Understanding differences between stemi and nstemi

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Hello everyone!! I'm a nursing student and i'm having some difficulty with understanding the difference in stemi and nstemi with MI and ACS.

So, let me see if I can explain what I know and make sure its right

Acute Coronary Syndrome refers to any heart issue including MI and Unstable angina.

MI is when a coronary artery gets clogged/blocked and stops a part of the heart from getting oxygen causing it to stop working and/or cell death

Unstable Angina is chest pain that is caused by coronary blockage and is not relieved by resting.

If a PT is having Angina and is hooked up to an ECG to determine if its nstemi or stemi.

So... if the PT has nstemi the ST segment is obviously not elevated so its treated the same as unstable angina and... if its a stemi it's treated as a MI?

I think i'm just getting confused!!!. I'm sorry if it's just a wall of text but I can't seem to get a grasp on it to save my life!! I've tried to "google" and read other books but NOTHING is helping me here.

psu_213, BSN, RN

3,878 Posts

Specializes in Emergency, Telemetry, Transplant.

MI stands for myocardial infarction. Quite simply is is when a part heart muscle (the myocardium) dies as a result of a lack of oxygen (infarction). Infarction can occur anywhere in the body when blood supply is disrupted for some reason: brain infarction (stroke), a lung/pulmonary infarction (perhaps due to a PE), a kidney infarction, etc. etc.

STEMI stand for ST (segment) elevation myocardial infarction. A 12 lead EKG will reveal an elevation in the ST segment in some leads--which leads depends on which area of the heart muscle is infarcting (anterior, posterior, inferior, etc.). A STEMI is quite serious, possibly deadly, event. Most STEMIs are taken from the ER directly to the cath lab for (hopefully) reperfusion.

NSTEMI refers to non-ST elevation myocardial infarction. That is, parts of the heart muscle is infarcting without any ST elevations on the 12 lead EKG. Usually evidence of a NSTEMI is determined based on serial troponins (a cardiac enzyme). If there is any measurable amount of troponin in the blood, then heart muscle damage, of some sort, has occurred. In the absence of some other cause (PE, for instance, can cause a troponin elevation), NSTEMI is diagnosed. Some of these are managed medically, though most pts. with NSTEMI end up in the cath lab at some point, though usually not as emergently as with STEMI.

Point is, both are MIs and both are serious events. The only real difference between the 2 is the EKG "signatures" of each.

Anyway, that is the short version...I'm sure someone can add more to this.

Here is a website I found that could be helpful:


Esme12, ASN, BSN, RN

1 Article; 20,908 Posts

Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

Esme12, ASN, BSN, RN

1 Article; 20,908 Posts

Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

They are both ACS....

Acute coronary syndrome (ACS), a common complication of coronary heart disease, is associated with more than 2.5 million hospitalizations worldwide each year. Most cases of ACS are caused by rupture of an atherosclerotic plaque in a coronary artery, resulting in the formation of a thrombus, which can restrict the flow of blood to the heart muscle. The degree of arterial blockage caused by the thrombus determines the amount of myocardial damage that occurs and the type of ACS that results. The main methods used to confirm a diagnosis of ACS and identify the type of ACS include electrocardiogram (ECG) and cardiac troponins. Acute phase treatment of ACS includes a combination of anti-ischaemic and antithrombotic agents.
Acute Coronary Syndrome (ACS)
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