Coach Gregg Popovich said Aldridge informed the team "he felt a little odd" during San Antonio's 112-102 loss at Oklahoma City on Thursday, leading to the diagnosis.
The Spurs are dealing with injuries to starters Kawhi Leonard and Tony Parker, but Aldridge's ailment shocked the team and Popovich.
"Somebody says a heart, you start thinking a little more possible long-term kind of stuff, that's a little scary," Popovich said. "But you don't go there yet. They're doing tests. They did some tests today and they're going to continue it on Monday. He's going to see some people on Monday, and based on what they do and see, we'll figure then what we're really looking at. We really don't know right now."
Aldridge has had heart issues in the past and was diagnosed with Wolff-Parkinson-White syndrome - an abnormality that can cause a rapid heartbeat - as a rookie in 2007.
"All parties have concluded that at the current time it is best for Aldridge to refrain from play until further tests and examinations are completed," the Spurs said in a statement.
Aldridge missed the final seven games of his rookie season after doctors used an ablation - a procedure designed to treat tissue in the heart to make the heartbeat regular again - to treat him and get him back on the court. He also needed an ablation during training camp in 2011, but was able to return to the court in time to play in the preseason and made the All-Star team for Portland that season.
The Spurs were well aware of Aldridge's heart issue when they signed him to a max contract as a free agent in 2015. It has always been considered a minor situation and he has been able to return to playing relatively quickly after each episode, but they still weren't taking any chances.
"Unexpected, but it's a sensitive issue, so we want to make sure that he's fine," Spurs guard Manu Ginobili told reporters at the team's shootaround on Saturday morning. "The most important thing is to have him healthy. We'll wait as long as is necessary for him to feel secure and sure, and the team, too."
The news for Aldridge comes on the heels of Leonard being placed in the league's concussion protocol. It means the Spurs will play Golden State on Saturday night without their two best players.
Leonard was struck on the side of the head by Thunder guard Victor Oladipo during the third quarter of the Spurs' loss. Leonard must be symptom-free as he progresses through a league-mandated series of stress tests that include jogging and non-contact drills.
"He's moving through the protocol," Popovich said. "We expect and hope he will be fine by the end of it. It just takes a while. The next possible game is Monday and I'm hopeful he will be ready for that."
San Antonio, which was 1 1/2 games behind NBA-leading Golden State entering Saturday's showdown, hosts Atlanta on Monday.
"This is tough when you lose your two best scorers in a single day," Ginobili said. "This is tough to face."
But the Warriors will be short-handed as well. Coach Steve Kerr is resting Stephen Curry, Klay Thompson, Draymond Green and Andre Iguodala at the end of a grueling 13-day stretch of the schedule.
The 6-foot-11 Aldridge is averaging 17.3 points and 7.4 rebounds for the Spurs, who also are missing point guards Parker (back) and Dejounte Murray (groin).
|Eric Gay/Associated Press|
LAMARCUS ALDRIDGE OUT INDEFINITELY WITH HEART ARRHYTHMIA
San Antonio Spurs star LaMarcus Aldridge will be out indefinitely while undergoing further evaluation for a minor heart arrhythmia.
Losing Aldridge would be a significant blow for the Spurs as they attempt to keep pace with the Golden State Warriors in the top-heavy Western Conference.
Aldridge is a proven playmaker who has earned a spot in five All-Star Games and on four All-NBA teams. In his first season with the Spurs after nine campaigns with the Portland Trail Blazers, he averaged 18.0 points and 8.5 rebounds per contest. He has followed that up with 17.3 points, 7.4 rebounds and 1.1 blocks in 2016-17.
His scoring average last year, which was his lowest since 2009-10, snapped a streak of five seasons in a row with more than 21 points per contest. Part of that was a function of how deep San Antonio was, but it relied on him more in the playoffs. He posted 21.9 points per game in the postseason and helped lead the Spurs to the second round before they lost to the Oklahoma City Thunder.
Aldridge is valuable on the glass and in the mid-range game, which opens up the offense and allows guards to run pick-and-pops, but San Antonio does have other pieces to shoulder the load until he returns.
In the offseason, the Spurs signed Pau Gasol, a future Hall of Fame candidate who can do many of the same things as Aldridge. San Antonio also added veteran David Lee, who has on his resume eight seasons with double-digit scoring averages.
The Spurs could even go with a small-ball look if needed, with Kawhi Leonard playing a hybrid forward role.
San Antonio may have some options, but it is difficult to envision the Spurs beating the Warriors in a potential postseason showdown without Aldridge.
Spurs’ LaMarcus Aldridge out indefinitely after minor heart arrhythmia
LaMarcus Aldridge is out indefinitely for the Spurs after experiencing a minor heart arrhythmia.
The team announced the news Saturday ahead of their game with the Warriors. Aldridge experienced an irregular heartbeat and will be held out for further testing. How long he will be out remains to be seen.
The Spurs are also without Kawhi Leonard, Tony Parker and Dejounte Murray for Saturday’s game.
Aldridge, 31, is averaging 17.3 points and 7.4 rebounds this season, his 10th in the NBA.