Depressive symptom dimensions and cardiac prognosis following myocardial infarction: results from the ENRICHD clinical trial

Background. Depression following myocardial infarction (MI) independently increases risk for early cardiac morbidity and mortality. Studies suggest that somatic, but not cognitive, depressive symptoms are responsible for the increased risk. However, the effects of somatic depressive symptoms at follow-up, after sufficient time has elapsed to allow for physical recovery from the initial infarction, are not known. Our aim was to examine the relationship between cognitive and somatic depressive symptom dimensions at baseline and 12 months post-MI and subsequent mortality and cardiovascular morbidity. Method. Patients were 2442 depressed and/or socially isolated men and women with acute MI included in the Enhancing Recovery in Coronary Heart Disease (ENRICHD) clinical trial. We used principal components analysis (PCA) of the Beck Depression Inventory (BDI) items to derive subscales measuring cognitive and somatic depressive symptom dimensions, and Cox regression with Bonferroni correction for multiple testing to examine the contribution of these dimensions to all-cause mortality, cardiovascular mortality, and first recurrent non-fatal MI. Results. After adjusting for medical co-morbidity and Bonferroni correction, the somatic depressive symptom dimension assessed proximately following MI did not significantly predict any endpoints. At 12 months post-MI, however, this dimension independently predicted subsequent all-cause [hazard ratio (HR) 1.43, 95% confidence interval (CI) 1.13-1.81] and cardiovascular mortality (HR 1.60, 95% CI 1.17-2.18). No significant associations were found between the cognitive depressive symptom dimension and any endpoints after Bonferroni correction. Conclusions. Somatic symptoms of depression at 12 months post-MI in patients at increased psychosocial risk predicted subsequent mortality. Psychosocial interventions aimed at improving cardiac prognosis may be enhanced by targeting somatic depressive symptoms, with particular attention to somatic symptom severity at 12 months post-MI.