What diagnostic test is considered the best tool for diagnosing

heart failure?

Blood tests. Blood tests are used to evaluate kidney and thyroid function as well as to check cholesterol levels and the presence of anemia. Anemia is a blood condition that occurs when there is not enough hemoglobin (the substance in red blood cells that enables the blood to transport oxygen through the body) in a person's blood.

B-type Natriuretic Peptide (BNP) blood test. BNP is a substance secreted from the heart in response to changes in blood pressure that occur when heart failure develops or worsens. BNP blood levels increase when heart failure symptoms worsen, and decrease when the heart failure condition is stable. The BNP level in a person with heart failure -- even someone whose condition is stable -- is higher than in a person with normal heart function. BNP levels do not necessarily correlate with the severity of heart failure.

Chest X-ray. A chest X-ray shows the size of your heart and whether there is fluid build-up around the heart and lungs.

Echocardiogram. This test shows the heart's movement.

Ejection fraction (EF). A test called the ejection fraction (EF) is used to measure how well your heart pumps with each beat to determine if systolic dysfunction or heart failure with preserved left ventricular function are present. Your doctor can discuss which condition is present in your heart.

Electrocardiogram (EKG or ECG). An EKG records the electrical impulses traveling through the heart.

Cardiac catheterization.

Stress Test.
There isn't just one best tool or test for diagnosing heart failure. There are even more tests than what is listed here.