°Institute of Cardiovascular Disease, University of Medicine, “Aldo Moro”, Bari, Italy
Corresponding Author: Pierluigi Carratù, Division of Internal Medicine, Clinica Medica “A. Murri”, Department of Biomedical Sciences and Human Oncology, University of Bari ‘”Aldo Moro”, Bari, Italy. Piazza G. Cesare 12, 70122, Bari, Italy.
e-mail:pierluigi.carratu@uniba.it/ Fax number 080 5592907.
Abstract
Background Obstructive Sleep Apnea (OSA) is a worldwide increasing syndrome, which, by promoting endothelial dysfunction, contributes to extend the cardiovascular risk. We evaluated the cardiovascular risk in a group of OSA patients.
Methods A total of 185 OSA subjects (19 normal weight, 57 overweight, 109 obeses), seen at the Ambulatory of Sleep Disorders, during one year, entered the study. We assessed anthropometric features, polysomnographic findings, cardiovascular risk factors, smoking habit, Pulmonary Function Test, Arterial Blood Gas Analysis, Epworth Questionnaire, and Charlson Co-morbidities Index (CCI). Subjects were divided into three groups, according to their BMI: individuals with BMI ≥30 Kg/m2 (Group 1 n=109, mean age 61 ± 1; 74.3 % males), individuals with BMI ranging from 25.0 to 29.9 Kg/m2 defined as overweight subjects (Group 2 n=57, mean age 58.8 ± 1.4; 77% males) and subjects with a BMI ranging from 18.5 to 24.9 Kg/m2 defined normal weight subjects (Group 3 n=19, mean age 54.2 ± 2.3; 64,2% males).
Results In the whole population, the percentage cardiovascular risk was weakly related with BMI (r=0.33; P<0.001), but not with AHI. The cardiovascular risk was strictly related to the obesity (p<0.00002), while the Epworth Questionnaire score and the Charlson Co-morbidity Index were respectively statistically higher in the group of obese individuals (p=0.006, p=0.00002) than in the other 2 Groups. When AHI values were stratified in tertiles, the percentage cardiovascular risk did not vary with increasing AHI values (Figure 2).
Conclusions Further studies are required to investigate the pivotal role of inflammation due to obesity, and underlying increased cardiovascular risk in OSA patients.
Keywords: Obstructive Sleep Apnea, Obesity, BMI, Cardiovascular Risk, Polysomnography, Continuous Positive Airway Pressure.
Introduction
The cardiovascular risk is defined by WHO/ISH by risk prediction charts, which indicate 10-year risk of a fatal or nonfatal major cardiovascular event (myocardial infarction or stroke), according to age, sex, blood pressure, smoking status, total and HDL blood cholesterol, presence or absence of diabetes mellitus, and anti-hypertensive treatment (1)
Obstructive Sleep Apnea (OSA) is a worldwide increasing syndrome and is a persistent long term risk factor for several cardio-pulmonary diseases (2). In particular, in patients with OSA, chronic upper airways inflammation constantly promotes a systemic endothelial dysfunction (3,4) worsens the cardio-pulmonary activity, thus, affecting the left and the right heart performance (5) increases risk of cardiovascular events, over time (6).
Obesity plays a well established pivotal role in the evolution of the cardiovascular risk in patients with OSA (7). Indeed, in obese individuals, the eccentric ventricular hypertrophy and the diastolic heart failure are responsible for developing cardio-myopathy, a well-recognized complication in severe obese patients (8). The augmented left ventricular filling pressure, transmitted into the pulmonary venous system, improves pulmonary venous pressures leading to increased pulmonary vascular resistance (9). Obesity is also linked with elevated serum hs-CRP levels in patients with sleep-disordered breathing (10), further contributing to chronic systemic inflammation. Thus, the complex interplays among OSA, insulin resistance, hypercholesterolemia, obesity, chronic systemic inflammation and elevated left ventricular filling is responsible for endothelial dysfunction, with Pulmonary Hypertension (PH) and finally increasing cardiovascular risk in affected subjects (11,12,13). However, besides the combined role of these factors, it is still under debate if the severity of OSA can act per se, as an independent factor in determining the extent of the cardiovascular risk in obese patients (14).
In the present study, we depicted the cardiovascular risk of a consecutive population of OSA patients enrolled at the Sleep Ambulatory, and studied for anthropometric features, cardiovascular risk, and Polysomnographic findings.
Subjects and Methods