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How long after potential heart attack can an EKG identify it?
DBug52 posted:
Christmas Eve (technically very early Christmas Day), I woke up with chest pains that seemed lower than my heart, but it had me doubled over. After reading WebMD, I worry I may have suffered a mild heart attack.

It's now late Christmas night and I'd like to do an EKG somewhere to see if that's what I suffered. How long after a potential attack can an EKG still be effective in identification? Can I have an EKG 36, 48 or even 72 hours later and still find something? Or is it too late?

If it's not too late, what can I look for in my Yellow Pages to find a business that offers EKG's cheaper than ERs or doctor visits? (I've heard them advertised, but the names escape me and I'm not sure how to look them up.)

CardiostarUSA1 responded:

"Can I have an EKG 36, 48 or even 72 hours later and still find something?"

Often yes, and even months/years later.

"What can I look for in my...."

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What happens during a heart attack?

During a heart attack, the heart's electrical conduction goes through a series of changes/abnormalities (as seen with an electrocardiogram, ECG).

Elevation of the ST segment is the hallmark abnormality of an acute MI. It occurs when the heart muscle is being injured by a lack of blood flow and oxygen and is also called "current of injury".

STEMI is an ST-elevation myocardial infarction, often referred to as a Q wave myocardial infarction and NSTEMI is a non-ST-elevation myocardial infarction, often referred to as a non-Q wave myocardial infarction.

If/when a Q wave develops after a heart attack or myocardial infarction (MI), it is called a Q wave MI, usually corresponding to a transmural MI, affecting the entire/full thickness of the heart muscle, the worst type (has a substantially higher mortality rate.

When a Q wave does not develop after an MI, it is called a non-Q wave MI, usually corresponding to non-transmural or a subendocardial MI, less damaging than a Q wave MI, as the heart muscle just under the sensitive inner lining of the heart is affected (lower mortality rate, though this type of incomplete MI poses a high risk for reinfarction, or completing the infarction).

WHAT HAPPENS AFTER A HEART ATTACK (and down the road) mainly depends on what specific area(s) of the heart muscle were damaged, size and depth of the damage, and if there has been any previous damage or other serious/severe heart condition(s) exist.

Cell/tissue death does not occur immediately (once the artery is 100% blocked, with no, or insufficient coronary artery collateral circulation). It takes several minutes to start the injury process, which then continues on (evolves, in phases) for several hours, unless the artery is opened up. restoring blood flow.

Prompt treatment
can limit the damage, but the damage that has been already done is permanent/irreversible (though some ongoing clinical trials are showing promise for making heart damage reversible).

After a completed heart attack, the body heals the heart damage caused by it by forming scar tissue. This healing process is usually complete in 4-8 weeks.



It is important to remember that EKGs are not 100% accurate. Normal recordings can be obtained in patients with significant heart disease, or some "abnormalities" may exist in the presence of a normal heart.

be proactive in your health/medical matters. Most important, communicate/interact well with your doctor(s).

Best of luck down the road of life.

Take care,


WebMD member (since 8/99)




Be a questioning patient. Talk to your doctor and ask questions. Studies show that patients who ask the most questions, and are most assertive, get the best results. Be vigilant and speak up!"

- Charles Inlander, People's Medical Society


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NEVER delay or disregard seeking professional medical advice from your physician or other qualified health provider because of something you have read on WebMD.

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