LaMarcus Aldridge -- a 7-time NBA All-Star -- just announced he's retiring from the league after learning he played with an "irregular heartbeat."

The 35-year-old Brooklyn Nets star -- who dropped 12 points against the Lakers on Saturday -- made the shocking announcement in an emotional social media post Thursday morning.

"My last game, I played while dealing with an irregular heartbeat. Later on that night, my rhythm got even worse which really worried me even more," Aldridge said.

"The next morning, I told the team what was going on and they were great getting me to the hospital and getting me checked out."

Aldridge says he's "better now" -- but explains, "What I felt with my heart that night was still one of the scariest things I've experienced."

"With that being said, I've made the difficult decision to retire from the NBA. For 15 years, I've put basketball first, and now, it is time to put my health and family first."

Aldridge was the 2nd overall pick in the 2006 NBA Draft -- and spent nearly a decade with the Portland Trail Blazers.

After that, he spent 6 years with the San Antonio Spurs before signing with the Brooklyn Nets in late March.

Aldridge says he's "thankful for everything this game has given me; the great memories, including all the ups and downs, and the friendships I’ve made and will keep with me forever."

"I thank Portland for drafting a skinny, Texas kid and giving him a chance. The city of Portland has given me some unforgettable years. They will always remain in my heart."

"I want to thank the Spurs for letting me into the family and giving me 5 fun years."

"Last but not least, I want to thank Brooklyn. You wanted me for me. In a game that’s changing so much, you asked me to come and just do what I do which was good to hear."

Aldridge ended his statement with this -- "You never know when something will come to an end, so make sure you enjoy it everyday. I can truly say I did just that."