You are equating calcium level in the blood supply and calcium deposits in the vessels. An exact cause of the calcium deposits has not been identified yet. A logical answer would be the calcium intake from food or supplements. As you know, calcium is very important for the health of the human body. Some patients, older people and menopausal females must have at least 1000 mg calcium intake a day from diet and supplements. So you cannot reduce calcium intake as a form of treatment against calcium deposits.
To have or maintain healthy system vessels can be helped with a heart healthy diet, exercise, no smoking, very little alcohol, etc. Unfortunately there is a genetic component as well..