Depressive symptoms after acute myocardial infarction (AMI) are related with adverse health outcomes. However, the risk factors and course of depressive symptoms after AMI have not been widely investigated, especially in Asian populations. We aimed to evaluate changes in the prevalence of depressive symptoms and the associated risk factors at 3 mo after AMI. We also investigated the associations among functional capacity, physical activity (PA), and depressive symptoms.

This cross-sectional study was conducted for 1545 patients who were admitted for AMI and referred to cardiac rehabilitation (CR) between August 2015 and March 2019. Of these patients, 626 patients completed the Patient Health Questionnaire-9 (PHQ-9), the Korean Activity Scale Index (KASI), and the International Physical Activity Questionnaire (IPAQ) 3 mo following AMI. A PHQ-9 score of ≥5 was considered to indicate depressive symptoms.

The prevalence of depressive symptoms was 30% at baseline and decreased to 12% at 3 mo after AMI. Depressive symptoms were significantly associated with low functional capacity (OR = 2.20, P = .004) and unemployment status (OR = 1.82, P = .023). After adjusting for variables including functional capacity, depressive symptoms exhibited a significant relationship with low PA after AMI (OR = 1.80, P = .023).

Systematic screening and treatment for depressive symptoms and efforts to promote CR may help to improve PA and functional capacity in Korean patients with AMI. Such efforts may aid in reducing the depressive symptoms and related adverse outcomes.