* First patient died after 2-1/2 months with the device
* Study looks at survival rate after one month
* Three more terminally ill patients due to try it
* Carmat shares, suspended Tuesday, hit 2-year low (Adds share price reaction, analyst comments, context)
PARIS, March 5 (Reuters) - Carmat shares fell to a two-year low on Wednesday after the death of the first patient fitted with its artificial heart, but the French company said it would proceed with further clinical trials of the device as planned.
Carmat's first patient, a 76-year-old man, died on Sunday in Paris, two and a half months after his transplant.
Before 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 was said to have only a few weeks, or even days, to live.
The hospital that had performed the operation said the cause of his death could not be known for sure at this stage. Carmat said it was too soon to draw any conclusions on the artificial heart, which beat some 7 million times since it was implanted in the patient in December.
Carmat's device is designed to replace the real heart for as much as five years, mimicking nature's work using biological materials and sensors. It aims to extend life for terminally ill patients who cannot hope for a real organ because they are too old and donors too scarce.
Shares in Carmat, which were suspended on Tuesday, fell 10 percent to a more than two-year low at the market open. By 1042 GMT, they were 7 percent lower at 88.32 euros, valuing the company at about 378 million euros ($519.47 million).
"Carmat, first and foremost, wishes to pay tribute to the courage and the pioneering role of this patient and his family," the group said in a statement on Tuesday evening.
"The company stresses that it is too soon to draw any conclusions from the data of a single patient, whatever the duration of the implantation."
Three more patients in France with terminal heart failure and no other therapeutic option are due to be fitted with Carmat's device.
Carmat said it was not planning to publish any information on the results of this feasibility study until an analysis of the trial's data was completed. It will be considered a success if most of the patients survive with the implant for at least a month.
Invest Securities analyst Daniel Anizon, who has a "buy" recommendation on the stock, said in a note that the first patient had exceeded this target, living 74 days with the device. He added that nothing obliged Carmat to establish the cause of the patient's death before implanting the three others, and that this initial study should be completed by mid-year.
Carmat has previously said that if it passed this first safety test, it would fit the device into about 20 more with less severe heart failure later this year, with an aim to request the right to market its device in Europe by 2015.
Portzamparc analyst Arnaud Guerin noted that Carmat shares had spiked ahead of the trials, and that they were sobering up in the face of the high risks tied to the project.
"There is no way we can say today how these clinical trials will turn out," Guerin said. "The way the stock is behaving is rather irrational and not about economic valuations."
Last year, Carmat posted a net loss of 14.6 million euros, after a 17.2 million loss in 2012. In its half-year financial report, it had an operating cash burn of 3.6 million euros.
The company has said it had enough cash and subsidies to fund its activities until 2015. But it could seek an injection of funds from fresh investors at some point to help fund its international expansion, Carmat co-founder Philippe Pouletty said in December.
$1 = 0.7277 Euros Reporting by Natalie Huet and Leila Abboud; editing by William Hardy and Louise Heavens