Okung noted that he consulted doctors after experiencing "unusual chest pain" during a June 1 practice:
The 31-year-old veteran said doctors told him he likely saved his life by seeking treatment.
L.A. placed Okung on the non-football illness list Wednesday upon the opening of training camp after it was previously reported that he was dealing with a "serious medical issue."
In his statement, Okung said his goal is to be back on the field this season, although he provided no timeline for his potential return.
Okung is a two-time Pro Bowler who has spent the past two seasons with the Bolts. He was originally selected by the Seattle Seahawks with the No. 6 overall pick in the 2010 NFL draft and spent six seasons with the franchise before joining the Denver Broncos for one campaign in 2016.
He signed a four-year, $53 million deal with the Chargers in 2017 and has been a stalwart at left tackle ever since.
During his two seasons in L.A., Okung has appeared in and started 30 of a possible 32 games and was named to the Pro Bowl in 2017.
While he has remained largely injury-free of late, Okung has appeared in all 16 games in a single season just once during his career (2016), and he missed at least two games in five of his first six seasons.
The Chargers must now brace for the possibility that they will be without him for a significant period of time.
If Okung is not ready for the start of the regular season, rookie third-round pick Trey Pipkins is the top candidate to step in as the starting left tackle and the blindside protector for quarterback Philip Rivers.