Depression is a risk factor for mortality after myocardial infarction: fact or artifact?

This study sought to investigate the long-term impact of depression on cardiac mortality after myocardial infarction (MI) and to assess whether the timing of depression influences the findings.

Previous studies have shown that depression increases the risk of cardiac death after MI, although some studies with robust methodology have failed to show this effect. Clinical trials of depression treatments have failed to improve mortality. Until the relationship between depression and post-MI mortality is understood fully, clinical trials aimed at reducing mortality by treating depression remain premature.

We recruited 588 subjects after MI and followed up their cases for up to 8 years. Patients underwent detailed assessments of cardiac status, conventional cardiac risk factors, and noncardiac illness at baseline. Depression was assessed for the period immediately preceding MI and at 12 months after MI, using a standardized questionnaire and a research interview. At follow-up, the mortality status, cause, and date of death were recorded for 587 subjects using population records.

Multivariate predictors of cardiac death included older age (hazard ratio [HR] = 1.04, p = 0.007), previous angina (HR = 1.8, p = 0.03), previous MIs (HR = 1.6, p = 0.004), Killip class (HR = 1.8, p = 0.005), beta-blockers (HR = 0.5, p = 0.023), and angiotensin-converting enzyme inhibitors (HR = 0.6, p = 0.047) prescribed on discharge. Depression was not associated with cardiac mortality, whether detected immediately before MI (p = 0.48), 12 months after MI (p = 0.27), or at both time points (p = 0.97).

The association between depression and post-MI mortality is complex, possibly being limited to depression immediately after MI. Defining the window when intervention for depression might benefit survival is crucial for the design of future trials.