EKGs: What They Can and Cannot Tell You

An EKG, also called an ECG or electrocardiogram, is a test that records the electrical activity of the heart. It is commonly used to evaluate heart rhythm, heart rate, and certain signs of heart strain or injury.

An EKG can be very helpful, but it does not tell everything about the heart.

What does an EKG show?

An EKG can show:

• Heart rate

• Whether the rhythm is regular or irregular

• Electrical signal patterns

• Certain rhythm abnormalities

• Possible signs of a current or prior heart attack

• Possible heart enlargement or strain

• Certain medication-related electrical changes

An EKG can show how fast the heart beats, whether the heartbeat is steady or irregular, and the strength and timing of electrical signals in different parts of the heart.

Why an EKG may be ordered

An EKG may be considered if you have:

• Chest discomfort

• Palpitations

• Irregular heartbeat sensation

• Dizziness

• Fainting

• Shortness of breath

• Certain medication monitoring needs

• High blood pressure concerns

• History of heart disease

• Abnormal heart rate

What an EKG cannot tell you

An EKG cannot rule out every heart problem. A normal EKG does not always mean the heart is completely healthy. Some heart problems come and go. Some require blood tests, imaging, stress testing, longer rhythm monitoring, or emergency evaluation.

An EKG may not fully evaluate:

• Intermittent palpitations

• Blocked arteries without active changes

• Heart failure severity

• Valve disease severity

• Blood clots

• All causes of chest pain

• All causes of shortness of breath

When an EKG is urgent

Do not wait for a routine outpatient EKG if you have symptoms that could be an emergency.

Call 911 or seek emergency care for:

• Chest pain or pressure

• Trouble breathing

• Fainting

• Severe dizziness

• New weakness on one side

• Facial drooping

• Difficulty speaking

• Severe sweating with chest discomfort

• Pain spreading to jaw, neck, back, or arm

• Severe palpitations with weakness or shortness of breath

Can telehealth help?

Telehealth can help determine whether your symptoms may need urgent care, in-person evaluation, or outpatient EKG referral. If you are having active chest pain, severe shortness of breath, fainting, or stroke-like symptoms, emergency care is needed.

EKG and medication safety

Some medications can affect heart rhythm or the electrical timing of the heart. In some cases, an EKG may be used before or during treatment to improve medication safety.

Final thought

An EKG is a useful test, but it is only one part of heart evaluation. Symptoms, risk factors, vital signs, labs, imaging, and clinical judgment all matter.

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This information is for educational purposes only and does not replace medical advice, diagnosis, or treatment. If you are experiencing severe symptoms, signs of infection, severe allergic reaction symptoms, trouble breathing, or a medical emergency, call 911 or go to the nearest emergency room.