Obstructive sleep apnea and cardiovascular risk: is metabolic syndrome the link?

Obstructive sleep apnea risk and subclinical atherosclerosis in South Asians living in the United States

OBJECTIVES

The objective of this study was to examine the association between high risk of obstructive sleep apnea (OSA) and subclinical atherosclerosis among South Asians in the United States.

DESIGN

A secondary analysis of cross-sectional data.

SETTING/PARTICIPANTS

A community-based cohort of 906 men and women participating in the Mediators of Atherosclerosis in South Asians Living in America (MASALA) study.

MEASUREMENTS

The Berlin Questionnaire was used to screen for OSA risk. Coronary artery calcium (CAC), common carotid artery intima-media thickness (IMT), and internal carotid artery IMT were used as measures of subclinical atherosclerosis.

RESULTS

The majority of participants (59%) with high OSA risk had CAC scores >0 compared with only 41% of participants with low OSA risk (P <.001). The high OSA risk group was older (P =.005), male (P =.04), had higher body mass index (P <.001) and had greater common carotid artery IMT (0.96 ± 0.27 mm) and internal carotid artery IMT (1.33 ± 0.42 mm) measurements. Snoring, sleep-disordered breathing (SDB), and high OSA risk were associated with subclinical atherosclerosis. However, only high OSA risk remained significant in multivariable models after controlling for demographic and clinical factors that included hypertension (HTN), obesity, diabetes, and dyslipidemia.

CONCLUSIONS

High OSA risk, which includes overlapping comorbidities of HTN and obesity, was not associated with the time living in the US but was associated with subclinical atherosclerosis markers. These cardiovascular disease risk factors should include evaluation of the spectrum of SDB among all adults, including South Asian men and women.

Insulin Sensitivity and Insulin Resistance in Non-Diabetic Middle-Aged Patients with Obstructive Sleep Apnoea Syndrome

Background:

Obstructive sleep apnoea syndrome (OSAS) has been linked with abnormal glucose metabolism, insulin resistance (IR) and development of diabetes mellitus.

Methods:

Non-diabetic patients (n=69) with OSAS, diagnosed by polysomnography, were prospectively recruited. To evaluate IR among OSAS patients, the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) and Insulin sensitivity by Quantitative Insulin sensitivity Check Index (QUICKI) were used.

Results:

HOMA-IR was positively associated with body-mass index (BMI) (ρ=0.364, p=0.002), time with oxyhaemoglobin saturation <90% (ρ=0.291, p=0.015), arousal index (ρ=0.268, p=0.027), Epworth sleepiness scale (ESS) score (ρ=0.293, p=0.019) and negatively with average oxyhaemoglobin saturation (ρ=-0.398, p=0.001) and minimum oxyhaemoglobin saturation (ρ=-0.327, p=0.006). QUICKI was positively associated with forced vital capacity (r=0.301, p=0.014), average oxyhaemoglobin saturation (r=0.443, p<0.001), minimum oxyhaemoglobin saturation (ρ=0.318, p=0.008), and negatively associated with sleep stage transitions (r=-0.266, p=0.032), oxygen desaturation index (r=-0.404, p=0.005), time with oxyhaemoglobin saturation <90% (r=-0.311, p=0.019), arousal index (r=-0.344, p=0.004) and ESS score (r=-0.299, p=0.016). After adjustment for age and BMI, HOMA-IR was associated with sleep stage transitions, time with oxyhaemoglobin saturation <90%, average oxyhaemoglobin saturation, minimum oxyhaemoglobin saturation and arousal index. QUICKI was associated with oxygen desaturation index, sleep stage transitions, ESS score, minimum oxyhaemoglobin saturation and arousal index.

Conclusions:

An independent association between OSAS and IR in patients without pre-existing diabetes mellitus was observed. Recurrent hypoxia and sleep fragmentation in OSAS are associated with IR in these patients.

[Arterial hypertension and sleep apnea hypopnea syndrome in primary care]

INTRODUCTION AND OBJECTIVES

Sleep apnea hypopnea syndrome (SAHS) is frequent in hypertensive patients and plays a role in a greater incidence of cardiovascular morbidity-mortality. This study aims to know the clinical profile of hypertensive patients with SAHS compared to hypertensive patients without SAHS to know which variables should be used to orient their screening from primary care.

METHODOLOGY

An observational, descriptive, retrospective study of cases (hypertensive patients with SAHS) and controls (hypertensive patients without) was performed in an urban health care center. Based on a computerized registry of the site, patients diagnosed of SAHS and hypertension over 30 years of age were selected. For each case, one control case of hypertensive patients without SAHS paired by age and gender was randomly obtained.

