Introduction:
Diastolic heart failure, or heart failure with preserved ejection fraction (HFpEF) accounts for approximately 50% of all heart failure and it is associated with increased morbidity and mortality similar to systolic heart failure (1). It has been suggested that DD is the result of a response to systemic inflammation predisposed by multiple comorbidities such as obesity, hypertension, and diabetes that may lead to remodeling of the myocardium, signaling dysfunction and finally cardiomyocyte hypertrophy, myocardial stiffness and progressive interstitial fibrosis (2). Noteworthy, DD has been found to be an independent predictor of mortality in patients with normal left ventricular ejection fraction (1). Therefore, the early detection of susceptible persons and the identification of new risk factors for DD and HFpEF and attempting to control such conditions is crucial for the management of these patients.
Although observational data suggest a bidirectional relationship between obstructive sleep apnea (OSA) and HFpEF (3), it remains unknown whether this association is due to OSA itself or is mediated by the higher burden of co-existing cardio-metabolic disorders frequently seen in OSA patients.
OSA is a chronic respiratory sleep disorder characterized by repetitive apnea/hypopnea episodes induced by narrowing of the upper airway during sleep. The intermittent episodes of hypoxemia and sympathetic overdrive shown to be associated with these apneas and hypopneas lead to endothelial dysfunction, systemic inflammation, oxidative stress, arterial hypertension exerting deleterious effects in the cardiovascular system. OSA has been associated with increased risk for coronary artery disease, heart failure, arrhythmias, and pulmonary hypertension (4).
Although previous studies have suggested an association between OSA and DD, the majority of them were limited by the retrospective nature, small sample size, and the high prevalence of clinical confounders including hypertension, obesity, and diabetes that these patients exhibit. Therefore, in this meta-analysis we sought to investigate the correlation between DD and OSA in patients free of conventional cardiovascular risk factors.