Profile of sleep disordered breathing in heart failure with preserved ejection fraction

Heart failure (HF) with preserved ejection fraction (HFpEF) represents nearly half of HF cases and is increasingly being recognized as a cause of morbidity and mortality. Hypertension (essential or secondary) is an important risk factor of HFpEF, owing to permanent structural changes in heart. A common cause of secondary hypertension is obstructive sleep apnea (OSA). In the present study, we have attempted to seek the frequency and characteristics of sleep disordered breathing (SDB) in HFpEF. Also, we tried to investigate if any correlation exists between the severity of SDB and the severity of diastolic dysfunction. This was a prospective, cross-sectional, case-control study in which 25 case patients with HFpEF and 25 control subjects were included. All the case patients and control subjects went through a detailed clinical, biochemical, echocardiography evaluation and overnight polysomnography. SDB was seen in 64% of the case patients having HFpEF and in 12% of control group with [odds ratio (OR)= 12.2, 95% confidence interval (CI) = 2.83-52.74; p<0.001]. A significant correlation of apnea-hypopnea index (AHI) severity was observed with degree of diastolic dysfunction (r = 0.67; p<0.001). Among HFpEF patients with SDB (16/25), 13 had OSA and only 3 had central sleep apnea (CSA). CSA was present in patients with severe diastolic dysfunction. There were no clinical or sleep quality differences among the OSA and the CSA group. To conclude, a higher frequency of SDB is observed in HFpEF patients. AHI severity correlates with degree of diastolic dysfunction. The underlying mechanisms of correlation between SDB and diastolic dysfunction either through uncontrolled hypertension or direct causation warrant further evaluation.