UFC fighter Allan Nascimento has died at the age of 34 after suffering a suspected heart attack in his sleep. UFC fighter Allan Nascimento has died at the age of 34 after suffering a suspected heart attack in his sleep. Credit: Instagram @allannascimentoUFC fighter Allan Nascimento has died at the age of 34 after suffering a suspected heart attack in his sleep. In a statement, the UFC said Nascimento was found unresponsive on Monday morning after suffering a medical episode overnight. “This morning, Monday, August 3rd, our beloved flyweight fighter, Allan Nascimento, was found unresponsive after suffering an apparent heart attack in his sleep,” the company said on social media.