An xray result showing enlargement of the heart,what does it mean?is this a heart disease?my mom will undergo stress test anytime soon.

Enlargement reflects: heart weakness, whether from ↓ed blood supply/infarction(s), valve problems, high blood pressure, etc. Yet enlargement on CXR may be due to technique, pericardial fat, fluid, etc. A well done heart echo (make sure you see, understand & keep a copy of the video images) typically vastly more accurate/helpful. Stress tests miss all but advanced Ds. Optimize lipoproteins (not cholesterol), HbA1c, BP.