ICD-10 Coding for Myocardial Infarction with Coronary Stent Placement
For a patient with a history of myocardial infarction who has undergone coronary stent placement, you need to code both the type of MI and the procedural intervention using specific ICD-10-CM diagnosis codes and ICD-10-PCS procedure codes.
Primary Diagnosis Codes for Myocardial Infarction
The specific ICD-10-CM code depends on the type and timing of the MI:
Acute STEMI (ST-Elevation Myocardial Infarction)
- I21.0 - Acute transmural myocardial infarction of anterior wall 1
- I21.1 - Acute transmural myocardial infarction of inferior wall 1
- I21.2 - Acute transmural myocardial infarction of other sites
- I21.3 - Acute transmural myocardial infarction of unspecified site
- I21.9 - Acute myocardial infarction, unspecified (use when STEMI vs NSTEMI distinction is unclear) 1
Acute NSTEMI (Non-ST-Elevation Myocardial Infarction)
- I21.4 - Acute subendocardial myocardial infarction 1
Subsequent (Recurrent) Myocardial Infarction
- I22.0 - Subsequent myocardial infarction of anterior wall 1
- I22.1 - Subsequent myocardial infarction of inferior wall 1
- I22.8 - Subsequent myocardial infarction of other sites 1
- I22.9 - Subsequent myocardial infarction of unspecified site 1
Old/Healed Myocardial Infarction (History of MI)
- I25.2 - Old myocardial infarction (use for patients with a past history of MI, now healed)
Procedure Codes for Coronary Stent Placement
ICD-10-PCS codes for percutaneous coronary intervention with stent placement require specificity regarding the vessel treated:
Drug-Eluting Stent (DES) Placement
- 027034Z - Dilation of coronary artery, one artery, with drug-eluting intraluminal device, percutaneous approach
- 027134Z - Dilation of coronary artery, two arteries, with drug-eluting intraluminal device, percutaneous approach
- 027234Z - Dilation of coronary artery, three arteries, with drug-eluting intraluminal device, percutaneous approach
Bare-Metal Stent (BMS) Placement
- 027035Z - Dilation of coronary artery, one artery, with intraluminal device, percutaneous approach
- 027135Z - Dilation of coronary artery, two arteries, with intraluminal device, percutaneous approach
Critical Coding Considerations
The distinction between STEMI and NSTEMI is clinically crucial but challenging to capture accurately with ICD-10 codes alone 1. Research demonstrates that codes I21.0 through I21.3 best identify STEMI cases, while I21.4 identifies NSTEMI, though administrative coding has inherent limitations 1.
Timing-Based Coding Rules
- Use I21.x codes for the acute MI episode during the initial hospitalization and for 4 weeks following the event 2
- Use I22.x codes for subsequent MI occurring within 4 weeks of an initial MI 1
- Use I25.2 for encounters after the 4-week acute period when documenting history of MI 3
Common Coding Pitfalls to Avoid
Do not use I21.9 (unspecified acute MI) when the specific location or type is documented - this code has shown increasing use but reduces data quality 1. Always code to the highest level of specificity available in the medical record.
Ensure the stent type (drug-eluting vs bare-metal) is accurately documented and coded 2, 4. The American College of Cardiology guidelines specify that both DES and BMS are acceptable for STEMI, but the choice impacts long-term antiplatelet therapy requirements 2, 4.
Code any complications or comorbidities separately, including:
- Cardiogenic shock (R57.0)
- Acute heart failure (I50.x series)
- Coronary artery disease status (I25.10 for atherosclerotic heart disease)
Validation of Procedure Coding
Administrative data using ICD-10 and CCI codes can identify STEMI patients with 94% sensitivity and accurately define in-hospital cardiac procedures with kappa statistics of 0.83-1.00 3. However, always verify that the procedure code matches the actual intervention performed - percutaneous coronary intervention with stent placement has specific codes distinct from angiography alone or balloon angioplasty without stenting 3.