Taking antidepressants may raise the risk of heart disease in men. They can thicken artery walls through an as yet unknown mechanism.
The drugs seem to accelerate atherosclerosis by increasing the thickness of the "intima media", the inner and middle layers of the arteries. They particularly affect the carotid arteries that feed blood to your brain.
Most people have heard the "chemical imbalance" theory and believe it is true. It is important to realize that there is no scientific evidence for this theory. There is no credible scientific lab test showing the presence or absence of mental disease.