What ICD‑10 codes are appropriate for documenting long‑term aspirin use and a personal history of myocardial infarction?

ICD-10 Coding for Aspirin Use and History of Myocardial Infarction

For documenting long-term aspirin therapy in a patient with a history of myocardial infarction, use ICD-10 code Z79.82 (Long-term [current] use of aspirin) combined with Z86.718 (Personal history of other venous thrombosis and embolism) or the more specific I25.2 (Old myocardial infarction) to capture the historical MI.

Primary Coding Approach

For Long-Term Aspirin Use

• Z79.82 is the appropriate ICD-10 code for documenting long-term (current) use of aspirin as secondary prophylaxis 1
• This code should be used when aspirin is prescribed for ongoing cardiovascular disease prevention following MI 2

For History of Myocardial Infarction

• I25.2 (Old myocardial infarction) documents a healed MI when the patient is beyond the acute phase 1, 2
• This code has high validity with positive predictive values exceeding 80% when used in the principal diagnosis position 1
• Z86.718 can serve as an alternative code for personal history of cardiovascular events, though I25.2 is more specific for MI 3

Clinical Context for Coding

Aspirin Dosing Standards

• Post-MI patients should receive 75 mg aspirin daily for long-term secondary prevention 4
• During acute MI, initial dosing is 150 mg daily for one month, then reduced to 75 mg for maintenance 4
• The evidence strongly supports continued aspirin therapy indefinitely after MI, with recommendations for lifelong use 4

Timing Considerations

• After the first month post-MI, patients transition from acute MI management (I21.* codes) to chronic management with I25.2 2
• Long-term aspirin adherence significantly reduces risk of recurrent MI, stroke, or death, particularly in the first 4 years post-MI 5
• The absolute risk reduction is highest at 2-4 years after MI (8.34% vs 10.72% for non-adherent patients) 5

Important Coding Pitfalls

Avoid These Common Errors

• Do not use acute MI codes (I21.* or I22.*) for patients with remote history of MI, as these are reserved for current acute events 1, 2
• ICD-10 codes in secondary diagnosis positions have lower positive predictive values (55.8%) compared to principal diagnosis positions (86.8%) 1
• Unspecified MI codes have significantly lower validation rates and should be avoided when the history is clear 6

Code Validation Considerations

• ICD-10-CM codes for MI have demonstrated PPV of approximately 80% overall in U.S. healthcare systems 1
• ICD-10 codes specifically have shown 100% PPV in best-case scenarios, superior to ICD-9-CM codes 3
• The 2015 transition to ICD-10-CM did not substantially change the proportion of patients identified with MI 2

Supporting Documentation Requirements

Essential Clinical Information

• Document the specific date of the prior MI to justify I25.2 coding 2
• Record aspirin dose (typically 75 mg daily for maintenance) to support Z79.82 4
• Note any contraindications or intolerance to aspirin, as this affects coding appropriateness 7
• Include comorbidities such as hypertension, coronary atherosclerosis, or congestive heart failure, which commonly co-occur and affect risk stratification 1, 2

Age and Sex Considerations

• Aspirin effectiveness for secondary prevention after MI is well-established in men aged 45-79 years 8
• In patients >65 years, particularly women, the benefit-risk profile may differ, though this does not change the coding approach 5