Korelasi nilai fungsi sistolik ventrikel kiri antara echocardiography 2D dengan dual source computed tomography (DSCT) jantung pada penyakit jantung koroner stabil di RSUPN Cipto Mangunkusumo = Correlation of left ventricular systolic function value between echocardiography 2D and cardiac dual source computed tomography (DSCT) in stable coronary heart disease at Cipto Mangunkusumo Hospital