Background: Sleep disordered breathing (SDB) is common in severe chronic heart failure (CHF) and is associated with increased morbidity and mortality. The prevalence of SDB in mild symptomatic CHF is unknown.
Aim: The aim of this study was to determine the prevalence and characteristics of SDB in male patients with NYHA class II symptoms of CHF.
Methods and results: 55 male patients with mild symptomatic CHF underwent assessment of quality of life, echocardiography, cardiopulmonary exercise, chemoreflex testing and polysomnography. 53% of the patients had SDB. 38% had central sleep apnoea (CSA) and 15% had obstructive sleep apnoea. SDB patients had steeper VE/VCO(2) slope [median (inter-quartile range) 31.1 (28-37) vs. 28.1 (27-30) respectively; p=0.04], enhanced chemoreflexes to carbon dioxide during wakefulness [mean+/-sd: 2.4+/-1.6 vs. 1.5+/-0.7 %VE Max/mmHg CO(2) respectively; p=0.03], and significantly higher levels of brain natriuretic peptide and endothelin-1 compared to patients without SDB. No differences in left ventricular ejection fraction, percent predicted peak oxygen uptake, or symptoms of SDB were observed.
Conclusions: A high prevalence of SDB was found in men with mild symptomatic CHF. Patients with SDB could not be differentiated by symptoms or by routine cardiac assessment making clinical diagnosis of SDB in CHF difficult.