How does altiar die in Assassins Creed bloodlines

Altair didn't die in Bloodlines. The details of Altair's death are completely unknown to us, and is never revealed. The only clue given is in Codex Page 30, in which Altair describes his realization that he's soon to pass away, and appears tempted to use the Piece of Eden to elongate his lifespan. Whether or not he did is a mystery.