In a statement released to The World Game, Naumoff said: “During the mandatory medical assessment under taken by C.D. Numancia it was found that there was an abnormality of my heart. Apart from this finding there is no issue with my health and fitness.
“After two follow up examinations from professional football related cardiologists in Madrid, and a final consultation with Professor Christopher Semsarian in Sydney the condition was confirmed as Hypertrophic Cardiomyopathy (HCM).
“HCM is a genetic condition which involves thickening of the interior heart wall and introduces a risk of sudden cardiac arrest, in particular for professional athletes during activity.
How long this condition has affected me is unknown, and how this condition was not discovered during my time as a professional in Australia is a question for another day.
As a result of these findings, in conjunction with the risks that come with the condition, the history of players with this condition, recommendations from the cardiac professionals and the international rules of the game, it is with great sadness that I announce my retirement from professional football.”
Naumoff has signalled his intentions to “stay involved in football one way or another”.
He played 55 games for Sydney FC in the Hyundai A-League after making his debut in 2013, appearing in the 2015 grand final against Melbourne Victory and was also a part of the Sky Blues ACL campaign this year.
Naumoff also represented Australia at both under-20 and under-23 level.