Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright AP radiograph of the chest . Left chest wall pacemaker - defibrillator has a lead traversing the right SVC terminating in the right ventricle and another lead arriving in the right atrium by way of a left sided SVC draining into the coronary vein . Lungs are normally expanded . There is blunting and opacity at the left costophrenic sulcus which may represent atelectasis , possibly with small pleural effusion , although infection can not be completely excluded . However , this area is partially obscured by the pacer . The remaining lung fields are clear . There is no pneumothorax . The cardiomediastinal silhouette is stable ; the heart is top normal .
    OUTPUT:
    
Progression of what is likely atelectasis at the left base , although infection can not be completely excluded . This could be better evaluated with formal PA and lateral radiographs of the chest .