MI Means Myocardial Infarction — the Medical Term for a Heart Attack
In cardiology and general hospital records, MI most commonly stands for myocardial infarction, which means a heart attack. It describes injury and death of heart-muscle tissue after blood flow to part of the heart is cut off long enough to deprive it of oxygen.
The abbreviation can appear in emergency notes, discharge summaries, problem lists and cardiology records. If MI appears next to current chest discomfort, shortness of breath, sweating, nausea or other possible heart-attack symptoms, treat the symptoms as an emergency rather than trying to decode the record at home.
From abbreviation to plain English
MI
The abbreviation seen in a medical record.
Myocardial infarction
The full medical term.
Heart attack
The common plain-language name.
Emergency boundary: a suspected heart attack needs immediate medical assessment. If you or someone else has new chest pressure or pain, shortness of breath, pain spreading to the arm, back, neck or jaw, unexplained sweating, nausea, marked weakness or other concerning symptoms, call your local emergency number. Do not wait for an online definition to confirm an MI.
What does MI mean in medical terms?
MI most commonly means myocardial infarction in cardiology and general medical records. Myocardial infarction is the medical term for a heart attack. The National Library of Medicine’s MedGen database lists “MI – myocardial infarction” as a synonym for myocardial infarction, and MedlinePlus lists heart attack as also called MI or myocardial infarction.
MI
Myocardial infarction
Heart attack
Cardiovascular medicine / cardiology
D009203 for Myocardial Infarction
An acute or suspected MI is a medical emergency.
Short abbreviations can be reused in different specialties, so the full note still matters.
October 5, 2026
What does “myocardial infarction” actually mean?
The full term becomes easier to understand when it is separated into its two ideas. Myocardial refers to the myocardium, the muscular tissue of the heart. Infarction refers to tissue death caused by loss of blood supply. NLM’s MeSH definition describes myocardial infarction as necrosis of the myocardium caused by obstruction of the blood supply to the heart.
Myocardial
Relating to the heart muscle, or myocardium.
Infarction
Death of tissue after its blood supply is interrupted long enough to cause irreversible injury.
Myocardial infarction
Heart-muscle injury and death caused by an interruption of blood flow to part of the heart.
Plain-language translation: MI is not simply “chest pain.” It refers to actual heart-muscle injury. Chest pain can have many causes, and some heart attacks occur with mild symptoms or without typical chest pain.
How MI may appear in a medical record
MI is often written as part of a longer phrase. The nearby words can tell you whether the note is describing a current event, a previous heart attack or a specific electrocardiogram pattern. The abbreviation alone does not tell you when the event occurred or how severe it was.
| Record wording | Usual meaning | What it does not tell you by itself |
|---|---|---|
| MI | Myocardial infarction / heart attack in a cardiology or general hospital context. | Timing, type, artery involved, severity or current treatment. |
| Acute MI / AMI | Acute myocardial infarction, meaning a current or recent heart attack diagnosis. | The exact MI type and treatment plan. |
| History of MI | The record indicates a previous myocardial infarction. | The exact date, location or amount of heart damage unless the chart gives those details. |
| STEMI | ST-elevation myocardial infarction, a recognized MI category associated with persistent ST-segment elevation on ECG plus evidence of myocardial injury. | The complete anatomy, cause and procedure plan. |
| NSTEMI | Non-ST-elevation myocardial infarction, an MI that does not show ST-segment elevation on the ECG. | The degree of artery blockage or overall risk from the abbreviation alone. |
Abbreviation caution: MI is strongly associated with myocardial infarction in cardiology, but two-letter abbreviations can be ambiguous outside their usual specialty. If the surrounding note does not clearly refer to the heart, ask the clinician or records department what MI means in that specific document.
STEMI and NSTEMI are both myocardial infarctions
Two labels commonly seen with MI are STEMI and NSTEMI. NLM MeSH defines STEMI as a myocardial infarction with persistent ST-segment elevation on the electrocardiogram and release of biomarkers of heart-muscle injury. NSTEMI is a myocardial infarction without ST-segment elevation on the ECG.
STEMI
ST-elevation myocardial infarction. The ECG shows persistent ST-segment elevation, and cardiac biomarkers support myocardial injury. This distinction affects urgent treatment decisions.
NSTEMI
Non-ST-elevation myocardial infarction. The ECG does not show ST-segment elevation, but the clinical picture and cardiac biomarkers can still establish an MI.
Do not use the acronym to judge severity yourself. Both STEMI and NSTEMI require medical evaluation. Doctors interpret symptoms, ECG findings, troponin results and the overall clinical situation together.
Why ECG and troponin are often mentioned next to MI
When a heart attack is suspected, an electrocardiogram (ECG or EKG) is one of the first tests used to look for electrical changes in the heart. Blood testing for troponin looks for proteins released when heart-muscle cells are injured. NHLBI notes that troponin tests may be repeated over time because a changing pattern can help clinicians determine whether an MI has occurred.
Symptoms and history
The team asks about chest discomfort and other symptoms, timing, medical history and risk factors. Symptoms alone do not prove or exclude MI.
