After an acute myocardial infarction (MI), patients may develop posttraumatic stress disorder (PTSD). There is evidence for alterations in the hypothalamic-pituitary-adrenal axis in PTSD. An association between patients` cortisol level after experiencing an MI and subsequent PTSD symptoms has not been investigated yet. Therefore, the aim of this study was to examine whether serum cortisol measured in patients admitted to hospital for acute coronary care after MI is predictive of PTSD symptoms at three and 12 months post-MI, respectively.
Patients (N=106) with a verified MI and high risk for the development of MI-induced PTSD symptoms were included in the study within 48 hours of hospital admission for acute coronary intervention. Serum cortisol was measured from fasting venous blood samples the next morning. Hierarchical regression analysis was used to test for an independent contribution of cortisol levels from admission to the Clinician-Administered PTSD Scale sum score three and 12 months after discharge from the coronary care unit.
Hierarchical regression analysis showed that lower serum cortisol levels were significantly associated with more severe PTSD symptoms three months (B=-0.002, p=0.042) and 12 months (B=-0.002, p=0.043) post-MI.
The generalizability of the findings is limited to patients with high acute peri-traumatic distress and without an acute severe depressive episode. The study does not provide any information about the diurnal cortisol pattern.
Lower serum cortisol measured during MI hospitalization may predict more severe MI-induced PTSD symptoms three and 12 months after hospital discharge.

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