Right ventricular dysfunction in patients with obstructive sleep apnoea syndrome

There is conclusive evidence that obstructive sleep apnoea syndrome (OSAS) influences right heart haemodynamics and can also induce pulmonary hypertension. It is not known, however, whether right ventricular dysfunction can occur in patients with OSAS in the absence of lung disease. We studied 107 patients (94 males, 13 females, mean age 55 +/- 11 yrs) with polysomnographically verified OSAS in whom clinically significant lung disease was excluded. Right ventricular ejection fraction (RVEF) was determined by radionuclide ventriculography. In addition, pulmonary function tests, arterial blood gas analysis and right heart catheterization were performed. RVEF was impaired in 19 patients (18%). Eighteen (95%) had signs or symptoms consistent with mild right ventricular failure. Patients with or without impaired RVEF did not differ with respect to body mass index, age or lung function. Stepwise multiple logistic regression analysis revealed that RVEF was significantly associated with the apnoea/hypopnoea index (r = -0.68; p = 0.0009) and the extent of nocturnal oxyhaemoglobin saturation (r = 0.42; p = 0.035), but not with age, body mass index, blood gas analysis, gender, lung function, pulmonary artery pressure and left ventricular ejection fraction. We conclude that in patients with otherwise unexplained right ventricular failure, obstructive sleep apnoea syndrome may underlie the right ventricular dysfunction.