The American Heart Association, American College of Cardiology and National Institute of Health are all against chelation therapy for cardiovascular disease. At the very least, it has never been shown scientifically to be beneficial. Even further, clinical trials to study it were abandoned for being considered “unethical, dangerous, pointless and wasteful.”
In addition to removal of the target element (usually calcium), chelation will also remove other heavy metallic elements from the body, the long-term hazard of which is unknown and worrisome. I don't know of a single cardiologist who endorses it.
A few small, non-scientific studies have claimed success but many believe that actually came from their recommendations of “quitting smoking, losing weight, eating more fruits and vegetables, avoiding saturated fats, and exercising regularly.” Now, that I do strongly endorse. And if you already do those good things, then you should be in pretty good shape.