Elderly patients with new-onset acute myocardial infarction (MI) who fit the criteria for obstructive sleep apnea (OSA) were found to be at greater risk for heart rhythm disorders and for major adverse cardiovascular and cerebrovascular events (MACCEs), according to study findings published in Journal of Geriatric Cardiology.
As the most common form of sleep apnea, researchers highlight that OSA has been associated with increased risk of hypertension, heart failure, and mortality for cardiovascular diseases. However, recent studies have indicated that OSA may provide a potential protective effect in cases of MI, “which is attributed to chronic intermittent hypoxia resulting in ischemic preconditioning of the myocardium,” explained the study authors.
Seeking to further examine this potential relationship in the elderly, who exhibit high prevalence of OSA, poor in-hospital prognosis, and recurrence of acute MI (AMI), researchers prospectively enrolled 252 patients with new-onset AMI who were undergoing revascularization. Patients had a mean age of 68.5 (6.9).
Participants completed a sleep study during their hospitalization where they were then split into 2 groups based on the apnea–hypopnea index (AHI); patients in the non-OSA group (n = 130) had an AHI score of less than 15 and those in the OSA group (n = 122) exhibited an AHI score of 15 or greater.
Researchers assessed the association of OSA with heart rhythm disorders and prognosis in patients with new-onset AMI, with the 2 groups being compared for changes in the autonomic nervous system, incidence of arrhythmia during nocturnal sleep, and MACCEs.
“MACCEs were defined as composite events of cardiovascular death, MI, stroke, ischemia-driven revascularization, or hospitalization for unstable angina or heart failure.”
Compared with the non-OSA group, patients with OSA presented with significantly higher body mass index (25.8 [3.6] vs 24.1 [3.1] kg/m2 ) and peak high-sensitivity C-reactive protein levels (52.81 [27.0] vs 23.99 [10.91] mg/L), as well as lower levels of minimum nocturnal oxygen saturation (MinSaO2) (79.7 [8.7%] vs 86.0 [4.5]%).
Patients in the OSA group were found to be at greater risk of multi-vessel coronary artery disease, heart rate variability, and heart rate turbulence onset (all P < .05). Notably, occurrence of atrial arrhythmias was nearly 3-fold higher in those with OSA than those without (44.4% vs 16.7%; P < .05), with a higher incidence of sinus and ventricular arrhythmias also reported.
After a median follow-up of 6 months, patients with OSA and hypoxia (MinSaO2 ≤ 80%) were independently associated with a more than 4 times greater risk of MACCE incidence (HR, 4.536; 95% CI, 1.461-14.084; P = .009), after adjusting for risk factors such as age, sex, BMI, and smoking history.
“OSA-induced hypoxia may correlate with the severity of myocardial infarction, increase the occurrence of heart rhythm disorders in elderly subacute MI patients, and worsen their poor outcomes in the short term,” concluded the study authors.
Wang LJ, Pan LN, Yan RY, Quan WW, Xu ZH. Obstructive sleep apnea increases heart rhythm disorders and worsens subsequent outcomes in elderly patients with subacute myocardial infarction. J Geriatr Cardiol. Published online January 28, 2021. doi:10.11909/j.issn.1671-5411.2021.01.002