Higher salt levels raise blood pressure. High blood pressure leads the body to strengthen blood vessel walls, which make them less flexible. Less flexible blo

Higher salt levels raise blood pressure. High blood pressure leads the body to strengthen blood vessel walls, which make them less flexible. Less flexible blood vessels put more strain on the heart, which in cardiac patients (who are operating with a damaged heart) is obviously suboptimal. There is a ton of studies about this and heart patient life expectancies have been going up for the last several decades because we have figured this (and a few other things) out.