I just need to know should i listen?

I posted up something lastnight about how I got a catscan done xray. Sonagram done and blood work and echo cardigram done and evrything was fin nothing showed anything wrng with my heart or blood and I ask. If I should worry bout my heart because my friend alwaays scareing me saying I can have cardiac arrest then someone wrote as a answer to me-Tests probably aren't necessary, just a stethoscope and simple blood work. You may end up needing Inderal/Propranolol....now should I listen to that..that's saying that doc aren't always right on the test they do I had so many test done. Should u listen to my friend and this person ho just wrote this to me??????