Objective: To determine whether the influence of sleep apnoea (SA) on the risk of death differs in patients with ischaemic and in those with non-ischaemic heart failure (HF).
Design: Prospective observational study.
Patients: Consecutive patients with HF with left ventricular ejection fraction ⩽45% newly referred to the HF clinic between 1 September 1997 and 1 December 2004.
Main outcome measures: Patients underwent sleep studies and were divided into those with moderate to severe SA (apnoea–hypopnoea index ⩾15/h of sleep) and those with mild to no SA (apnoea–hypopnoea index <15/h of sleep). They were followed up for a mean of 32 months to determine all-cause mortality rate.
Results: Of 193 patients, 34 (18%) died. In the ischaemic group, mortality risk adjusted for confounding factors was significantly higher in those with SA than in those without it (18.9 vs 4.6 deaths/100 patient-years, hazards ratio (HR) = 3.03, 95% CI 1.04 to 8.84, p = 0.043). In contrast, in the non-ischaemic HF group, there was no difference in adjusted mortality risk between those with, and those without, SA (3.9 vs 4.0 deaths/100 patient-years, p = 0.929).
Conclusions: In patients with HF, the presence of SA is independently associated with an increased risk of death in those with ischaemic, but not in those with non-ischaemic, aetiology. These findings suggest that patients with ischaemic cardiomyopathy are more susceptible to the adverse haemodynamic, autonomic and inflammatory consequences of SA than are those with non-ischaemic cardiomyopathy.
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Funding: Supported by a programme grant PRG-5275 from the Heart and Stroke Foundation of Ontario. DY is supported by an unrestricted research fellowship from Respironics Inc, JSF by a Canada Research Chair in integrative cardiovascular biology and a Career Investigator Award from the Heart and Stroke Foundation of Ontario, HW was supported by research fellowships from the departments of medicine of the University of Toronto and Merck-Frosst, SM by a New Investigator Award from the Heart and Stroke Foundation of Ontario, PR by a research fellowship from Siriraj Hospital, Mahidol University, Bangkok, Thailand and JDP by a Career Investigator Award from the Heart and Stroke Foundation of Ontario.
Competing interests: None.
Ethics approval: Ethics committee approval from Mount Sinai Hospital and Toronto Rehabilitation Institute.