The Greek patient had been so dangerously ill that he had been kept in hospital for four months. He had suffered at least two heart attacks and his cardiac muscle was too weak to push enough blood around his body.
Drug treatment and other surgical devices had failed to improve his condition.
In a radical attempt to save his life, surgeons implanted a Jarvic mechanical device into his heart to divert blood away from the damaged pumping chamber.
In many patients that is enough for the heart to begin to heal - sometimes so well that the mechanical pump can be safely removed weeks or months later.
But in Ioannis' case the cardiac muscle had been badly damaged. So surgeons injected six million stem cells that they had earlier extracted from his bone marrow.
The stem cells kickstart a recovery by building new muscle and releasing chemicals that attract new blood vessels into the damaged areas.