Study objectives: Conflicting results have been reported regarding the effects of obstructive sleep apnea syndrome (OSAS) on daytime left ventricular (LV) systolic function. This study aimed to assess the prevalence and causes of LV systolic dysfunction, using radionuclide angiography, in a large group of patients with OSAS.
Design and setting: A prospective study in the pneumology department of a university medical center.
Patients: One hundred sixty-nine consecutive patients with OSAS diagnosed by polysomnography, hospitalized for the administration of nasal continuous positive airway pressure. Patients with a known cardiac disease were excluded.
Measurements: LV ejection fraction (LVEF) was measured in all patients, using radionuclide ventriculography with multiple-gated equilibrium cardiac imaging. Myocardial scintigraphy with a dipyridamole stress test and echocardiography were performed in those patients with LV systolic dysfunction, defined by a LVEF < 50%, to detect silent heart disease, especially coronary artery disease.
Results: LV systolic dysfunction was observed in 7.7% (13 of 169 patients). In these 13 patients, the mean ± SD LVEF was 42 ± 6%, the lowest value of LVEF was 32%, and no silent cardiac disease was revealed. Age, body mass index, apnea-hypopnea index, parameters of nocturnal oxyhemoglobin desaturation, and prevalence of systemic hypertension did not significantly differ between patients with LVEF < 50% and those with LVEF > 50%. In seven patients with LV dysfunction, LVEF was measured following treatment of OSAS and reached normal values.
Conclusion: OSAS may be a direct cause of daytime LV systolic dysfunction that can resolve following reversal of nocturnal apneas.