Abstract 14320: Determination of the Impact of Short Term Continuous Positive Airway Pressure on Myocardial Energetics in a Randomized Study of Patients with Chronic Stable Heart Failure and Obstructive Sleep Apnea
Background: Obstructive sleep apnea (OSA) often coexists with heart failure (HF) and appears to independently predict death in HF patients (pts). Both are states of increased metabolic demand. Continuous positive airway pressure (CPAP), alleviates OSA and may improve LV function, but it is unclear if this is at the expense of oxidative metabolism. This would represent an unfavorable energetics effect. This study aimed to evaluate the effects of 6 weeks of CPAP on myocardial efficiency in pts with OSA and HF.
Methods/Results: Forty-five pts with OSA (Apnea-Hypopnea Index (AHI) > 10/min) and stable HF with a) LVEF <45%; b) NYHA Class > II-III were enrolled: (mean age 61.4±12.7 yrs; 76% male; LVEF 35.8±9.7%; BSA 2.2±0.2 m2; 42% DM; 64% ischemic etiology of HF; 76% HTN; 16% NYHA class ≥III). Pts were randomized to 6 weeks with CPAP (Group A: N=22) or No-CPAP (Group B: N=23). Characteristics were similar between A vs. B with the exception of BSA (A: 2.3±0.2 m2 vs. B: 2.1±0.2 m2, p=0.003). Pts were evaluated using echocardiography and 11C- acetate PET at baseline and approximately 6 weeks later. Myocardial efficiency was estimated by the work metabolic index (WMI) = [SV index (SVI) x HR x systolic BP/ k-mono] where k-mono is the mono-exponential fit of the myocardial 11C acetate PET time-activity data, reflecting the rate of myocardial oxidative metabolism. CPAP therapy was associated with a non-significant change in WMI compared to No-CPAP (delta 3.1±15.7 vs 0.14±20.4 x10e5 mmHg·mL/m2respectively; p =NS). However, in pts with severe OSA (AHI >20), CPAP led to an increase in WMI (Table; p<0.05) compared to No-CPAP. Increase in SBP (p<0.05) and non-significant changes in SVI occurred without any increase in k-mono.
Conclusions: In pts with HF and severe OSA, 6 weeks of CPAP therapy improved cardiac efficiency indicating an energy sparing effect. This effect on energetics may contribute to beneficial effects of CPAP therapy in this population.
- © 2011 by American Heart Association, Inc.