Issue: November 2015
September 10, 2015
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In CABG patients, flat preoperative diurnal cortisol slope predicts poor outcomes

Issue: November 2015
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In patients undergoing coronary revascularization, a flatter preoperative diurnal cortisol slope appears to be associated with poorer long-term outcomes, according to recent findings.

In the study, Amy Ronaldson, a PhD student at University College London, and colleagues evaluated 250 patients aged 44 to 90 years who underwent elective coronary artery bypass graft (CABG) or CABG plus valve replacement as part of the Adjustment and Recovery After Cardiac Surgery (ARCS) Study to determine the association between rates of adverse cardiac events and death with less variation in presurgical diurnal cortisol levels.

CABG surgery was performed in a single center and included both on-pump and off-pump procedures. Before surgery, patients were given a saliva collection kit and were instructed to collect samples at home and to keep a cortisol diary. Cortisol diaries documented factors likely to cause variation in cortisol samples, including mood, exercise and daily stressors. Seven saliva samples were submitted by each participant over the course of a day, at various time points. Samples were collected an average of 30.6 days prior to surgery.

The study’s long-term clinical outcomes were occurrence of a major adverse cardiac event and all-cause mortality, and these were collected up to 2.68 years postoperatively. The researchers used Cox proportional hazard models to evaluate associations between preoperative cortisol and clinical outcomes. The models included the following covariates: EuroScore, burden of chronic illness and whether the patient had undergone cardiopulmonary bypass.

The researchers found that in the years following surgery, nine patients (3.6%) experienced major adverse CV events, and 10 patients (4%) died; one patient experienced both of these outcomes. There was no significant association between cortisol slope, cortisol area under the curve (AUC) and waking cortisol levels and EuroSCORE, cardiopulmonary bypass or burden of chronic illness. A correlation was noted between evening cortisol levels and EuroSCORE (P = .30) but no association was seen between evening cortisol and cardiopulmonary bypass status or chronic illness burden.

The occurrence of major adverse CV events or mortality following surgery was linked to EuroSCORE (P < .001) and chronic illness burden (P = .003). Presurgical diurnal cortisol slope was predictive of death or major adverse CV event following CABG surgery (HR = 0.73; 95% CI, 0.56-0.96; P = .023). Those with a steeper decline in cortisol over the course of a day had decreased risk for experiencing adverse outcomes. For every nmol/L per hour increase in cortisol slope, the risk for death or major adverse CV event decreased by 27%. Burden of chronic illness (P = .035) and EuroSCORE (P = .002) were also predictive of death or major adverse CV event after surgery.

According to the researchers, these findings suggest that preoperative measures of cortisol slope may be useful in screening patients undergoing CABG.

“Diurnal cortisol profiles can be obtained without difficulty, since the measures are noninvasive and samples are stable for several days,” the researchers wrote. “Measuring diurnal cortisol rhythm may help to identify patients at risk of adverse events or death, allowing additional support and care to be provided.” – by Jennifer Byrne

Disclosure: The researchers report no relevant disclosures.