Sleep-disordered breathing in women was associated with coronary artery disease
ACP J Club. 1997 May-Jun;126:78. doi:10.7326/ACPJC-1997-126-3-078
Mooe T, Rabben T, Wiklund U, Franklin KA, Eriksson P. Sleep-disordered breathing in women: occurrence and association with coronary artery disease. Am J Med. 1996 Sep;101:251-6.
To determine the relation between coronary artery disease and sleep-disordered breathing in women.
Blinded case-control study.
Hospital in Sweden.
118 women who were ≤ 70 years of age and were referred because of stable angina pectoris for consideration of angioplasty or surgical intervention were included. Patients were excluded if technical failures occurred or if they received sedative medication within 12 hours of recordings. Oxygen desaturation and sleep apnea were completely analyzed in 102 (mean age 61 y, range 43 to 70) and 100 women, respectively. Controls were 50 age-matched women selected from the county population registry who had no known heart disease and had not received sedative medication.
Assessment of risk factors
Sleep-disordered breathing (oxygen desaturation and apnea-hypopnea index [defined as the average number of episodes of apnea or hypopnea per hour of sleep], periodic breathing, duration of sleep, and arterial oxygen saturation) assessed during an overnight sleep analysis, age, hypertension, smoking status (current or former), diabetes, body mass index, waist:hip ratio, and left ventricular function.
Main outcome measures
Coronary artery disease verified by coronary angiography.
Patients with angina pectoris had more severely disordered breathing during sleep than did controls. Oxygen desaturation index, apnea-hypopnea index, and percentage of sleep with periodic breathing were higher in patients with angina pectoris than in controls (P < 0.01 for all). After adjustment for age, hypertension, body mass index, smoking habits, and diabetes, multiple logistic regression analysis found that an apnea-hypopnea index ≥ 5 was independently predictive of coronary artery disease (odds ratio [OR] 4.1, 95% CI 1.7 to 9.7, P < 0.01). Smoking (current or former) and hypertension were also independent predictors of coronary artery disease (OR 2.4, CI 1.0 to 5.7, P < 0.05 and OR 3.4, CI 1.3 to 8.9, P < 0.05, respectively). An oxygen desaturation index ≥ 5 and diabetes were not independent predictors of coronary artery disease (P = 0.14 and P = 0.08, respectively).
Sleep-disordered breathing measured as an apnea-hypopnea index ≥ 5 was independently associated with the risk for coronary artery disease in women ≤ 70 years of age.
Sources of funding: Swedish National Association for Heart and Lung Patients; Swedish Heart Lung Foundation; Norrland Heart Fund; Medical Faculty, Umeå University.
For article reprint: Dr. T. Mooe, Department of Internal Medicine, Cardiology Section, Norrland University Hospital, S-901 85 Umeå, Sweden. FAX 46-90-137-633.
The association of sleep-disordered breathing with coronary artery disease is complicated by common associations, such as high body mass index and smoking history. The study by Mooe and colleagues follows a previous study of 142 men with coronary artery disease (1). The associations found for women in the current study closely match those shown for men. Controls in both studies were matched for age but not for weight or smoking status. Nevertheless, the association between coronary artery disease and the apnea-hypopnea index was statistically significant in a multivariate analysis. The relation between sleep-disordered breathing and cardiac disease is complicated by periodic breathing. Such breathing is associated with cardiac failure and can cause daytime tiredness; however, it would not be expected to cause the same vascular problems as do obstructive apneas and hypopneas because obstructed breathing and large intrathoracic pressure changes are not present.
Important questions that arise from this study are whether the sleep apnea could have been suspected clinically and whether it should be treated. Patients in the intervention group reported a trend toward more daytime sleepiness compared with controls. Self-reports of snoring did not differ between groups, and the association between sleepiness and sleep-study findings in these patients is unclear from the report. Continuous positive nasal airway pressure is likely to remove the pathophysiologic link between obstructive sleep and heart disease (2), although adequate prospective studies have not been published. In practice, predisposing factors common to ischemic heart disease and obstructive sleep apnea, such as being overweight or smoking, should be addressed and a high degree of suspicion for sleep-disordered breathing should be maintained for patients with cardiac problems. This means that questions will need to be asked about daytime somnolence, nighttime sleep, and the snoring patterns of patients and their partners. Sleep studies can be done for persons with a high degree of suspicion. The evidence from Mooe and colleagues does not justify routine sleep studies in patients with coronary artery disease.
P. John Rees, MD
Guy's and St. Thomas' Medical and Dental SchoolLondon, England, UK
P. John Rees, MD
Guy's and St. Thomas' Medical and Dental School
London, England, UK