Lee admitted to SGH for atrial flutter.  Reuters:

SINGAPORE (Reuters) – Lee Kuan Yew, 84-year-old founder of modern Singapore, has undergone successful treatment for an abnormal heart rhythm at a local hospital, his press secretary said on Saturday.

“He is still in the hospital,” Yeong Yoon Ying told Reuters, adding that he would remain under observation for the time being.

It was the first time that Lee has suffered from the complaint, known medically as “atrial flutter”, Yeong said.