Top Star underwent a thrombolysis procedure on Aug. 18 to successfully clear a blood clot.
The Philadelphia Phillies’ World Series hopes took a major blow with Wheeler landing on the 15-day injured list due to a blood clot in his right arm. His timeline to return is still uncertain, according to ESPN’s Jeff Passan.
Wheeler had been putting together another Cy Young-worthy campaign, posting a 10-5 record with a 2.71 ERA across 24 starts, while leading the majors with 195 strikeouts. But over his last six outings, the 35-year-old ace had started to show signs of decline.
Since his dominant one-hit shutout against the Reds on July 6, Wheeler had given up at least two runs in each start, struggling with command and losing some velocity — issues now explained by the clot.
Zack Wheeler’s symptoms & the different types of blood clots
Although doctors haven’t specified the exact type of blood clot Zack Wheeler has, the two most common forms in the shoulder area are deep vein thrombosis (DVT) and venous thoracic outlet syndrome (VTOS), a variation of thoracic outlet syndrome.
DVT often develops after intense physical activity, such as pitching or rowing. Typical symptoms include arm or hand swelling, pain radiating into the hand or forearm, shoulder discomfort, and sometimes weakness in the hand.
VTOS, on the other hand, stems from repetitive movements that strain or compress the structures in the thoracic outlet — the space just above the first rib and behind the collarbone. For athletes, especially pitchers, this condition can cause swelling, aching, or a feeling of heaviness in the dominant arm or hand.
Following his Friday night start against the Nationals, Zack Wheeler reported feeling “a little heaviness” in his right shoulder, Phillies head athletic trainer Paul Buchheit told MLB.com’s Todd Zolecki.
“Zack had been improving after dealing with some shoulder soreness,” Buchheit explained. “But yesterday his symptoms changed, and the doctors did an excellent job quickly identifying the issue and moving the diagnosis forward.”
Treatment options & return-to-play possibilities
Although DVT and TOS blood clots differ, their treatment approaches are generally the same, involving both nonsurgical and surgical methods.
In less severe cases, rest alone may help dissolve the clot. More commonly, though, doctors prescribe blood thinners to aid in breaking it down. Patients usually remain on these medications for at least three months, which would effectively rule Wheeler out for the rest of the season.
If additional intervention is needed, surgery known as a first rib resection may be considered. This procedure, often used for thoracic outlet syndrome, involves removing the first rib and any nearby tissue or scar tissue contributing to the problem.
Should Wheeler undergo this operation, the typical recovery period is about 10 months, putting his earliest possible return around mid-June 2026.
Other MLB pitchers who have dealt with TOS
Wheeler isn’t the first pitcher to face this kind of setback, and he certainly won’t be the last. As recently as 2020, Merrill Kelly of the Diamondbacks underwent surgery for vascular thoracic outlet syndrome and was back pitching by spring training the next year.
Stephen Strasburg’s career, meanwhile, is often associated with his struggles against a more severe form — neurogenic TOS — which ultimately shortened his time on the mound.
Other pitchers who have dealt with TOS include Chris Carpenter (2012), Jaime García (2014), Chris Young (2014), Matt Harvey (2016), and Chris Archer (2020), among several others.
The encouraging part? Each of them managed to return the following season, and research published in the Orthopedic Journal of Sports Medicine indicates no significant decline in performance post-recovery. With so much uncertainty surrounding the Phillies’ ace, that’s as positive an outlook as the team and Wheeler could hope for.