Following the retirement of 21-year-old Chris Naumoff in July due to a heart condition, the former Sydney FC striker now believes his old club may have had evidence of his condition months before he was forced to retire, SBS reports.

Naumoff was on the brink of signing his first overseas contract with Spanish side Numancia, before an electrocardiogram (ECG) diagnosed him with Hypertrophic Cardiomyopathy, HCM, a genetic disease which can cause sudden death when the heart is put under severe exertion.

"Obviously it was a total shock, which I wish upon no one to see their dreams come crashing down within a day," Naumoff said.

Under the latest Minimum Medical Standards agreement by Football Federation Australia, every A-League club must make sure each player is given an ECG test in their first year at the club, followed by one test every two years after that.

When asked the FFA said that every player involved in the 2015-16 A-League season completed the health check, although Naumoff claims he was not given an ECG in his three years at the Sky Blues until February this year.

"We were informed the day before training that we were to be called into training to have an ECG test done for that reason. Obviously, each and every player had that test done. I heard nothing back from the results. So as you would guess, I thought everything was fine," Naumoff said.

When Naumoff then did the test in Spain, the results he got back were quite confronting.

"The results did show that there was something wrong with my heart and that I did need further testing. I wasn't made aware of this. Why that's the case? I'm not sure. But this is definitely a thing that's on the results and something that should have been taken further at the time," Naumoff said.

The classy striker went on to play six more games for Sydney following the ECG test in February, which means Naumoff was playing with a life-threatening illness that the club may have be aware of, without him knowing the exact circumstances.

"The question was asked and in terms of getting an answer from whoever needs to answer these questions, (it) is still up in the air," he said.