Timing is everything: the onset of depression and acute coronary syndrome outcome

Conflicting findings have emerged from studies examining the impact of depression on death and readmission following a coronary event, possibly reflecting differences in the measurement of "depression" and the onset of depression in relation to the coronary event. The aim of this study was to examine the relationship between the timing of the depressive episode and 1-year cardiovascular outcome in recruited patients with acute coronary syndrome (ACS).

Patients hospitalized with ACS (N = 489) were recruited and assessed for lifetime and current depression by the Composite International Diagnostic Interview (CIDI) depression schedule. Patients were reinterviewed at 1 and 12 months by telephone to assess depression status and cardiovascular outcomes (ACS readmission and cardiac mortality). Mortality registers were also checked.

Cardiovascular outcome was not associated with the presence of lifetime depression before the ACS admission or with existing depression at the time of the ACS admission. In contrast, depression that developed in the month after the ACS event showed a strong relationship with subsequent cardiovascular outcome, even after controlling for traditional cardiac risk factors. Outcome over the 12 months was more strongly predicted by the timing of depression onset than whether the depression was a first-ever (incident) or recurrent episode.

Only a depressive episode that commenced following an ACS admission was associated with a poorer cardiovascular outcome. If confirmed, this finding would narrow the list of causal mechanisms previously proposed to account for the relationship between depression and coronary events.