Rio Olympics 100-meter freestyle gold medalist Kyle Chalmers has withdrawn from July's World Swimming Championships to undergo surgery for a worsening heart condition.
Chalmers has supraventricular tachycardia, or recurrent rapid heartbeat, that is normally not life-threatening but can impact on his quality of life.
The 18-year-old Chalmers says "I have had a surgery in the past, and unfortunately, it did not work."
Chalmers said Wednesday it was a difficult decision to miss the world championships in Budapest, but he did so with a longer-term view, setting his sights on the Gold Coast Commonwealth Games in 2018.
In April, he finished second to Cameron McEvoy at the Australian championships.