PRedictOrs, PHEnotypes and Timing of Obstructive Sleep Apnea in Acute Coronary Syndrome

Obstructive Sleep Apnea (OSA) is a well-known disorder of upper airways collapse during sleep time leading to oxygen desaturation and sleep fragmentation. Despite being increasingly recognized as cardiovascular risk, the effect of OSA on clinical outcomes after Acute Coronary Syndrome (ACS) is not fully defined. Also, OSA syndrome is highly prevalent in ACS and may be related to the deterioration of cardiac function resulting in worsening of the severity of sleep apnea or the intermittent hypoxia could be cardio-protective via the ischemic preconditioning event. Serial sleep studies have shown the progressive reduction of the Apnea / Hypopnea Index (AHI) from the admission in Coronary Care Unit (CCU) to 6 weeks, 12 weeks and 6-month follow up, making necessary to re-assess the severity of OSA after discharge. Therefore, further research in this field is necessary to screen and predict those ACS patients who may experience a change in their AHI index over time.

Obstructive Sleep Apnea (OSA) is a well-known disorder of upper airways collapse during sleep time leading to oxygen desaturation, sleep fragmentation, tissue suffering and hypercapnia. The repeated airways collapse leads to a fall of blood saturation levels during sleep time and it is linked to daytime sleepiness, road traffic accidents, cognitive deficits, depression, myocardial infarction, pulmonary hypertension and stroke.

Despite being increasingly recognized as a major cardiovascular risk, the effect of OSA on clinical outcomes after Coronary Artery Disease (CAD) is not fully defined. The presentation of Acute Coronary Syndrome (ACS) can be unstable angina, non-ST Elevation Myocardial Infarction (NSTEMI) or ST-Elevation Myocardial Infarction (STEMI). Sleep apnea prevalence in the context of acute coronary syndromes (ACS) is sizeable, varying from 36.9%-82% when polysomnography is executed briefly after admission in Cardiovascular Care Unit (CCU). The high prevalence of OSA in ACS may be related to the deterioration of cardiac function resulting in worsening of the severity of sleep apnea. In converse, OSA has also been proposed as a protective factor in CAD. The intermittent hypoxia related to OSA could have a cardio-protective role during acute ACS via the phenomenon of "ischemic preconditioning", showing that in acute MI patients higher AHI was associated with lower peak troponin-T levels in partially and fully adjusted models.

Furthermore, the improvement of cardiac outcomes at the follow-up post-discharge seems to positively influence the severity of OSA. In particular, serial sleep studies have interestingly shown a progressive reduction of the AHI at 6 weeks, 12 weeks and 6-month follow up, making necessary to re-assess the severity of OSA after discharge. Therefore, further research in this field is necessary to screen and predict those ACS patients with a diagnosis of OSA made at admission in CCU who may experience a change in their AHI index over time, in order to identify those with a potential unfavourable prognosis.

Eligibility Criteria:
Inclusion Criteria:

* Subjects with a diagnosis of ACS (STEMI or NSTEMI) admitted to CCU of our institution within 72 hours from Myocardial Infarct (MI)
* Age between 18 and 85 years old

Exclusion Criteria:

* Previous diagnosis of OSA or ongoing CPAP treatment
* Chronic/Home Oxygen therapy
* Cardiogenic shock
* Heart failure exacerbation
* use of mechanical ventilation
* Active use of benzodiazepines
* Pregnancy or breastfeeding
* Unable to sign the informed consent