Objective: To determine whether sleep apnea (SA) influences risk of death differently in patients with ischemic than in those with non-ischemic heart failure (HF).
Design: Prospective observational study.
Patients: Consecutive HF patients with left ventricular ejection fraction ≤45% newly referred to the HF clinic of our institute between September 1, 1997 and December 1, 2004.
Main outcome measures: Patients underwent sleep studies and were divided into those with moderate to severe SA (apnea-hypopnea index ≥15/hr of sleep) and those with mild to no SA (apnea-hypopnea index <15/hr of sleep). They were followed for a mean duration of 32 months to determine all-cause mortality rate.
Results: Of 193 patients, 34 (18%) died. In the ischemic group, mortality risk adjusted for confounding factors was significantly higher in those with SA than those without it (18.9 vs. 4.6 deaths/100 patient-years, HR 3.03, 95%CI 1.04-8.84, P=0.043). In contrast, in the non-ischemic 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=0.987).
Conclusions: In patients with HF, the presence of SA is independently associated with an increased risk of death in those with ischemic, but not in those with non-ischemic etiology. These findings suggest that patients with ischemic cardiomyopathy are more susceptible to the adverse hemodynamic, autonomic and inflammatory consequences of SA than is those with non-ischemic cardiomyopathy.
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