Answer:

 

D. I21.A1, I21.11

First of all, it’s important to know what these acronyms stand for:

  • STEMI is the acronym for an ST elevation myocardial infarction. 
  • MI is short for myocardial infarction and is also known as a heart attack.

The documentation indicates that both myocardial infarctions (MIs) were treated within 4 weeks of each other. The first MI was a type I STEMI with right coronary artery involvement, and the second one was a type 2 MI. 

Locate and Verify

Type 1 STEMI

In the ICD-10-CM coding manual Index, look under Infarct, infarction/myocardium, myocardial (acute) with stated duration of 4 weeks or less/ST elevation (STEMI), involving coronary artery of right coronary artery I21.11.

This code can be verified in the Tabular as:

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

I21.11 is also reportable when documentation states, “Inferoposterior transmural (Q wave) infarction (acute).”

Be sure to review the “Includes,” “Excludes2,” and “Use Additional” notes before making your final coding selections.

For example, there is an “Includes” note at I21 that reads:

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 stated duration of 4 weeks (28 days) or less from onset

The “Use additional” note provided at I21.11 states an additional code should be assigned to identify:

  • exposure to environmental tobacco smoke (Z77.22)
  • history of tobacco dependence (Z87.891)
  • occupational exposure to environmental tobacco smoke (Z57.31)
  • status post administration of tPA (rtPA) in a different facility within the last 24 hours prior to admission to current facility (Z92.82)
  • tobacco dependence (F17.-)
  • tobacco use (Z72.0)

There is also a “Use additional” note provided at I20-I25 that indicates a code should be used to identify presence of hypertension (I10-I16).

Some of the conditions listed at the “Excludes2” note at I21.11 are:

  • old myocardial infarction (I25.2)
  • postmyocardial infarction syndrome (I24.1)
  • subsequent type 1 myocardial infarction (I22.-)

There is also an “Excludes2” note at I00-I99, which should be reviewed and coded if applicable.

Type 2 MI

In the coding manual Index, look under Infarct, infarction/myocardium, myocardial (acute) with stated duration of 4 weeks or less/ST elevation (STEMI), type 2  I21.A1.

This code can be verified in the Tabular as:

I21.A1, Myocardial infarction type 2

Other clinical terms reportable with I21.A1 include:

  • Myocardial infarction due to demand ischemia
  • Myocardial infarction secondary to ischemic imbalance

Again, make sure to review the “Code First,” “Includes,” “Use Additional,” and “Excludes2” notes.

The “Code First” note indicates that the underlying cause should be sequenced first, such as:

  • anemia (D50.0-D64.9)
  • chronic obstructive pulmonary disease (J44.-)
  • paroxysmal tachycardia (I47.0-I47.9)
  • shock (R57.0-R57.9)

Just like for the “Use additional” note provided at code I21.11, the following should be assigned here, when applicable, to identify:

  • exposure to environmental tobacco smoke (Z77.22)
  • history of tobacco dependence (Z87.891)
  • occupational exposure to environmental tobacco smoke (Z57.31)
  • status post administration of tPA (rtPA) in a different facility within the last 24 hours prior to admission to current facility (Z92.82)
  • tobacco dependence (F17.-)
  • tobacco use (Z72.0)
  • presence of hypertension (I10-I16).

The “Excludes2” notes are the same for this code as they are for I21.11. If the patient has any of the listed conditions, they will also need to be coded.

Sequencing

Sequencing of these two codes, according to the ICD-10-CM Official Guidelines for Coding and Reporting (FY 2020), is based on the circumstances of the encounter. 

The reason for the second admission was the type 2 MI, which occurred less than 4 weeks after the first MI. Therefore, the type 2 MI (I21.A1) is sequenced first, followed by the type 1 MI (I21.11).

The second MI is not considered a “subsequent” MI, because the coding guidelines state that subsequent MIs are only assigned when both MIs are type 1. (A subsequent MI is then coded to category I22.) In this case, we have one type 1 and one type 2.

A, B, and C are incorrect. 

I22.2 refers to Subsequent non-ST elevation (NSTEMI) myocardial infarction. (A)

I25.2 is for Old myocardial infarction. (B, C)

And that’s all, folks!

How Did You Do?

Coding for acute myocardial infarctions can be tricky. But if you know the things to look for in the documentation, it definitely cuts down on the errors.

Things to look for include the location (which wall), arteries affected, whether it is an initial AMI (up to 4 weeks) or a subsequent AMI (AMI occurring within 4 weeks of initial AMI), and the type of AMI.

Also, documentation should include any tobacco use, dependence, and exposure when possible and should be assigned as secondary codes. Post administration of tPA (rtPA) prior to admission and within the previous 24 hours should also be documented and coded, as should any hypertension. If there are any questions, be sure to query the physician.


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