Association of obstructive sleep apnoea with subclinical coronary atherosclerosis

Abstract

Background

Accumulating evidence suggests a role of obstructive sleep apnoea (OSA) as a risk factor for coronary atherosclerosis. This study aimed i) to assess the prevalence of OSA in the general population and ii) to analyse the association of this disorder with traditional cardiovascular disease risk factors and subclinical coronary atherosclerosis.

Methods

In a cross-sectional analysis of the Heinz Nixdorf Recall study a subgroup of 1604 subjects (791 men, age 50–80 years) underwent OSA screening. Furthermore, coronary artery calcium (CAC) was measured. OSA was defined as apnoea-hypopnoea index (AHI) ≥ 15/h.

Results

OSA was observed in 29.1% of men and 15.6% of women. In a multiple linear regression analysis adjusted for risk factors AHI was associated with CAC in men aged ≤65 years (estimated log-transformed increase of CAC = 0.25, 95% confidence interval (CI) = −0.001–0.50, p = 0.051) and in women of any age (estimated log-transformed increase = 0.23, 95% CI = 0.04–0.41, p = 0.02). Doubling of the AHI was associated with a 19% increase of CAC in men aged ≤65 years and with a 17% increase in women of any age.

Conclusions

In the general population aged ≥50 years OSA is associated with subclinical atherosclerosis in men aged ≤65 years and in women of any age, independent of traditional cardiovascular risk factors.

Introduction

Sleep-disordered breathing (SDB) describes a group of disorders characterized by irregularities of respiration during sleep. The most common SDB is obstructive sleep apnoea (OSA), characterized by recurrent narrowing or closing of the upper airway due to the sleep related reduction of muscle tone. The reported prevalence of OSA ranges from 7 to 25% in men and from 2 to 11% in women [1], [2], [3]. Compared with the general population, OSA is more frequent in cohorts with hypertension (30–83%) [4], [5], diabetes (23–58%) [6], [7], heart failure (12–53%) [8], [9], ischaemic heart disease (30–58%) [10], [11], and stroke (44–63%) [12], [13]. Severe untreated OSA is associated with fatal and non-fatal cardiovascular events in comparison to healthy controls [14], [15]. In the Sleep Heart Health Study, an association of OSA with incident coronary artery disease (CAD) independent of traditional cardiovascular disease (CVD) risk factors was observed in men <70 years, but not in women [16].

Coronary artery calcium (CAC) is a non-invasive measure of subclinical coronary atherosclerosis and a strong predictor of coronary and CVD events beyond established risk stratification algorithms [17], [18]. As both OSA and CAC predict CVD events, OSA and CAC may be associated even in early stages of CAD. To date, four studies have investigated this association [19], [20], [21], [22]. OSA was found to be associated with subclinical coronary atherosclerosis quantified by CAC in a cohort of 202 middle-aged patients with suspected sleep disorders [19]. In a community sample of 224 participants a higher apnoea-hypopnoea index (AHI) was associated with a measurable CAC of any degree, relative to no CAC [20]. In a cross-sectional community-based study among 258 middle-aged men, OSA and obesity were positively associated with the presence and extent of CAC, but only obesity and not OSA remained a significant independent contributor after adjustment for potential cardiovascular risk factors [21]. In a population of 97 patients with suspected OSA it was observed that only age and not AHI was independently associated with CAC [22].

To date, large-scale studies in population-based cohorts analysing associations between OSA and CAC are missing and sex-specific differences are not investigated yet. Therefore, we studied the prevalence of OSA in a general population aged 50–80 years and analysed the association of the AHI with traditional cardiovascular risk factors and subclinical coronary atherosclerosis as defined by the CAC score in both sexes.