Luaran Penggunaan Strip Tunggal Perikardium dan Katup Mekanik dalam Penggantian Katup Aorta: Kajian terhadap Left Ventricle Reverse Remodeling, Six Minute Walking Test dan Soluble Suppression of Tumorigenicity-2 = Outcome of Single-Strip Pericardium and Mechanical Valve in Aortic Valve Replacement: Study on Left Ventricle Reverse Remodeling, Six Minute Walking Test and Soluble Suppression of Tumorigenicity-2