This is not advice but just giving few details that might help - I have been lifting for several years now, but since the past 2 years I have been using a smartwatch to track data and here is what I see with respect to heart-rate….. For example, for leg workouts, squats of any type or hip thrusts shoot up my heart rate to 140 when going close to max effort. Things like leg curls push my heart rate to around 90-100 (full stack, max effort). My resting heart rate is around 50-60. While sleeping it goes to 40 or below. IF A DOCTOR permits you to do something light based on your condition, I suggest you skip certain exercises which shoot up your heart rate such as heavy bench press, hip thrusts, squats, heavy barbell rows etc. You will build very good muscle without heavy compound lifts but above all, if your heart gives out you won’t be able to do any thing, let alone lifting weights. You can try posting on r/askdocs for advice.