A diagnosis of heart failure is based on a person's risk factor assessment, physical examination, laboratory tests, and other medical tests. In life-threatening situations, emergency treatment is started before the diagnosis is finalized.

Risk factor assessment

A heart failure risk factor assessment is based on person's medical history and the medical history of their family members. A doctor or other healthcare provider gathers information by asking specific questions. A questionnaire is often used to help organize the information.

The medical history contains information about a person's:
- Health (high blood pressure, diabetes, previously diagnosed heart disease condition, thyroid condition)
- Lifestyle (physical activity, smoking, alcohol use)
- Drug use (prescription and over-the-counter medications, supplements, herbs, illegal drugs)
The family medical history contains information about health problems of family members.

Physical examination

The physical examination helps identify any heart disease symptoms. In addition to measuring a person's blood pressure and pulse, the doctor:

Listens to the chest for abnormal heart and lung sounds.
Examines the person's eyes, arms and legs, and skin.

Laboratory tests

Laboratory tests are ordered based on a person's risk factor assessment and physical examination. The tests checks for test results that fall outside of the normal ranges. Laboratory tests for heart failure may include:

Blood chemistry test (includes serum sodium, potassium, chloride, carbon dioxide, and blood urea nitrogen)
BNP (brain natriuretic peptide, which is a cardiac biomarker)
Cardiac enzymes (checks creatine kinase, myoglobin, and troponin)
Complete blood count
C-reactive protein test (blood protein that is a sign of inflammation)
Fasting glucose test (checks blood sugar level)
Lipoprotein profile (checks cholesterol and triglyceride levels)
Liver function test
Urinalysis

Medical tests

Additional medical tests help:

Identify the presence of a person's heart failure risk factors.
Rule out other diseases.
Identify the presence and severity of heart failure.
Determine a person's treatment options.

A person's risk factor assessment and physical exam determine which medical tests the doctor will order. Tests for heart failure may include:

Chest CT scan
A chest CT scan (computed tomography scan) uses X-rays to produce cross-sectional computerized images of the heart and lungs. The CT scan identifies an enlarged heart, fluid in the lungs, and lung disease.
Chest X-ray
A chest X-ray uses electromagnetic radiation to produce images of the heart, lungs, and blood vessels in the chest.
Coronary angiography with cardiac catheterization
Coronary angiography uses X-rays to examine the coronary arteries after a radiopaque substance is injected into a coronary artery using cardiac catheterization. Cardiac catheterization passes a thin, flexible tube through a coronary artery or into the heart's chambers.
Echocardiogram
An echocardiogram uses sound waves (ultrasound) to create moving images of the heart. The test identifies blood flow, heart contractions, and muscle damage.
Electrocardiogram (ECG, EKG)
An ECG measures the heartbeat's rate and regularity.
Magnetic resonance imaging (MRI)
MRI uses strong magnetic fields, radio waves, and a computer to create images of the structure of the heart without radiation or surgery.
Nuclear heart scan
A radioactive tracer is injected into a person's bloodstream, and then pictures are taken of the heart's blood flow.
Stress test
A stress test measures ECG and blood pressure while people exercise or after they take medication to make their hearts beat faster.