Is calcium citrate safe for heart patients or does it increase heart and/or stroke risk?

Probably safe: Calcium taken alone without vitamin d may increase the risk of heart problems or stroke because you can not put the calcium in your bones without vitamin d so it will go into the soft tissues including the arteries. Be sure that the calcium citrate has been tested for lead because lead can be found in many calcium supplements. Only a few manufacturers test the raw ingredients for heavy metals.