Abstract 3480: Day-night Variation Of Acute Myocardial Infarction In Obstructive Sleep Apnea
BACKGROUND: Obstructive sleep apnea (OSA) is a prevalent condition characterized by acute nocturnal hemodynamic and neurohormonal abnormalities that may increase the risk of acute myocardial infarction (AMI) during the night, a time when the occurrence of AMI in the general population is the lowest.
METHODS: We prospectively studied 61 patients admitted to our hospital with AMI, for which the time of onset of chest pain was clearly identified. The presence or absence of OSA was determined by overnight polysomnography. For patients with and without OSA we compared the frequency of AMI during different intervals of the day based on the onset time of chest pain.
RESULTS: The diurnal variation in the onset of AMI in patients with OSA and without OSA is showed in fig 1⇓. AMI occurred from midnight to 6 a.m. in 32% of patients with OSA and 5% of patients without OSA (P=0.02). The odds ratio of having an AMI between midnight and 6 a.m. was 8.8 times greater (95% C.I. 1–73.2) for patients with OSA when compared to those without OSA (p =0.02). Conversely, the odds ratio of having an AMI between 6 a.m. and noon was 4.8 times greater (95% C.I 1.4 –16.4) for patients without OSA than for patients with OSA (P=0.01). Of all patients having an AMI between midnight and 6 a.m., 93% had OSA (p=0.001).
CONCLUSIONS: The diurnal variation in the onset of AMI in patients with OSA is strikingly different from the diurnal variation in patients without OSA. The onset of AMI in OSA patients is the highest during sleep hours, a time when the onset of AMI is the lowest in patients without OSA. These findings suggest that OSA may be a trigger for AMI. Patients having nocturnal onset of AMI should be evaluated for OSA.