PARIS French artificial heart maker Carmat's first patient is in a "very satisfactory condition" 12 days after being fitted with the device, the hospital treating him said on Monday.
The 75-year-old Frenchman is eating normally and spent three hours sitting in a chair in the company of his family on Sunday, the team caring for him at the Georges Pompidou European Hospital in Paris said.
"The artificial heart is functioning normally, automatically catering to the body's needs without any manual adjustment necessary," surgeons Alain Carpentier and Christian Latremouille said in a statement issued by the hospital.
Three more patients in France are due to be fitted with the device. In this first series of clinical studies, its success will be judged on whether patients survive with the implant for at least a month.
The people selected suffer from terminal heart failure - when the sick heart can no longer pump enough blood to sustain the body - and would otherwise have only a few days or weeks to live.
The hospital said it would give another update on the first patient in one week. A spokeswoman for Carmat said the company declined to comment at such an early stage in the trial.
Heart-assistance devices have been used for decades as a temporary solution for patients awaiting transplants, but Carmat's bioprosthetic product is designed to replace the real heart over the long term, mimicking nature using biological materials and sensors.
It aims to extend life for patients suffering from terminal heart failure who cannot hope for a heart transplant, often because they are too old and donors too scarce.
Carmat shares were 4.2 percent higher at 112.39 euros at 1308 GMT, trading in volumes more than twice the daily average of the past three months.
(Additional reporting by Alexandre Boksenbaum-Granier; Editing by James Regan)