Doctors had diagnosed the Breakers manager with bronchiectasis and Chronic Obstructive Pulmonary Disease.
Following the surgery, Letoa said each morning he thanked his donor.
"I wake up every day and I've got a tradition where as soon as I get out of bed I punch the air and say a little thank-you to my donor," he told Stuff. "The greatest hero I've never met."
Tributes were today being posted on social media.
Breakers star RJ Hampton posted a photo of the two, saying 'Rest in Paradise Fata. I love you 1000x".
It is with heavy hearts that we must say goodbye to our beloved manager Fata Letoa who passed away today.
Fata was truly at the heart of our Breakers family. He saw the best in all of us and embodied everything it means to be a Breaker. A coach, a mentor, a father and a friend. pic.twitter.com/lFBzGixDXK