My Dad Is 91 Years Old And Had Triple Bypass

My dad is 91 years old and had triple bypass surgery 30 years ago. Takes meds for high blood pressure but all is under control. Do you think a 91 year old needs to get on a treadmill, have an ekg and a nuclear test every year? Actually his doctor wants him in every 6 months. My dad gets very nervous about the treadmill and is wondering if he should refuse it.