We know that untreated obstructive sleep apnea (OSA) results in nighttime intermittent hypoxia. This occurs when no air is getting in the lungs and no oxygen into the bloodstream due to obstructions at the opening to the upper airway.
A byproduct of the intermittent hypoxia, current research shows is the development of cardiovascular disease which can result in heart attack and sudden cardiac death.
What if there is a mechanism in the body that protects the heart from infarction and ischemic results by increasing the number of blood vessels providing more oxygen in patients with some level of OSA. That is, the body "grows" more blood vessels called coronary collateral vessels (CCV) to serve the heart when it needs more oxygen.
An intriguing study published in the March 2010 issue of Chest puts forward this theory. The publication includes a letter to the editor by Drs. Peretz and Lena Lavie referencing other published work & work they did that supports the hypothesis of this original research.
Interestingly, the benefit seems to accrue to older people with mild to moderate OSA. Perhaps, because it takes time to develop the CCVs and that if the OSA is too severe, the cardiovascular insult is too great to withstand early death.
The study has a small sample (190 subjects) and the authors themselves indicate a number of limitations.
The concluding sentence of the study - In summary, there is an association between sleep apnea and collateral vessel growth. We speculate that OSA(S) may be a significant factor affecting growth of CCVs as a compensatory mechanism.
Not something you can take to the bank, but an interesting hypothesis and tantalizing enough that I will continue to watch with great interest.