Relationship between sleep apnoea and mortality in patients with ischaemic heart failure.

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 < or =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 > or =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.