The effect of obstructive sleep apnoea on timing of acute coronary syndrome

Abstract Background and objective Acute coronary syndrome (ACS) remains the principal cause of death in Malaysia. It is estimated about 20% of ACS occurs at nighttime during sleep between 12am to 6am. Factors associated with nocturnal ACS are unknown. Acute nocturnal pathophysiological response to obstructive sleep apnea (OSA) may increase risk of nocturnal ACS. We hypothesized that OSA risk is associated with timing of ACS onset. Methodology This study included 200 patients with ACS who underwent coronary angiogram for which the time of chest pain onset was clearly identified and divided into 2 groups; nocturnal ACS (12am-5.59am) and non-nocturnal ACS (6am–11.59pm). Two validated questionnaires, STOP-BANG and Epworth Sleepiness Scale (ESS) were self-administered by subjects to determine OSA risk. All subjects timing of ACS onset, OSA risk, demography, anthropometric measurements, comorbidities and echocardiographic characteristics were analyzed. Results Acute coronary syndrome occurs nocturnally in 19% of ACS patients. The prevalence of high risk OSA individuals among ACS patients is 43%. There is significantly higher prevalence of high risk OSA individuals in nocturnal ACS group of 95% compared to 30% of high risk OSA individuals in non-nocturnal ACS group (p=0.001). Nocturnal ACS patients was significantly younger (50.1±8.7yrs, p=0.001), had higher BMI (33.9±4.3kg/m2, p=0.005), waist circumference (106.7±10.3cm, p=0.003) and larger neck circumference (44.6±3.3cm, p=0.001) compared to non-nocturnal ACS group. These groups had similar prevalence of other comorbidities for ACS and showed no significant difference between left and right ventricular systolic function. In multiple logistic regression analysis, the most significant predictors for nocturnal ACS are OSA risk, neck circumference and age. Conclusion There is a strong association between high risk OSA individuals and nocturnal ACS onset. Patient with nocturnal ACS onset should be screened for OSA and prioritized for polysomnography. OSA prevalence according to ACS onset Funding Acknowledgement Type of funding source: None