There is no single “heart test.” The term covers dozens of different tests, each designed to evaluate a specific aspect of heart health. The most common ones you’ll hear about are the electrocardiogram (ECG or EKG), the echocardiogram (echo), and the stress test. Which one your doctor orders depends on whether they’re checking your heart’s electrical signals, its physical structure, blood flow through your arteries, or signs of muscle damage.
Electrocardiogram (ECG or EKG)
An electrocardiogram records the electrical activity of your heart. Small sticky patches are placed on your chest, arms, and legs, and the machine traces the pattern of each heartbeat on a screen or printout. The whole process takes about 10 minutes and is completely painless. It can detect abnormal heart rhythms, called arrhythmias, and can sometimes reveal heart muscle damage.
You’ll see this test referred to as both “ECG” and “EKG.” They’re the same thing. “EKG” comes from the German spelling, Elektrokardiogramm, and stuck around in English-speaking medicine because “ECG” could be confused with another test abbreviation. If your doctor mentions either one, they mean this test.
Echocardiogram (Echo)
An echocardiogram is an ultrasound of your heart. While an ECG measures electrical signals, an echo produces a detailed picture of the heart’s physical structure. The images show the size of each of the heart’s four chambers, how the valves open and close, and how well the main pumping chamber is pushing blood out to the body.
The standard version, called a transthoracic echocardiogram (TTE), involves a technician pressing an ultrasound wand against your chest. It takes about 45 minutes. A transesophageal echocardiogram, where a small ultrasound probe is guided down your throat to get closer images, takes between one and one and a half hours including prep and recovery. This version is less common and only used when the standard approach can’t get clear enough pictures.
Stress Tests
A stress test monitors your heart while it’s working hard. The most common version has you walking on a treadmill or pedaling a stationary bike while a team tracks your heart rate, blood pressure, oxygen levels, and electrical activity. The speed and incline are gradually increased based on your fitness level. If you can’t exercise, you receive medication that mimics the effect of physical exertion on your heart. A stress test typically takes about an hour.
Stress tests are primarily used to detect coronary artery disease, the narrowing of arteries that supply blood to the heart. They’re also used to establish safe exercise levels after a heart attack or heart surgery. Several variations exist:
- Exercise stress test: The basic version using a treadmill or bike with ECG monitoring.
- Stress echocardiogram: Combines exercise with ultrasound imaging to watch how your heart walls move under strain.
- Nuclear stress test: Uses a small amount of radioactive tracer injected into a vein so a special camera can compare blood flow to your heart muscle at rest and after exertion. A decrease in blood flow signal typically indicates a blockage in one or more arteries.
The imaging-based stress tests are more accurate than a standard exercise ECG, especially for people whose resting ECG already shows abnormalities. They can also pinpoint where in the heart the blood flow problem is located, not just whether one exists.
Portable Heart Monitors
Some heart rhythm problems don’t show up during a brief office visit. In those cases, your doctor may send you home with a wearable monitor to catch irregular rhythms as they happen during your normal daily life.
A Holter monitor is a small, battery-powered ECG device with patches attached to your chest. You wear it continuously for one to two days, or in some cases one to two weeks. It records every heartbeat during that period. Event monitors and mobile continuous outpatient telemetry (MCOT) devices work similarly but are worn for longer stretches, typically one to four weeks, and up to 30 days. These are commonly used to investigate palpitations, unexplained fainting, or heartbeats that feel too fast, too slow, or irregular.
Blood Tests for Heart Damage
When doctors suspect a heart attack, they order blood tests that look for proteins released by injured heart muscle. The most important of these is cardiac troponin. The American Heart Association considers troponin the best biomarker for confirming a heart attack. It enters the bloodstream soon after heart muscle is damaged and stays elevated for days, longer than other markers.
Older biomarkers like creatinine kinase (CK) and its subtype CK-MB are less commonly relied on now. CK levels can rise from many conditions unrelated to the heart, making it less specific. CK-MB is more heart-focused and rises four to six hours after a heart attack, but troponin has largely replaced both as the go-to test.
Imaging for Artery Blockages
A coronary calcium scan is a specialized CT scan that looks for calcium deposits in the arteries supplying your heart. Calcium buildup is a sign of plaque, which can narrow arteries and reduce blood flow. The scan takes just a few minutes and doesn’t require any injections or dye. It’s typically used for people at intermediate risk of heart disease to help decide whether preventive treatment is worthwhile. It’s not recommended for people already known to be at high risk or who have already had a heart attack, stent, or bypass surgery, since those patients already have the information the scan would provide.
For a more definitive look, cardiac catheterization (also called coronary angiography) threads a thin tube through a blood vessel, usually in the wrist or groin, up to the heart. Dye is injected so the arteries show up on X-ray in real time. This is the gold standard for mapping blockages and is often done when a less invasive test has already flagged a problem. If a significant blockage is found during the procedure, doctors can sometimes treat it on the spot with a stent.
Other Specialized Heart Tests
A few less common tests round out the list. A tilt table test evaluates whether you’re prone to sudden drops in blood pressure when you stand, which can cause fainting. You lie strapped to a table that slowly tilts you upright while your blood pressure and heart rate are monitored. A PET scan of the heart uses a radioactive tracer to map blood flow through the coronary arteries and can identify areas of heart tissue with permanent damage. Myocardial perfusion scans, sometimes called thallium scans, also use radioactive tracers and a special camera to evaluate blood flow, often as part of a nuclear stress test.
Which test your doctor chooses depends on the specific question they’re trying to answer. Electrical problems call for an ECG or a wearable monitor. Structural concerns point to an echo. Suspected blockages lead to stress tests, calcium scans, or catheterization. And sudden chest pain in an emergency room almost always starts with troponin blood draws and an ECG, because both can be done in minutes and together cover the most urgent possibilities.