Symptom burden of sleep-disordered breathing in systolic heart failure patients.

In clinical practice, approximately half of patients with heart failure have preserved left ventricular systolic function, with high morbidity and mortality rates, and major socio-economic burden derived from their management [2]. The majority of patients who present with heart failure and normal systolic function do not have a defined myocardial disease, but it has been demonstrated that they have abnormalities in active relaxation and passive stiffness [3], i.e. they have alterations in the mechanical function during diastole that lead to the development of diastolic heart failure. Diastolic heart failure has differential clinical and pathophysiological features [4, 5]. A close association between sleep-disordered breathing and diastolic heart failure has been previously reported [5, 6]. Only heart failure patients with systolic heart failure were studied by HASTINGS et al. [1]. Therefore, the findings from this study cannot be generalised to the entire population of heart failure patients, particularly with regard to heart failure patients with preserved systolic function, and this should be noted in the title or discussed by the authors throughout the manuscript.