Myocardial infarction (MI) is a common cardiovascular disease and a leading cause of death worldwide. MI has different classification methods, which can be classified according to the disease phase, infarction location, electrocardiogram (ECG) expression, clinical type, clinical manifestation and coronary stenosis.

External IDs:
Disease Ontology DOID:5844	ICD11 BA41
OMIM 608446	SNOMED-CT 22298006
KEGG H01730	MedGen C1832662 C1838021 C3277063
MalaCards MYCoo7	EFO EFO_0000612
MeSH D009203	NCIt C27996

(1) Acute MI (AMI): the term acute myocardial infarction (MI) should be used when there is evidence of myocardial necrosis in a clinical setting consistent with acute myocardial ischemia. Under these conditions any one of the following criteria meets the diagnosis for MI; Detection of a rise and/or fall of cardiac biomarker values with at least one value above the 99th percentile upper reference limit (URL ) and with at least one of the following; a. Symptoms of ischaemia. b. New or presumed new significant ST-segment-T wave (ST-T) changes or new left bundle branch block (LBBB). c. Development of pathologic Q waves in the ECG. d. Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality. e. Identification of an intracoronary thrombus by angiography or autopsy. Infarction of any myocardial site, occurring within 4 weeks (28 days) from onset of a previous infarction (WHO) (PMID 29083808; ICD11 BA41);

(2) Old MI (OMI): also known as healed MI, prior MI or previous MI. Past MI diagnosed by ECG or other special investigation, but currently presenting no symptoms (PMID 30153967; ICD11 BA50);

(3) Recurrent MI: incident MI is defined as the individual's first MI. When features of MI occur in the first 28 days after an incident event, the second event is not counted as a new MI for epidemiological purposes. If characteristics of MI occur after 28 days following an incident MI, it is considered to be a recurrent MI (PMID 30571511).

(4) Re-infarction: the term re-infarction is used clinically for an acute MI that occurs within 28 days of an incident or recurrent MI (PMID 30571511).

(1) Anterior MI: a MI with abnormal Q waves or QS waves in most of the chest leads (V1 ~ V5). It includes anterior, anteroapical, anterolateral, and anteroseptal MI (PMID 13463910; ICD11 BA41.Z);

(2) Inferior MI: a MI with abnormal Q waves or QS waves in leads II, III, and aVF in the ECG. It includes diaphragmatic wall, inferior, inferolateral, and inferoposterior (PMID 29262146; ICD11 BA41.Z; Disease Ontology DOID:5850);

(3) MI of other sites: including apical-lateral, basal-lateral, high lateral, lateral, posterior, posterobasal, posterolateral, posteroseptal, and septal MI (ICD11 BA41.Z).

(1) ST elevation MI (STEMI): an MI with developing ST elevation in two contiguous leads. (PMID 30335314; ICD11 BA41.0);

(2) Non-ST elevation MI (NSTEMI): an MI without developing ST elevation in ECG. (PMID 30020600; ICD11 BA41.1);

(1) Type 1 MI: a spontaneous MI caused by plaque erosion and/or rupture, fissuring, or dissection (PMID 30571511);

(2) Type 2 MI: a MI related to ischemia, such as coronary palsy, anemia, arrhythmia,respiratory failure, high blood pressure or hypotension (PMID 30571511);

(3) Type 3 MI: sudden cardiac death. A MI with ST-T wave changes in ECG, new complete left bundle branch block or coronary angiography or autopsy confirmed fresh thrombus, but without evidence of enzymology (PMID 30571511);

(4) Type 4 MI: a MI related with coronary angioplasty or stents;

1) Type 4a MI: a MI related with percutaneous coronary intervention (PCI). Stand-alone post-procedural increases of cTn values are sufficient to establish a diagnosis of procedural myocardial injury but not for the diagnosis of type 4a MI. Type 4a MI requires an elevation of cTn values greater than five times the 99th percentile URL in patients with normal baseline values or, in patients with elevated pre-procedure cTn in whom the cTn levels are stable (≤20% variation) or falling, the post-procedure cTn must rise >20% to an absolute value more than five times the 99th percentile URL. In addition, there should be evidence of new myocardial ischaemia, either from ECG changes, imaging evidence, or from procedure-related complications associated with reduced coronary blood flow such as coronary dissection, occlusion of a major epicardial artery or a side branch occlusion/thrombus, disruption of collateral flow, slow flow or no-reflow, or distal embolization (PMID 30571511) ;

2)Type 4b MI: a subcategory of PCI-related MI is stent/scaffold thrombosis, type 4b MI, as documented by angiography or autopsy using the same criteria utilized for type 1 MI. It is important to indicate the time of the occurrence of the stent/scaffold thrombosis in relation to the timing of the PCI procedure. The following temporal categories are suggested: acute, 0 to 24 h; subacute, >24 h to 30 days; late, >30 days to 1 year; and very late >1 year after stent/scaffold implantation (PMID 30571511);

3)Type 4c MI: occasionally MI occurs and—at angiography, in-stent restenosis, or restenosis following balloon angioplasty in the infarct territory—is the only angiographic explanation since no other culprit lesion or thrombus can be identified. This PCI-related MI type is designated as type 4c MI, defined as focal or diffuse restenosis, or a complex lesion associated with a rise and/or fall of cTn values above the 99th percentile URL applying, the same criteria utilized for type 1 MI (PMID 30571511);

(5)Type 5 MI: a MI related with coronary artery bypass grafting (CABG) (PMID 30571511).

(1) Silent MI (SMI): a history of MI in the absence of clinical symptoms and positive electrocardiographic findings. Silent MI is related to mitral valve insufficiency and congestive heart failure. An important gene associated with silent MI is TNNT2 (Troponin T2, Cardiac Type), and among its related pathways/superpathways are Dilated cardiomyopathy (DCM) and Embryonic and Induced Pluripotent Stem Cells and Lineage-specific Markers. The drugs Cobalt and Chromium have been mentioned in the context of this disorder. Affiliated tissues include heart, kidney and brain (MalaCards SLNoo1; NCIt C35400; PMID 29301632).

(2) Clinical MI (CMI): Clinical infarct refers to those subjects who complained of symptoms suggestive of heart disease and who in addition had at least one of the following (PMID 1127069):

a. ECG showing signs of probable or possible infarct. (cf. criteria in previous publication.

b. Autopsy findings showing evidence of recent MI and/or coronary thrombosis.

c. A composite of clinical, laboratory and ECG diagnosis in subjects who were hospitalized and in whom the composite picture of clinical signs and symptoms, changes in laboratory findings (transaminase, sedimentation rates, leucocytes, etc.) and ECG ischemic changes, together, led to the diagnosis of probable MI.

d. Sudden death, i.e. death occurring within 1 hr of onset of symptoms in a person who was not hospitalized or confined to bed. In other words, it was an unexpected death. Autopsy studies have shown that the majority of these are due to MI.

(1) MI with nonobstructive coronary arteries (MINOCA): it remains a puzzling clinical entity that is characterized by clinical evidence of MI with normal or near-normal coronary arteries on angiography (stenosis <50%) (ICD-11 BA41.Z; PMID 30571511).