Consuming foods high in salt content makes you thirsty and drink more water - this is our body's way of keeping the salt and water concentration balanced in our body. But because our body don't easily release the extra salts out of the body (through urine or sweat), the extra fluid is retained in the body as well, worsening the
high blood pressure condition, and making your heart pump extra harder to push all the fluid around your body blood system.
If there is any existing clots or fats on the walls of the blood vessels, the resulting increased blood pressure (from the high salt intake) increases the chances of the clot/fat being dislodged from the wall and travelling along the blood vessels, until it eventually lodges in a small blood vessel, unable to move any further, thus blocking the blood vessel.
This then leads to a
heart attack - an area of the heart affected by the blocked blood vessels starts to "die" from lack of blood supply (carrying
oxygen, nutrients etc).
So it goes like this simply:
High salt = more fluid ratained = higher blood pressure = faster rate of blood flow = higher chances of an existing clot/fat dislodged from the blood vessel wall = higher chances of a blocked blood vessel = higher chances of a cheart attack. :)