Cardiac diagnostic tests

“Cardiovascular disease” is a term for a group of diseases that affect your heart and blood vessels, including stroke, coronary artery disease, heart failure, heart valve disease, atherosclerosis (hardening of the arteries), high blood pressure, or cardiac arrhythmias. If your doctor thinks you may have cardiovascular disease, you should expect further tests.

Fortunately, there are many types of cardiac diagnostic tests available. Your doctor will order tests based on your specific medical situation. Tests include:

Blood tests

What it is: A needle inserted into your vein by a doctor to draw a small amount of blood.
What it measures: Cholesterol, proteins such as lipoprotein (a) or troponin and inflammatory markers such as C-reactive protein. Your doctor will order specific tests based on your possible diagnosis.
Accustomed to: Assess your risk of cardiovascular disease along with a physical exam and your medical history. Specific tests such as troponin levels can confirm whether damage to your heart muscle has already occurred.

Blood pressure monitoring

What it is: An arm cuff that measures your blood pressure during clinic visits. You may also need to measure your blood pressure at home.
What it measures: How much pressure your blood puts on your arteries when your heart pumps.
Accustomed to: Provide an early warning system for heart disease even if there are no symptoms, as high blood pressure can damage your heart muscle and blood vessels over time.
Other uses: In the event of a medical emergency, blood pressure monitoring can alert the team to sudden changes in condition.

According to the American Heart Association, blood pressure categories are as follows:

Normal: Less than 120 mm Hg systolic (upper value) and 80 mm Hg diastolic (lower value)
Elevated: 120-129 mm Hg systolic and less than 80 mm Hg diastolic
Stage 1 hypertension: 130-139 mm Hg systolic or 80-89 mm Hg diastolic
Stage 2 hypertension: 140 mm Hg or higher systolic or 90 mm Hg or higher diastolic
Severe hypertension: 180 mm Hg or higher systolic or 120 mm Hg or higher diastolic

Chest x-ray

What it is: An x-ray showing the heart, lungs and chest. It cannot show the structures inside the heart.
What it measures: A chest x-ray shows the size, shape, and location of the heart and lungs. Some nearby blood vessels are also shown in the image.
Accustomed to: Help diagnose the cause of symptoms such as chest pain, fever, difficulty breathing, or a persistent cough.

Echocardiogram (heart ultrasound)

What it is: A test that uses sound waves to create images of the heart. The most common type is called a transthoracic echocardiogram (TTE), in which the doctor moves the ultrasound wand over your chest. There’s also a transesophageal echocardiogram (TEE), in which your doctor inserts the ultrasound wand into your throat to get a clear view of your heart or aorta.
What it measures: The structure of your heart and how well it works, including its pumping strength and heart valve health.
Accustomed to: Help diagnose heart muscle damage, heart valve disease or heart failure.

Electrocardiogram (EKG or EKG)

What it is: Electrodes attached to your body that are connected to an EKG machine.
What it measures: Electrical waves in the heart and how fast and regularly your heart beats. Every time your heart beats, it creates an electrical wave. This wave compresses the heart muscle, pumping blood out of the heart.
Accustomed to: Diagnose and monitor many heart diseases, including heart attack, heart failure, heart valve disease, coronary artery disease, and cardiac arrhythmia (irregular heartbeat).
Other uses: May help diagnose pulmonary embolism, pericarditis, or abnormal levels of potassium or calcium in the blood.

Tilt table test

What it is: A test in which you lie on a special motorized table that moves from flat to an angle that mimics sitting. A technician will monitor your vital signs and symptoms such as slow heart rate, low blood pressure, fainting, lightheadedness, or nausea.
What it measures: Whether blood buildup in your veins is causing these symptoms.
Accustomed to: Help diagnose postural orthostatic tachycardia syndrome (POTS), vasovagal syncope and similar conditions.

Take a cardiac stress test

What it is: A test that requires walking on a treadmill or riding an exercise bike in a medical setting while connected to a monitoring device. Your doctor will also check your blood pressure after the test.
What it measures: How well your heart pumps blood.
Accustomed to: Diagnose coronary artery disease or find the cause of symptoms such as chest pain or shortness of breath.
Other uses: May also help predict risk of heart attack or suitability for surgery or a safe level of exercise.

Holter monitoring

What it is: A small wearable device that tracks your heart rhythm over 24 to 48 hours. Your doctor may order Holter monitoring if you have had fainting spells, dizziness, or an EKG did not provide enough information.
What it measures: Your heart rhythm throughout the test period.
Accustomed to: Detect irregular heartbeat (arrhythmia).

Cardiac CT scan

What it is: X-rays taken from many angles are used to create a detailed 3D image of your heart and surrounding blood vessels. Some high-resolution scanners can even show your heart in motion.
What it measures: The anatomy and function of your heart, heart valves, blood vessels, and related structures.
Accustomed to: Diagnose or monitor chest pain, artery blockages, and problems with the aorta or heart valves.
Other uses: Commonly used to plan cardiac procedures, including minimally invasive or robotic heart surgery.

Cardiac MRI scan

What it is: A magnetic field and radiofrequency waves are used to create detailed 3D images of blood vessels and the inside of the heart, including the heart valves.
What it measures: How well the heart and heart valves function and whether enough blood flows through your major blood vessels.
Accustomed to: Diagnose or monitor advanced or complicated heart disease after other tests have been performed.

Cardiac catheterization

What it is: A small tube or catheter that is inserted into one of your large veins to lead it to your heart. There, the doctor will check your heart’s blood flow or the inside of your blood vessels for problems.
What it measures: How well your heart works and how healthy your heart valves and blood vessels are.
Accustomed to: Diagnose blocked or narrowed arteries or valves.
Other uses: Unlike other diagnostic tests, cardiac catheterization allows your doctor to immediately move from diagnosis to corrective procedure if necessary. Possible procedures include cleaning a blocked artery or a partially blocked heart valve, or taking tissue samples from the heart to examine under a microscope.

Coronary angiogram

What it is: A special type of cardiac catheterization. Once your doctor inserts the catheter into your heart, he or she will take X-rays with contrast dye to check for blockages in the large arteries near your heart.
What it measures: How healthy the arteries near your heart are.
Accustomed to: Diagnose and resolve clogged arteries near your heart.

This educational resource was created with support from Merck.

Darcy Lewis

Darcy Lewis writes about health and medicine from Chicago, focusing on clinical medicine, the business of health care, and health policy. A former National Cancer Reporting Fellow, she also completed the Medicine in the Media Fellowship at Dartmouth College in the summer of 2024.

Darcy focuses on helping patients make better healthcare decisions and helping clinicians stay current on clinical developments. That’s why he was drawn to writing about oncology. She has written about cancer for patient-focused publications such as Everyday Health, Cancer Today, and HealthyWomen.org, as well as professional content and articles for ASCO Daily News, Oncology Live, Targeted Therapies in Oncology, Medscape, MedPage Today, McKesson, Cardinal Health, evi-Core, and many others. One of her articles for Oncology Live won the 2020 ASJA Award for Best Technical Article, while an annual report for the Pulmonary Fibrosis Foundation won the 2024 ASJA Award for Long-Form Content.

Darcy currently serves as President of ASJA, having previously served as Vice President, Secretary and Chair of the Website Task Force, a multi-year effort to modernize ASJA’s communications with members and the public.