ECG / EKG
The ECG looks for changes that can support an acute MI diagnosis and helps distinguish patterns such as STEMI from presentations without ST elevation.
Troponin blood tests
Troponin is a key biomarker of heart-muscle injury. Results are interpreted with symptoms, ECG findings and changes over time rather than as a stand-alone internet diagnosis.
Additional testing when needed
Clinicians may use imaging, coronary angiography or other tests depending on the presentation and what they need to clarify.
MI, angina and cardiac arrest are not the same thing
| Term | What it means | Relationship to MI |
|---|---|---|
| Myocardial infarction (MI) | Heart-muscle injury and tissue death caused by interrupted blood flow. | This is the medical condition abbreviated MI. |
| Angina | Chest pain or pressure caused by reduced blood and oxygen supply to heart muscle. | Angina is not automatically an MI; clinicians assess whether heart-muscle injury has occurred. |
| Cardiac arrest | The heart suddenly stops pumping effectively. | A heart attack and cardiac arrest are different events, although a heart attack can trigger cardiac arrest. |
When MI symptoms need emergency help
Heart-attack symptoms do not always begin as sudden, crushing chest pain. NHLBI and MedlinePlus note that symptoms can be mild, can come and go, and can include chest discomfort, shortness of breath, discomfort in other parts of the upper body, sweating, nausea, dizziness or unusual fatigue. Some people can have very mild symptoms or a silent heart attack.
Chest or breathing symptoms
Pressure, squeezing, fullness or pain in the chest; shortness of breath; or discomfort that does not feel normal for you.
Pain that spreads
Discomfort may involve one or both arms, the back, shoulders, neck, jaw or upper abdomen.
Other warning signs
Cold sweat, nausea, vomiting, lightheadedness, dizziness, rapid or irregular heartbeat or unusual fatigue can occur.
Do not wait for certainty. If a heart attack is possible, call your local emergency number. MedlinePlus advises not to drive yourself to the hospital and not to wait to see whether symptoms disappear.
Why an acute MI is treated quickly
During an MI, prolonged loss of oxygen-rich blood can cause more heart-muscle damage. Emergency treatment is aimed at limiting that damage and restoring blood flow when possible. NHLBI describes treatment that may include medicines and procedures such as percutaneous coronary intervention (PCI, also called coronary angioplasty), depending on the type of heart attack and the patient’s condition.
This terminology page does not tell an individual which medicine or procedure they need. If MI is suspected, treatment decisions belong to the emergency and cardiology team because the safest approach depends on the ECG, troponin results, bleeding risk, coronary anatomy and other clinical factors.
After an MI: recovery may include prescribed medicines, follow-up care and cardiac rehabilitation. NHLBI describes cardiac rehabilitation as a medically supervised program that can include exercise training, heart-health education and counseling.
Authoritative sources used for this MI definition
MI medical abbreviation FAQs
What does MI stand for in medical terms?
In cardiology and general medical records, MI most commonly stands for myocardial infarction, the medical term for a heart attack.
Is MI the same as a heart attack?
Yes when MI means myocardial infarction. “Heart attack” is the common-language name; “myocardial infarction” is the medical term.
What does acute MI mean?
Acute MI means acute myocardial infarction, referring to a current or recent heart attack diagnosis that requires urgent medical care.
What is the difference between STEMI and NSTEMI?
Both are myocardial infarctions. STEMI has persistent ST-segment elevation on ECG, while NSTEMI does not show ST-segment elevation. Doctors use ECG findings, cardiac biomarkers such as troponin and the overall clinical picture to diagnose and manage them.
What does “history of MI” mean?
It usually means the medical record documents a previous myocardial infarction or heart attack. The phrase by itself does not state the exact date or amount of heart damage.
How do doctors test for an MI?
Evaluation commonly includes an ECG/EKG and blood tests for troponin, along with symptoms, medical history and examination. Troponin may be measured more than once to look for changes over time.
Is MI the same as cardiac arrest?
No. An MI is a heart attack caused by interrupted blood flow that damages heart muscle. Cardiac arrest is when the heart suddenly stops pumping effectively. A heart attack can sometimes trigger cardiac arrest.
Can MI have another meaning?
Short medical abbreviations can be ambiguous across specialties. MI is strongly associated with myocardial infarction in cardiology and general hospital use, but the surrounding words and specialty should still be checked before interpreting an unfamiliar record.
What should I do if I have possible heart-attack symptoms?
Call your local emergency number immediately. Do not wait for an online abbreviation guide to confirm the diagnosis, and do not drive yourself if emergency medical transport is available.
How to use this MI definition safely
This page explains medical terminology; it does not diagnose a heart attack from symptoms, ECG results or blood tests. If MI appears in your own record, a clinician can explain whether it refers to an active event, a previous heart attack, a suspected diagnosis or another specialty-specific use.
Source review: the abbreviation, MeSH code, standardized synonyms, heart-attack definition, symptom guidance and diagnostic context were checked against current NLM/NCBI, MedlinePlus and NHLBI resources during this October 5, 2026 refresh.