Your doctor says that you need to wear that Darth Vader mask, which caps off a bad month. First, that little bit of shortness of breath you were having when walking fast turned out to be coronary artery disease. That led to the placement of stents in the blood vessels in your heart. In addition to new medications, you were then referred to a cardiac rehabilitation program where instruction was provided on exercising more, losing weight, and changing to a healthier diet. The last straw is that because of a history of snoring, a sleep study was done and showed obstructive sleep apnea, a condition where you stop breathing at night. Your doctor recommended treatment with continuous positive airway pressure (CPAP) to reduce the risk that your coronary heart disease will progress to a heart attack or stroke.
But, is there evidence to support this recommendation?
The best treatment for moderate to severe obstructive sleep apnea is CPAP. It is a device worn while asleep that works like a reverse vacuum cleaner and applies pressure through a mask into the airway to keep it from collapsing during breathing. Obstructive sleep apnea is a risk factor for the development of high blood pressure, coronary artery disease, stroke, and premature death. Treatment with CPAP lowers blood pressure, and there is some evidence that it may prevent the development of heart disease and eliminate the risk of early death. Until recently, however, evidence that CPAP is beneficial in those who already have heart disease was not available. Now, the results of a large international clinical trial indicate that CPAP may not reduce the risk of heart disease progression.
The SAVE trial recruited 2,717 adults with coronary artery disease or history of stroke from seven countries (though not the United States). Half were treated with CPAP and half were not. After an average follow-up of 3.7 years, the number of people who died from heart disease, had a heart attack, had a stroke, or were hospitalized for heart failure was the same — for both the people using CPAP and those who didn’t.
Does this mean that you should not use CPAP if you have heart disease and sleep apnea? Not at all. Despite its lack of benefit in reducing heart disease and stroke in this study, people in the CPAP group had an improvement in daytime sleepiness, depression and anxiety symptoms, and overall quality of life. Furthermore, there was a suggestion that stroke risk was lower in the CPAP group. In addition, it is important to note that most of the subjects were Asian, and that the risk factors for obstructive sleep apnea are different in Asians than in other ethnic groups.
Finally, only 42% of the subjects in the CPAP group used it for more than four hours per night, which is the minimum amount of time considered as acceptable use in the United States. It is possible that any benefit of CPAP in preventing progression of heart disease will require greater usage. Although one could use the results of this study as an excuse to not use CPAP, until there is further information it would be a mistake to do so. The study reaffirms that CPAP reduces sleepiness and improves quality of life. More studies will be necessary to conclude that it does not reduce risk of progression in those who already have heart disease.