For an elderly patient with known heart blockage, is a stress-test necessary for a micro-invasive hip replacement (SuperPATH)?

The decision to have a stress test is left to the discretion of your cardiologist. Like any procedure, a thorough pre-operative workup is required for your safety. This includes general medical clearance, as well as any specialty clearance that is deemed necessary (depending on any pre-existing conditions). This would likely involve some sort of cardiac workup in the face of known cardiac issues, regardless of age.