Depression is commonly seen in patients with cardiovascular disorders. In recent studies it has been shown that mild to moderate depression symptoms were associated with increased likelihood of mental stress-induced myocardial ischemia (MSIMI), which is a risk factor of poor cardiac outcome. In this project, the investigators aim to assess the treatment of mental stress-induced myocardial ischemia in ischemic heart disease patients with mild to moderate depressive symptoms. This study is a six-week double-blind placebo controlled study to examine the effects of escitalopram on mental stress-induced myocardial ischemia. This study will look to show that patients with ischemic heart disease who are treated with escitalopram will exhibit a significant improvement of MSIMI at the end of week 6 compared to patients receiving placebo.