Ischemia-modified albumin and cardiovascular risk in obstructive sleep apnea and acute coronary syndrome. Long term follow-up after treatment from the ISAACC study

Abstract

Introduction: In the context of the prevailing interest in biomarkers that can assess cardiovascular (CV) risk in obstructive sleep apnea (OSA), ischemia-modified albumin (IMA) is proposed as a potential risk predictor.

Objectives: To evaluate whether IMA levels predict recurrent CV events in patients with acute coronary syndrome (ACS) and OSA, and whether continuous positive airway pressure (CPAP) treatment modifies this risk.

Methods: This post hoc analysis is based on data from the ISAACC study, including 1.011 non-sleepy patients with an ACS. During hospitalization for ACS, a sleep study was conducted and blood samples for IMA determination were obtained. Patients were categorized by their apnea-hypopnea index (AHI) in non-OSA (AHI <15 events/h) or OSA group (AHI ≥15 events/h). "Low" or "high" IMA levels were established based on the median value (⩽ 34.1 U/L or > 34.1 U/L, respectively). The OSA group was randomized to either CPAP or usual care. The recurrence of CV events was evaluated over a 36-months follow-up.

Results: Adjusted cox regression models showed that the OSA group with high IMA level had a significantly reduced risk for CV event recurrence compared with the non-OSA group (HR [95 % CI] 0.59 [0.38-0.93], p = 0.024). In the OSA group with high IMA level, CPAP treatment did not significantly reduce CV recurrence.

Conclusions: OSA was associated with higher IMA levels in patients with ACS. Interestingly, patients with both OSA and high IMA experienced fewer CVEs during follow-up. CPAP treatment demonstrated a non-significant risk reduction in patients with low IMA, whereas no effect was noted in those with high IMA.

Keywords: Acute coronary syndrome; Biomarkers; Cardiovascular risk; Ischemia modified albumin; Ischemic preconditioning; Obstructive sleep apnea.