Perbandingan Profil Stres Oksidatif dan Penuaan Seluler Pra - Pasca Bedah Pintas Arteri Koroner Lansia dan Kaitannya dengan Lama Rawat di ICU = Comparison of Oxidative Stress Profile and Cellular Aging Before and After Coronary Artery Bypass Surgery in Elderly Patients and Its Relation to Length of Stay in ICU