CPAP No Good For Secondary Prevention of Cardiac Events and Stroke 

But it does seem to help with snoring, daytime sleepiness, and quality of life.

From MedPageToday:

“Treating obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) did not reduce risk of recurrent coronary or cerebrovascular events, the randomized SAVE trial showed.

For people with coronary or cerebrovascular disease, treatment of moderate-to-severe OSA showed no advantage over usual care for the composite of cardiovascular death, myocardial infarction (MI), stroke, or hospitalization for unstable angina, heart failure, or transient ischemic attack.”

Source: ESC: CPAP Flops for Secondary CV Prevention | Medpage Today