P502 502 TELEINF 03:32:07 W O R L D N E W S The 18th of September 4.00 p.m. (njxt at 11.00 a.m. Thursday)  MOSCOW - Boris Yeltsin is still in charge of "key issues" but many other decisions are being taken by top aides while the russian president prepares for heart surgery, his chief of staff Anatoly Chubais said Wednesday. In an interview published in the daily Izvestia, Chubais also denied reports that senior officials were trying to undermine National Security chief and chechnya troubleshooter Alexander Ljbed. Despite his ischemia -- a condition that restricts blood flow to the heart -- Yeltsin was still deciding on "key issues," Chubais told Izvestia. Yeltsin, who suffered two mild heart attacks last year, was see next page >>>