Diurnal Cortisol Rhythm Is Associated With Adverse Cardiac Events and Mortality in Coronary Artery Bypass Patients

PURPOSE There is growing evidence that the hypothalamic-pituitary-adrenal axis plays a role in the progression of cardiovascular disease. We examined the relationship between diurnal cortisol rhythm and adverse events in patients undergoing coronary artery bypass graft (CABG) surgery. We hypothesized that a flatter presurgical diurnal cortisol slope would be associated with higher rates of adverse cardiac events and death in the years following the CABG procedure. METHODS Repeated measures of saliva were taken over the day from 250 CABG patients 1 month before surgery to assess diurnal cortisol slope and overall output (area under the curve). Long-term clinical outcomes were occurrence of a major adverse cardiac event (MACE) and death, and were collected up to 2.68 (SD = 0.40) years after surgery. Cox proportional hazard models were used to determine relationships between presurgical cortisol and clinical outcomes. EuroSCORE, chronic illness burden, and whether or not the patient had undergone cardiopulmonary bypass were included as covariates in the models. RESULTS Diurnal cortisol slope predicted the occurrence of MACE or death after surgery (hazard ratio = 0.73; 95% confidence interval = 0.56-0.96; P = .023). Patients with a steeper slope were at reduced risk of adverse outcomes. This association was driven by changes in both waking and evening cortisol levels. CONCLUSION These results provide evidence for a link between diurnal cortisol rhythm and recovery after CABG. Measuring diurnal cortisol slope before surgery may help to identify those patients at risk of adverse outcomes in the years after the procedure.