from the findings of chest x-ray it is clear that your wife is suffering from heart failure
probably due to ischemic heart disease
now the question is about the next inv. which should be done.
ECG,ECHO is a routine inv. for this patient with abnormal x-ray findings. these will identify the severity of problem.
angiogram is usually done to look the patency of coronary blood vessels. it guides the doctor to take decision about the next specific therapy for the patient.