Background: Several studies have associated depressive symptoms with an increased risk for cardiac events after the onset of acute myocardial infarction (AMI). The aim of the present study is to investigate the impact of the depressive symptoms on prognosis of the elderly patients with AMI.
Method: Depression was assessed in consecutive patients with AMI (n = 1042; mean age 63 +/- 11 years) using the Zung Self-Rating Depression Scale (SDS). Patient with a score > or = 40 was classified as having depressive symptoms. Cardiac events (cardiac death, nonfatal re-MI, coronary angioplasty or bypass surgery, readmission for heart failure, unstable angina, or uncontrolled arrhythmia) were examined during 12 months follow-up period.
Results: Depressive symptoms were observed in 438 patients (42.0%). Prevalence of depression was not dependent of age (P = 0.60) and gender (P = 0.91). The rate of cardiac events was 31.2% per year in patients with depressive symptoms whereas 23.9% per year in patients without depressive symptoms. Multiple logistic regression analyses showed that depression was significantly associated with 1-year cardiac events (odds ratio 1.41, 95% CI 1.03 to 1.92, P = 0.03) after controlling for age, gender, severity of myocardial infarction, coronary risk factors, e.g. hypertension, diabetes mellitus and smoking habits. Depression was a significant risk factor for the cardiac events (log rank, P = 0.02) in the elderly patients (> or = 65 years old, 501 patients). However, the association of depression with cardiac events in the young patients (< 65 years old, 541 patients) was not statistically significant (P = 0.11).
Conclusion: Depression after AMI is a significant predictor of 1-year cardiac events for Japanese population, and its presence augments the risk especially in the elderly patients.