Sleep apnea doubles risk of stroke, death - study - Yahoo! News: "In fact, in the early part of the study, people breathing through CPAP machines seemed to fare worse.
Bradley told Reuters that heart failure patients are given the machines to drive water out of the lungs and reduce the work of breathing. They also may help the heart beat more effectively.
Although using the machines during the 5-1/2-year study did not help patients live longer, they did improve the efficiency of the heart and let patients exercise more."