Background The Canadian Continuous Positive Airway Pressure for Patients with Central Sleep Apnea and Heart Failure trial tested the hypothesis that continuous positive airway pressure (CPAP) would improve the survival rate without heart transplantation of patients who have central sleep apnea and heart failure.
Methods After medical therapy was optimized, 258 patients who had heart failure (mean age [±SD], 63±10 years; ejection fraction, 24.5±7.7 percent) and central sleep apnea (number of episodes of apnea and hypopnea per hour of sleep, 40±16) were randomly assigned to receive CPAP (128 patients) or no CPAP (130 patients) and were followed for a mean of two years. During follow-up, sleep studies were conducted and measurements of the ejection fraction, exercise capacity, quality of life, and neurohormones were obtained.
Results Three months after undergoing randomization, the CPAP group, as compared with the control group, had greater reductions in the frequency of episodes of apnea and hypopnea (–21±16 vs. –2±18 per hour, P<0.001) and in norepinephrine levels (–1.03±1.84 vs. 0.02±0.99 nmol per liter, P=0.009), and greater increases in the mean nocturnal oxygen saturation (1.6±2.8 percent vs. 0.4±2.5 percent, P<0.001), ejection fraction (2.2±5.4 percent vs. 0.4±5.3 percent, P=0.02), and the distance walked in six minutes (20.0±55 vs. –0.8±64.8 m, P=0.016). There were no differences between the control group and the CPAP group in the number of hospitalizations, quality of life, or atrial natriuretic peptide levels. An early divergence in survival rates without heart transplantation favored the control group, but after 18 months the divergence favored the CPAP group, yet the overall event rates (death and heart transplantation) did not differ (32 vs. 32 events, respectively; P=0.54).
Conclusions Although CPAP attenuated central sleep apnea, improved nocturnal oxygenation, increased the ejection fraction, lowered norepinephrine levels, and increased the distance walked in six minutes, it did not affect survival. Our data do not support the use of CPAP to extend life in patients who have central sleep apnea and heart failure.