Is Obstructive Sleep Apnea more Prevalent than Central Sleep Apnea in Patients with Systolic Heart Failure? A Retrospective Study

Central sleep apnea (CSA) rather than obstructive sleep apnea (OSA) is widely believed to be the dominant form of sleep apnea (SA) in patients with heart failure (HF). Hitherto, no study has characterized sleep disordered breathing (SDB) in Indian subjects with heart failure and evaluated its impact on severity of HF, which this study attempts to do. A retrospective data-analysis was done in 65 consecutive patients with stable mild-to-moderate HF referred for evaluation on the basis of fatigue and excessive daytime somnolence (EDS) regarded by the institute’s cardiologists. Patients with ejection fraction (EF) 30). HF was arbitrarily classified as mild (EF:<35%) moderate (EF:35-45%) and severe (EF:45-55%). OSA emerged as the exclusive form of SA (95.4%; n=65) and was more severe in males. Patients with more severe HF tended to be less obese, and interestingly to have less severe OSA. In contrast to Western literature, OSA seems to be by far the most prevalent form of sleep apnea in Indian subjects with HF. HF mortality is known to be high in underweight individuals yet, persons with severe HF are often less obese and partly by reason of a lower BMI, appear to be relatively protected against severe OSA and severe nocturnal hypoxemia. This study thus raises important and intriguing questions which merit further enquiry.