With IHSS or hypertrophic cardiomyopathy, the growth and arrangement of muscle fibers are abnormal, leading to thickened heart walls. The greatest thickening tends to occur in the left ventricle (the heart's main pumping chamber), especially in the septum, the wall that separates the left and right ventricles. The thickening reduces the size of the pumping chamber and obstructs blood flow. It also prevents the heart from properly relaxing between beats and so filling with blood. Eventually, this limits the pumping action.
Many patients have no symptoms. For those who do, the most common are breathlessness and chest discomfort. Other signs are fainting during physical activity, (are your symptoms...strong rapid heartbeats that feel like a pounding in the chest..., and fatigue, especially with physical exertion.
You should get a doctor's evaluation regarding the proper exercise if any for heart muscle desease. Your dx of IHSS is 11 years ago?! Usually, and the guidelines for a stent implant is for an artery occlusion greater than 70%. Apparently, you had angina (chest pain) tha could not be controlled by medication to justify the intervention?!
You doctor should have your medical history and can properly assess your risks and benefits regarding exercise.