Salt raises blood pressure. High blood pressure causes heart disease, including heart attacks, angina and heart failure.
If you can lower your salt intake you will lower your blood pressure and so reduce the chance of getting heart disease.
If you already have heart disease, lowering your salt intake will help to lower your blood pressure and so reduce the strain on your heart.
If you already have heart failure, lowering your salt intake may help to reduce the amount of swelling or oedema that you experience. The oedema happens because your kidneys are not able to get rid of all the salt that you are eating.
Read what the British Heart Foundation says about salt here.