Background: Obstructive sleep apnea (OSA) may predispose patients to congestive heart failure (CHF), suggesting a deleterious effect of OSA on myocardial contractility.
Methods: A cross-sectional study of 85 subjects with suspected OSA who had undergone their first overnight polysomnogram, accompanied by an echocardiographic study. Patients were divided according to the apnea-hypopnea index as follows: < 5 (control subjects); 5 to 14 (mild OSA); and >or= 15 (moderate-to-severe OSA). Right and left ventricular function was evaluated using the myocardial performance index (MPI) and other echocardiographic parameters. For the right ventricle analyses, we excluded patients with a Doppler pulmonary systolic pressure of >or= 45 mm Hg, while for the left ventricle we excluded patients with an ejection fraction of <or= 45%.
Results: The mean (+/- SD) age was 60 +/- 15 years, and 83% were men. Right and left ventricular function were altered in patients with OSA, especially in those with the moderate-to-severe OSA, even after adjustment for potential confounders. The mean right MPI was 0.23 +/- 0.10 in control subjects, 0.26 +/- 0.16 in patients with mild OSA, and 0.37 +/- 0.11 in patients with moderate-to-severe OSA (p value for trend, < 0.01). The mean left MPI values were 0.28 +/- 0.05, 0.27 +/- 0.07, and 0.41 +/- 0.14, respectively (p value for trend, 0.04). Right and left MPI correlated positively and significantly with the apnea-hypopnea index (rho = 0.40, p = 0.002; and rho = 0.27, p = 0.02, respectively). Mean left atrial volume index was increased in patients with OSA (control subjects, 26.8 +/- 11; patients with mild OSA, 32.5 +/- 15; and patients with moderate-to-severe OSA, 30.4 +/- 11; p value for trend, 0.04).
Conclusions: OSA, particularly when moderate to severe, is associated with impaired right and left ventricular function and increased left atrial volume. These findings support the notion that OSA may contribute to the development of atrial fibrillation and CHF.