On 13 September 2008 , Lee , 84 , underwent successful treatment for abnormal heart rhythm ( atrial flutter ) at Singapore General Hospital , but he was still able to address a philanthropy forum via video link from hospital . On 13 September 2008 , Lee , then 84 , underwent successful treatment for abnormal heart rhythm ( atrial flutter ) at Singapore General Hospital , but he was still able to address a philanthropy forum via video link from hospital .