The impact of obesity on cardiac dysfunction in patients with sleep-disordered breathing

Longitudinal effect of nocturnal R-R intervals changes on cardiovascular outcome in a community-based cohort

RATIONALE

Sleep-disordered breathing (SDB) is strongly linked to adverse cardiovascular outcomes (cardiovascular diseases (CVD)). Whether heart rate changes measured by nocturnal R-R interval (RRI) dips (RRI dip index (RRDI)) adversely affect the CVD outcomes is unknown.

OBJECTIVES

To test whether nocturnal RRDI predicts CVD incidence and mortality in the Wisconsin Sleep Cohort study (WSCS), independent of the known effects of SDB on beat-to-beat variability.

METHODS

The study analysed electrocardiograph obtained from polysomnography study to assess the nocturnal total RRDI (the number of RRI dips divided by the total recording time) and sleep RRDI (the number of RRI dips divided by total sleep time). A composite CVD risk as a function of total and sleep RRDI was estimated by Cox proportional hazards in the WSCS.

RESULTS

The study sample consisted of 569 participants from the WSCS with no prior CVD at baseline were followed up for up to 15 years. Nocturnal total RRDI (10-unit change) was associated with composite CVD event(s) (HR, 1.24 per 10-unit increment in RRDI (95% CI 1.10 to 1.39), p<0.001). After adjusting for demographic factors (age 58±8 years old; 53% male; and body mass index 31±7 kg/m²), and apnoea-hypopnoea index (AHI 4%), individuals with highest total nocturnal RRDI category (≥28 vs<15 dips/hour) had a significant HR for increased incidence of CVD and mortality of 7.4(95% CI 1.97 to 27.7), p=0.003). Sleep RRDI was significantly associated with new-onset CVD event(s) (HR, 1.21 per 10-unit increment in RRDI (95% CI 1.09 to 1.35), p<0.001) which remained significant after adjusting for demographic factors, AHI 4%, hypoxemia and other comorbidities.

CONCLUSION

Increased nocturnal RRDI predicts cardiovascular mortality and morbidity, independent of the known effects of SDB on beat-to-beat variability. The frequency of RRDI is higher in men than in women, and is significantly associated with new-onset CVD event(s) in men but not in women.

Increased ultrasensitive C-reactive protein is not associated with obesity in hospitalized heart failure patients

Objective:

To evaluate the association between obesity and levels of high-sensitivity C-reactive protein (hs-CRP) in patients with heart failure admitted to a tertiary hospital.

Methods:

Cross-sectional study with a consecutive sampling of hospitalized patients with heart failure. Sociodemographic and clinical data were collected, and the nutritional status was assessed through indicators such as body mass index (in kg/m²), waist circumference (in cm), waist-hip ratio, triceps skinfold (in mm) and subscapularis skinfold (in mm). Neck circumference (in cm) was measured as well as serum levels of hs-CRP, in mg/L.

Results:

Among 123 patients, the mean age was 61.9±12.3 years and 60.2% were male. The median of hs-CRP was 8.87mg/L (3.34 to 20.01). A tendency to an inverse correlation between neck circumference and hs-CRP was detected (r=-0.167; p=0.069). In the multiple linear regression analysis, after adjustment for age, disease severity (NYHA classification III and IV, low ejection fraction, left ventricular dysfunction during diastole), and infectious conditions there was an inverse association between hs-CRP and neck circumference (ß=-0.196; p=0.03) and subscapularis skinfold (ß=-0.005; p=0.01) in the total sample, which was not maintained after the stratification by sex.

Conclusion:

Increased levels of hs-CRP in patients hospitalized for heart failure were not associated with obesity.

Predictors of sleep disorders among patients with type 2 diabetes mellitus

AIMS

This study examined the prevalence of sleep disorders (SD) and self-reported sleep symptoms and risk factors among adult patients diagnosed with T2DM.

METHODS

Data were obtained from the 2012 US National Health and Wellness Survey, an annual Internet-based survey. A total of 7239 participants reported a diagnosis of T2DM. Patients also provided information on diagnosis of SD (e.g., insomnia, sleep breathing disorder, other sleep conditions, etc.) and regularly experienced sleep symptoms (e.g., difficulty falling asleep, sleep apnea, daytime sleepiness, difficulty staying awake, etc.). Logistic regressions were used to examine factors associated with SD and symptoms.

RESULTS

The average age was 59.9 (standard deviation=12.2), 59.5% were male, 24.4% were diagnosed with SD, 76.8% reported experiencing any sleep symptom regularly (difficulty falling asleep, 30.5%; sleep apnea, 17.4%; daytime sleepiness, 26.8%; difficulty staying awake, 10.1%). Logistic regression models showed the strongest predictors of diagnosed SD were obesity class (OC) III (OR=2.20), White (OR=1.92), OC II (OR=1.57), smoking (OR=1.57), lower income (OR=1.49-1.19), unemployment (OR=1.38), and comorbidities (OR=1.35), all p<0.05. The strongest predictors of any sleep symptom were OC III (OR=2.22), OC II (OR=1.78), lower income (OR=1.74-1.24), female gender (OR=1.72), OC I (OR=1.60), White (OR=1.54), and smoking (OR=1.47), all p<0.05.

CONCLUSIONS

Almost 25% of patients with T2DM were diagnosed with SD and over 75% reported experiencing at least one sleep symptom regularly. SD and symptoms were strongly associated with obesity, White ethnicity, gender, low income, and smoking. Interventions focusing on weight management and smoking cessation have shown to improve T2DM and may improve SD.