AbstractBackgroundObstructive sleep apnea (OSA) and metabolic syndrome (MetS) are each increasingly common in patients with acute coronary syndrome (ACS). Whether OSA increases cardiovascular consequences in ACS patients with MetS has not been investigated.HypothesisOSA increases cardiovascular risk in ACS patients with MetS. We aimed to examine the association between OSA and cardiovascular consequences in ACS patients with MetS.MethodsIn this prospective cohort study, we consecutive recruited 2160 ACS patients who underwent portable sleep breathing monitoring. OSA is defined as an apnea‐hypopnea index (AHI) ≥ 15 events/h. The primary endpoint was major adverse cardiovascular and cerebrovascular events (MACCE), including cardiovascular death, myocardial infarction, stroke, ischemia‐driven revascularization, or hospitalization for unstable angina or heart failure.ResultsA total of 1927 patients with ACS were enrolled. Among them, 1486 (77.1%) had MetS and 1014 (52.6%) had OSA. During 2.9 years of follow‐up, the cumulative incidence of MACCE was similar between OSA and non‐OSA groups in patients with MetS (21.9% vs. 17.9%, adjusted hazard ratio [HR] = 1.29 95% confidence interval [CI]: 0.99–1.67,p= .06) and patients without MetS (24.4% vs. 17.3%, adjusted HR = 1.21 95% CI: 0.73–2.03,p= .46). Patients with MetS and OSA had a significantly higher risk of MACCE than patients with MetS and without OSA in women (27.8% vs. 18.1%, adjusted HR = 1.70, 95% CI: 1.01–3.09,p= .04) but not in men (21.0% vs. 17.9%, adjusted HR = 1.19, 95% CI: 0.91–1.59,p= .21).ConclusionsIn hospitalized ACS patients with MetS, comorbid OSA was associated with increased risk of cardiovascular consequences among women.