Is stress bad for the heart?

Highly variable : But stress a known factor for development of cad.

Stress is never good: It can be said that stress affects the body in many ways. Stress with job, school, family causes your body to be in "panic mode" and can thereby cause stress on your internal organs and systems. One of the most common symptoms of stress that i see in practice is heart palpitations and is often due to stress after other causes have been ruled out. If you are having these symptoms, get checked out.

Chronic stress bad: "stress" is not automatically bad for the heart. In fact your heart is built to deal very well with "acute" stress. Long-term stresses can be factors in heart disease, though. Consider chronically poor sleep; unhealthy diets with processed foods resulting in weight gain and disturbed lipid balance; chronic sympathetic overdrive leading to cortisol elevation and hypertension, etc.