Association of Nocturnal Hypoxemia With Lower Cardiovascular Events in Patients With Acute Coronary Syndrome and OSA

The relationship between OSA-related nocturnal hypoxemia and cardiovascular outcomes in patients with acute coronary syndrome (ACS) remains controversial.

Is the severity of nocturnal hypoxemia associated with cardiovascular outcomes in patients with ACS with and without OSA?

We conducted a retrospective analysis of pooled data from 2 prospective cohort studies including 2,810 patients with ACS. Patients were stratified by percentage of time with arterial oxygen saturation < 90% (TSA90) into 3 tertiles: mild, moderate, and severe nocturnal hypoxemia. The primary end point was 1-year major adverse cardiovascular and cerebrovascular events (MACCEs). Cox proportional hazards models were used for multivariable analysis.

Among 2,810 patients with ACS, 1,408 patients had OSA and 1,402 patients did not have OSA. In patients with OSA, those with moderate and severe hypoxemia demonstrated lower MACCE rates compared with those with mild hypoxemia (77.8 and 72.7 per 1,000 person-years, respectively, vs 120.0 per 1,000 person-years; P = .044). After multivariable adjustment, severe hypoxemia was associated with 50% lower risk of MACCE (hazard ratio [HR], 0.50; 95% CI, 0.29-0.87; P = .015) and 68% lower risk of nonfatal myocardial infarction (HR, 0.32; 95% CI, 0.12-0.86; P = .023). Moderate hypoxemia showed 79% lower all-cause mortality (HR, 0.21; 95% CI, 0.05-0.84; P = .028) and 84% lower cardiovascular death (HR, 0.16; 95% CI, 0.03-0.78; P = .024). Restricted cubic spline analysis revealed U-shaped relationships between TSA90 and outcomes in patients with OSA. Patients without OSA showed no significant associations across hypoxemia tertiles (P > .05 for all).

Our results indicate that in patients with ACS and OSA, moderate to severe nocturnal hypoxemia is associated with reduced cardiovascular events. These findings warrant further investigation into OSA management strategies in patients with ACS.