RESULTS

A total of 64 cases and 64 controls were selected. Standing out in the bivariate analysis were greater BMI (34.3±12.8 vs. 28.6±3.6), predominance of obesity (70.3 vs. 35.9%), metabolic syndrome (77.3 vs. 42.2%), consumption of psychopharmaceuticals (19.7 vs. 7.8%) and anithypertensive drugs (26.5 vs. 14.0%), ischemic heart disease (20.3 vs. 9.4%) in the case group versus control group (P<.05 for all the variables). The multivariate analysis showed that only the presence of metabolic syndrome was related with the presence of SAHS in hypertensive patients (OR 4.65; 95% CI: 2.03-10.64; P<.001).

CONCLUSIONS

Screening for SAHS should be performed in hypertensive patients seen in primary care if they have metabolic syndrome criteria.

Renal Denervation

Resistant hypertension, defined as failure to reach blood pressure (BP) goals despite treatment with ≥3 antihypertensive agents, one of which is a diuretic, bears a significant risk of cardiovascular complications. Strong evidence exists, implicating the overactivation of the sympathetic nervous system (SNS) in the pathogenesis of resistant hypertension through complex neurohormonal interactions. Renal denervation is a novel attractive option to achieve adequate blockade of the sympathetic system, with subsequent BP reductions in patients with resistant hypertension. Data have shown promising results regarding the efficacy of the procedure, maintaining a favorable safety profile. As such, the paradigm of resistant hypertension has expanded in other conditions involving a hyperadrenergic state such as the metabolic syndrome, heart failure, arrhythmias, sleep apnea, and renal failure. This review focuses on the pathophysiological rationale of modifying SNS tone and the evidence of the benefits of such intervention beyond BP control.

Is there evidence of early vascular disease in patients with obstructive sleep apnoea without known comorbidities? Preliminary findings

We evaluated early atherosclerotic lesions in 20 non-smokers with newly diagnosed Obstructive Sleep Apnoea (OSA) and without known comorbidities by measuring common carotid artery intima media thickness (CCA-IMT), transcranial Doppler ultrasound (TCD), and ankle brachial index (ABI). These were compared with 20 healthy age- and BMI-matched controls. In OSA patients, CCA-IMT was not significantly higher vs. controls (0.74±0.17 vs. 0.66±0.12 mm, p=0.201) and it was positively correlated with neck circumference (r=0.466, p=0.039), arousal index (r=0.663, p=0.001), gamma-glutamyl transpeptidase activity (r=0.474, p=0.035) while it was negatively correlated with Forced Expiratory Volume in 1 sec (r=-0.055, p=0.012). No difference was noted between patients and controls in terms of vascular stenosis on TCD examination, while asymptomatic peripheral artery disease was found in one patient with OSA. In conclusion, OSA patients without known comorbidities exhibit a non-significant increase in CCA-IMT without further evidence of vascular disease, but additional experience in a larger patient series is needed.

Predictors of Blood Pressure Reduction With Nocturnal Continuous Positive Airway Pressure Therapy in Patients With Obstructive Sleep Apnea and Prehypertension

Previous studies showed that treatment of obstructive sleep apnea syndrome (OSAS) with continuous positive airway pressure (CPAP) significantly reduced the blood pressure (BP) in hypertensive patients. We investigated the predictors of BP change in normotensive patients with OSAS who underwent CPAP. A total of 24 patients with OSAS (19 male; age: 48.7 ± 10.4 years) were enrolled. The 24-hour mean BP (24 hMBP), subjective sleepiness, fasting venous blood samples, and anthropometric measurements were assessed at baseline, 6th week and 12th week of CPAP treatment. The 24 hMBP fell at 12 weeks from 89.2 ± 8.4 to 82.9 ± 7.3 mm Hg ( P < .0001) irrespective of the severity of disease. Also, both daytime and nighttime BP showed significant reduction after CPAP. Male gender, Epworth sleepiness scale, body mass index, smoking, alcohol use, and baseline 24 hMPB were the independent predictors of a fall in 24 hMBP. The CPAP therapy may provide benefit even in the absence of overt hypertension by reducing both daytime and nighttime BP.

Impact of chronic obstructive pulmonary diseases on outcomes and hospital days after percutaneous coronary intervention

Chronic obstructive pulmonary disease (COPD) is common in patients undergoing percutaneous coronary intervention (PCI), but the impact of COPD on outcomes after PCI has received limited attention. Consecutive patients with coronary heart disease (n = 5155) undergoing PCI were enrolled in this study; 645 patients (73% men) aged 68.4 ± 13.2 years had COPD and 4510 patients (71% men) aged 64.7 ± 12.1 years did not. During the in-hospital period after PCI, the patients with COPD experienced a significantly higher incidence of angina (P < .001), arrhythmias (P < .001), and composite major adverse cardiac events (MACEs; P < .001) and longer hospital stay (P < .001) than those without COPD. Additionally, severity of COPD (measured by pulmonary function tests) was associated with increased composite MACE (P < .001) and hospital stay (P < .001) after PCI. In conclusion, COPD is associated with significantly increased composite MACE and hospital stay in patients after PCI. Increasing severity of COPD is associated with increased composite MACE and hospital stay after PCI.