Do you need to shave chest hairs for ecocardiogram?

For most men, this is not necessary at all. The sensors they put on your chest and stomach can deal with a fair amount of body hair. If you are very, very hairy (and some men are), then they might need to shave a small area so the sensor is in proper contact with your skin. But then the area is so small they shave, and since the man would be very hairy in this case, the spot that was shaved is not readily noticeable afterward.