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.