Manager Frank Maloney is recovering in hospital after discovering Irish boxer Darren Sutherland hanged in his flat on Monday evening.
Tests showed Maloney had recently suffered heart attack, although it was likely that had happened some time last week.
The Londoner was seen on Sky Sports on Friday night vehemently disputing the result after his fighter John McDermott was on the wrong end of a controversial points loss at the hands of Tyson Fury.
Maloney's spokesman said: "Frank was in shock and taken to hospital for tests which discovered he had had a heart attack.
"He is being kept in for observation and tests but he is sitting up in bed and being allowed to work on his laptop."
Meanwhile, tributes continued to pour in for the tragic Sutherland, who claimed bronze at last year's Olympics and appeared to have a bright future ahead of him.
James DeGale, who beat him in the semi-finals before claiming gold in the middleweight division, was stunned by the news.
"It is very, very sad news - I just can't believe it," DeGale said. "It is a tragedy. First and foremost, my heart goes out to his family.
"I just could not believe it; my heart went to the floor when I heard.
"He was a big part of my Olympic medal journey, and it is just terrible. I just do not know what to say except that he was a brilliant fighter, in fact an excellent fighter, and he was a gentleman outside the ring as well.
"He had an Olympic bronze medal, and his whole life to look forward to. He had a great future, and my heart goes out to everyone who knew him."
Former Great Britain head coach Terry Edwards believes boxing has lost one of its best prospects following Sutherland's death.
"He was such a respectful guy outside the ring," he said. "He had a great rivalry with James. I never heard any bad words between them.
"When he lost to James in the Olympic semi-final he came straight over to the corner and shook our hands and told us we'd got our tactics right, and that was the mark of the man.
"He was a very likeable lad and a total professional. He had a good pro style and I'm sure he would have gone all the way.
"It's such a tragedy - the world was his oyster."
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