Acute myocardial infarction is divided into two categories ST elevation myocardial infarction (STEMI) and non ST elevation myocardial infarction (NSTEMI) in ICD 10 coding. These ICD 10 codes identify the sites for acute myocardial infarction. For STEMI, subcategories I21.0-I21.2 and code I21.3 are used and NSTEMI and nontransmural MIs, subcategory I21.4 is used.

Coding for Acute and Old myocardial infarction

For encounter of myocardial infraction which is equal to or less than four weeks old, in the acute or post acute setting and the patient is in continuous care for myocardial infarction. In such case codes from category I21 can be used. After 4 weeks of time if the patient is still receiving the care related to myocardial infarction, then an appropriate ICD 10 code for aftercare should be used, rather than an I21 category code. Now, for old myocardial infarction which does not require any further care, ICD 10 code I25.2 should be used.

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For unspecified acute myocardial infarction, use ICD 10 code I21.3. This is a default ICD 10 code for acute myocardial infarction, unspecified.

Subsequent acute myocardial infarction is coded from ICD 10 category I22. A code from category I22, Subsequent ST elevation (STEMI) and non ST elevation (NSTEMI) myocardial infarction, is to be used when a patient who has suffered an AMI has a new AMI within the 4-week time frame of the initial AMI. A code from category I22 must be used in conjunction with a code from category I21. The sequencing of the I22 and I21 codes depends on the circumstances of the encounter.

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List of ICD 10 codes for Myocardial infarction

I21  ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction

 This category includes cardiac infarction, coronary artery embolism, coronary artery occlusion, coronary artery rupture, coronary artery thrombosis, infarction of heart, myocardium or ventricle, myocardial infarction specified as acute or with a duration of 4 weeks (28 days) or less from onset.

I21.01 ST elevation (STEMI) myocardial infarction involving left main coronary artery

I21.02 ST elevation (STEMI) myocardial infarction involving left anterior descending coronary artery

I21.09 ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall

I21.1 ST elevation (STEMI) myocardial infarction of inferior wall

I21.11 ST elevation (STEMI) myocardial infarction involving right coronary artery

I21.19 ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall

Acute transmural myocardial infarction of inferior wall
Inferolateral transmural (Q wave) infarction (acute)
Transmural (Q wave) infarction (acute) (of) diaphragmatic wall
Transmural (Q wave) infarction (acute) (of) inferior (wall) NOS

I21.2 ST elevation (STEMI) myocardial infarction of other sites

I21.21 ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery

I21.29 ST elevation (STEMI) myocardial infarction involving other sites

I21.4 Non-ST elevation (NSTEMI) myocardial infarction

I22 Subsequent ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction

I22.0 Subsequent ST elevation (STEMI) myocardial infarction of anterior wall

I22.1 Subsequent ST elevation (STEMI) myocardial infarction of inferior wall

I22.8 Subsequent ST elevation (STEMI) myocardial infarction of other sites

I22.9 Subsequent ST elevation (STEMI) myocardial infarction of unspecified site

I23 Certain current complications following ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction (within the 28 day period)

I23.1 Atrial septal defect as current complication following acute myocardial infarction

I23.2 Ventricular septal defect as current complication following acute myocardial infarction

I23.3 Rupture of cardiac wall without hemopericardium as current complication following acute myocardial infarction

I23.4 Rupture of chordae tendineae as current complication following acute myocardial infarction

I23.5 Rupture of papillary muscle as current complication following acute myocardial infarction

I23.6 Thrombosis of atrium, auricular appendage, and ventricle as current complications following acute myocardial infarction

I23.7 Postinfarction angina

I23.8 Other current complications following acute myocardial infarction

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