Cardiology Coding Alert

You may need an aftercare code between acute and old for ICD-10.

Once ICD-10 is implemented, sticking to ICD-9's myocardial infarction coding rules is a sure path to inaccurate coding. To fully understand when to use the codes for an "old" myocardial infarction, take a careful look at the number of weeks listed in the definitions of acute diagnoses.

ICD-9-CM Code:

• 412, Old myocardial infarction

ICD-10-CM Code:

• I25.2, Old myocardial infarction

Often called a heart attack, myocardial infarction (MI) refers to an event in which the heart's blood supply is cut off, leading to a lack of oxygen and muscle death.

ICD-9 coding rules: Code 412 applies to a healed MI or a "past myocardial infarction diagnosed by ECG [EKG] or other special investigation, but currently presenting no symptoms." If the MI is less than 8 weeks old, you instead use a code from 410.xx (Acute myocardial infarction). For instance, 410.02 (Acute myocardial infarction; of anterolateral wall; subsequent episode of care) applies when the patient presents for evaluation after the initial episode of care if the MI is less than eight weeks old.

ICD-10 changes: ICD-10 offers similar notes about included diagnoses with I25.2, indicating the code is appropriate for a healed MI or "Past myocardial infarction diagnosed by ECG or other investigation, but currently presenting no symptoms."

However, ICD-10 has a four-week rule. Acute MI range I21.-- (ST elevation [STEMI] and non-ST elevation [NSTEMI] myocardial infarction) applies to "myocardial infarction specified as acute or with a stated duration of 4 weeks (28 days) or less from onset." An aftercare code would be appropriate "for encounters after the 4 week time frame [when] the patient is still receiving care related to the myocardial infarction," according to ICD-10-CM Official Guidelines (www.cdc.gov/nchs/data/icd10/10cmguidelines2012.pdf). You'll swap to I25.2 for healed MIs that no longer require care.

Documentation: When ICD-10 becomes effective, your clinician's documentation to indicate an old MI won't need to change much. Be sure there's space in the documentation or on the superbill to indicate how long ago the MI occurred and whether it's still being treated. Also alert clinicians that documentation of the conditions in the "use additional code" note will help you code more accurately (see below).

Coder tips: For ischemic heart diseases (I20-I25), you should use an additional code to identify presence of hypertension (I10-I15). ICD-10 also applies the note below to I25.2 as part of the chronic ischemic heart disease range (I25).

Use additional code to identify:

• Chronic total occlusion of coronary artery (I25.82)
• Exposure to environmental tobacco smoke (Z77.22)
• History of tobacco use (Z87.891)
• Occupational exposure to environmental tobacco smoke (Z57.31)
• Tobacco dependence (F17.-)
• Tobacco use (Z72.0).

Remember: When ICD-10-CM goes into effect, you should apply the code set and official guidelines in effect for the date of service reported. Learn more at www.cms.gov/ICD10/ and www.cdc.gov/nchs/icd/icd10cm.htm#10update. HHS Secretary, Kathleen Sebelius, issued a press release proposing the delayed implementation date Oct. 1, 2014. The comment period is now closed, and public comments are being reviewed and analyzed. The department is expected to issue the final rule soon.