Leg swelling is not a measure of the severity of heart disease because it is not caused by all heart disease, but is associated with right heart failure.
The most common heart disease that causes leg swelling is right heart insufficiency. Due to the decline in right heart function, blood from the heart, which pools in the upper and lower vena cava veins, is unable to transport blood to the lungs, and most noticeably, edema of the legs occurs.
Even in mild right heart insufficiency, depressed functional edema of the ankles can occur. It is more pronounced when the lower limbs are drooping and is relieved when lying down. When right heart insufficiency gets progressively worse, the edema also gets progressively worse.
But some heart disease even if very serious will not cause edema, such as coronary heart disease, arrhythmia patients in the onset of chest tightness, shortness of breath, palpitations and other symptoms, and will not appear lower limb edema.
So the severity of lower extremity edema can only assess the degree of right heart insufficiency, other heart disease need to consult a doctor to determine.