Olympic champion Kyle Chalmers says surgery for a worsening heart condition was a success.

The teenage swimming star opted to sit out next month's world championships to treat his supraventricular tachycardia - a recurrent rapid heartbeat that is normally not life-threatening.

"Double thumbs up because this time my heart surgery was successful! Thank you all for the support," Chalmers, 18, said on Instagram.

Chalmers, the 100m freestyle gold medallist at last year's Rio Games, made the decision last month to have his second round of heart surgery after increasingly suffering symptoms, including an abnormally fast heart rhythm.

He said a previous heart operation did not work.

"I have been swimming with an ongoing heart condition known as supraventricular tachycardia and have increasingly begun to suffer from an abnormally fast heart rhythm during training and competitions, which now requires surgery," Chalmers said on May 24.

Chalmers previously said he would set his long-term sights on qualifying for the 2018 Commonwealth Games on the Gold Coast.

AAP