Integrated area of desaturation, a new index of sleep-disordered breathing, is associated with left ventricular hypertrophy among hypertensive men with obstructive sleep apnea

Abstract

Purpose: It is recognized that obstructive sleep apnea (OSA) plays an independent role in the pathogenesis of arterial hypertension. Left ventricular (LV) hypertrophy, especially concentric hypertrophy, is also well-known as an important prognostic predictor for cardiovascular events in patients with hypertension. We, therefore, assessed the relationship between LV hypertrophy and OSA severity among hypertensives using a new index, integrated area of desaturation (IAD), considering both duration and degree of hypoxia for analysis of polysomnography. Methods: This study comprised 227 hypertensive men under the age of 65 with OSA, who were free of cardiovascular diseases and had normal LV ejection fraction. They had overnight fully attended polysomnography with suspicion of sleep apnea in addition to echocardiography and laboratory check on the next morning. LV geometry was obtained in accordance with relationship between LV mass index and relative wall thickness ratio. Results: They had fairly good control of blood pressure (134.6+/-15.3/82.4+/-10.4 mmHg) and apnea-hypopnea index (AHI) of 44.9+/-27.1/hr. There was a weak but significant correlation between LV mass index (133.0+/-22.8 g/m 2) and IAD index (r=0.20, p<0.01). Patients with concentric hypertrophy had higher IAD index than those with normal geometry (132.2+/-167.8 vs. 91.7+/-116.5). A multivariate regression analysis showed that IAD, B-type natriuretic peptide and age - but not body mass index, blood pressure, low-density lipoprotein, HbA1c, hsCRP, plasma renin activity and plasma aldosterone concentration - were independent variables for detecting LV mass index (beta=0.26, 0.24, 0.17, P<0.05, respectively). The IAD index was the only predictor among indices of sleep-disordered breathing such as AHI, oxygen desaturation index 3% and ratio of desaturation below 90%. Conclusions: Nocturnal intermittent hypoxia assessed by IAD may contribute to the development of LV hypertrophy in well-controlled hypertensive male patients.