The first patient fitted with an artificial heart made by the French company Carmat has died, the hospital that had performed the transplant in December said on Monday.
The 76-year-old man died on Sunday, 75 days after the operation, the Georges Pompidou European Hospital in Paris said in a statement, adding that the cause of his death could not be known for sure at this stage.
When he was fitted with the device, the man was suffering from terminal heart failure - when the sick heart can no longer pump enough blood to sustain the body - and probably had only a few weeks, or even days, to live.
Representatives of Carmat could not immediately be reached for comment.
The bioprosthetic organ product is designed to replace the real heart for up to five years, mimicking nature's work using biological materials and sensors. It is aimed at helping the thousands of patients who die each year while awaiting a donor, and reducing the side-effects associated with transplants.
Three more patients in France with acute heart failure are due to be fitted with the device.
The clinical trial will be considered a success if patients survive with the implant for at least a month.
If it passes the test, the device will then be fitted into about 20 patients with less severe heart failure.
"The doctors directly involved in the post-surgical care wish to highlight the value of the lessons learned from this first clinical trial, with regard to the selection of the patient, his surveillance, the prevention and treatment of difficulties encountered," the hospital said in its statement.