Obstructive Sleep Apnea and Acute Myocardial Infarction and the Role of CPAP Treatment: a Double -Blind, Randomized Control Trial

Obstructive sleep apnea (OSA) is a major public health problem affecting at least 2-4% of middle-aged population. OSA resulted in hypoxia and sleep fragmentation, which resulted in neurocognitive dysfunction and cardiovascular sequelaes. The cardiovascular sequelaes in OSA included hypertension, coronary artery disease and heart failure. Our data showed among 599 moderate-sever OSA (AHI<15/hr)， 44.5% patients had cardiovascular disease, which included 41.4% having hypertension，7% having CAD and 2.4% having congestive heart failure。 Though OSA is well known to be highly correlated with fatal and non-fatal cardiac event, only limited studies investigated how OSA affected acute myocardial infarction (AMI). Most studies concluded that AMI would worsen OSA and vice versa. However, how AMI exactly interacts with OSA and what the prevalence of OSA in the first-time AMI is have never been answered. Within four weeks from Nov. 15th 2007, we screened ten patients of first-time AMI with single-vessel disease and Killip I. Five in 10 received PSG and three in five have moderate OSA.

So far, CPAP is the standard treatment for patients with moderate to severe OSA. CPAP could improve airway patency, daytime sleepiness, functional status, blood pressure, metabolic abnormalities and quality of life. In our study, we enrolled 24 non-sleepy OSA and 30 sleepy OSA to study the four-week CPAP effect. The results showed the apnea-hypopnea index, hypoxia, arousal, sleepiness and fatigue could be corrected with CPAP treatment in both groups. However, CPAP could only lower risk factors for cardiovascular disease, like blood pressure, epinephrine, norepinephrine and CRP, in sleepy OSA. Our finding supported that CPAP effect was not similar in the subgroups of severe OSA, so CPAP effect should be studied in every subgroup of OSA patients before it's applied. Till now, there's no literatures reported if CPAP treatment would decrease the morbidity and mortality of AMI.

Sham CPAP mimicked all the characteristics of a true CPAP except for the null pressure, which was recently used as the placebo to study CPAP effect. Therefore, using this optimized placebo, we propose this double-blind, control randomized trial (1) To determine the prevalence of OSA in patients of first-time AMI in acute phase; (2) To determine the impact of CPAP treatment on the prognosis of AMI; (3) Determine how the OSA affects patients with MI in acute and chronic phase and vice versa, which is dissected from mechanical basis and molecular basis.