrated that smoking and hypertension are important risk factors in patients with sleep apnea syndrome. There was a significant correlation between AHI and echocardiographic parameters of the right heart. AHI can be used as a predictor of increased right cardiac preassure when the value is above 45.