Because oxygen decreases sympathetic activity and eliminates desaturation, long-term therapy has the potential to decrease the morbidity and mortality of subjects with CHF. Careful, randomized, placebo-controlled, multicenter studies with mortality as the end point require large numbers of patients, are labor-intensive, and are expensive,34yet they need to be conducted. In this context, I am pleased to see the progress of the Canadian study35 to determine the effect of nasal CPAP on the natural history of systolic heart failure. Compared with oxygen, CPAP has the additional advantage of increasing the intrathoracic pressure and decreasing the transmural pressure of the intrathoracic structures. On the other hand, oxygen may have the advantage of improved long-term compliance, although this is an assumption. Furthermore, although afterload reduction is important, it has a small effect on survival in systolic heart failure. In the Studies of Left Ventricular Dysfunction study,34 the overall mortality rate of the placebo arm was 39.7% compared to 35.2% with enalapril (absolute risk reduction, 4.5%). In contrast, therapy with β-blockers increases survival considerably.36 This improved survival, however, in part might have been due to an improvement in sleep-related breathing disorders. Because of various cardiorespiratory effects, such as increasing ejection fraction, decreasing pulmonary capillary pressure, and sympathetic activity, therapy with β-blockers may improve CSA. However, with continued myocyte loss and fibrosis, as left ventricular function deteriorates, sleep-related breathing should recur.