The 24-year-old left-hander suffered the injury during his first start of the season, which saw him experience a drop in velocity in the later innings. He started to play catch again about 10 days later but Heaney felt lingering tightness while playing catch from 90 feet during his third session in Minnesota on April 17 and ceased throwing, as tightness lingered near his pitching elbow.
"The healing rate has slowed," the Angels said in a statement, "and we want to take every precaution with Andrew throughout this process."
Acquired for longtime second baseman Howie Kendrick in December 2014, Heaney put together a strong rookie season, with a 3.49 ERA in 18 starts, and began 2016 as the Angels' No. 2 starter. Angels manager Mike Scioscia said the most recent development hasn't heightened his concern.
"Right now he's at a little bit of a plateau," Scioscia said. "I don't think it's abnormal for rehab to at times plateau, but that's where he is right now. Hopefully he'll bust through this and come out on the other side a hundred percent."
• Left fielder Daniel Nava, on the DL with tendinitis in his left knee, will work out in Arizona while the team is on a six-game road trip through Arlington and Milwaukee. Nava, eligible to be activated as early as Sunday, hopes to begin a rehab assignment with Class A Advanced Inland Empire by Monday.
• Johnny Giavotella was out of the lineup Wednesday, one day after what appeared to be a slump-busting three-hit game. Scioscia said he wanted to utilitze more left-handed bats against righty Chris Young, prompting Cliff Pennington to start at second base and Ji-Man Choi to be the designated hitter, instead of C.J. Cron.
• Angels bullpen coach Scott Radinsky will not be with the team on its upcoming six-game road trip through Arlington and Milwaukee and isn't expected to serve in his role in the immediate future. Radinsky was hospitalized for chest pains on April 13 and briefly met up with the team this past Friday.
Alden Gonzalez has covered the Angels for MLB.com since 2012. Follow him on Twitter @Alden_Gonzalez and Facebook , and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.