I am 44 years old. i lost 13 kg weight with hard exercise in gym in 6 months. can it be the reason of my recent cad later angioplasty with stent.

Keep exercising: Moderate exercise doesn't cause coronary artery disease. It's possible that as you started exercising harder, you started having symptoms that led to the discovery of coronary artery disease. It's interesting, though, that long-distance endurance athletes, such as marathoners, might have more coronary disease, but that probably takes years of intense training and chronic stress on the body.

Not likely: The effort may have called your attention to the evolving problem. Non smoking, exercize and weight control are generally positive moves.