Depression is common following acute coronary syndrome, and thus, it is important to provide knowledge to improve prevention and detection of depression in this patient group. The objectives of this study were to examine: (1) whether indicators of stressors and coping resources were risk factors for developing depression early and later after an acute coronary syndrome and (2) whether prior depression modified these associations.

The study was a register-based cohort study, which includes 87,118 patients with a first time diagnosis of acute coronary syndrome during the period 2001–2009 in Denmark. Cox regression models were used to analyse hazard ratios (HRs) for depression.

1.5 and 9.5 % develop early (≤30 days) and later (31 days–2 years) depression after the acute coronary syndrome. Among all patients with depression, 69.2 % had first onset depression, while 30.8 % developed a recurrent depression. Most patient characteristics (demographic factors, socioeconomic status, psychosocial factors, health-related behavioural factors, somatic comorbidities, and severity of acute coronary syndrome) were significantly associated with increased HRs for both early and later depressions. Prior depression modified most of these associations in such a way that the association was attenuated in patients with a prior depression.

Our results indicate that first time and recurrent depression following acute coronary syndrome have different risk profiles. This is important knowledge that may be used to focus future interventions for prevention and detection.