Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Massive cardiomegaly is unchanged . Left chest wall pacer - defibrillator has leads in stable position . The left retrocardiac region remains opacified with obscuration of left hemidiaphragm . The right lung is grossly clear . There is no pulmonary edema . The mediastinal and hilar contours are stable .
    OUTPUT:
    
1 . Persistent left retrocardiac opacity obscuring the left hemidiaphragm unchanged since at least ___ may reflect persistent atelectasis or pleural effusion . 2 . Persistent severe cardiomegaly .