Q&A: ICD-10-CM documentation for reporting acute MI
Q: We are having trouble determining what qualifies a patient as having an acute myocardial infarction (MI) and what documentation would support the diagnosis. Can you help our coding team clarify?
A: Yes. It’s important for coders to understand that the term acute MI (found in ICD-10-CM category I21.-) should be used when there is documented evidence of myocardial necrosis in a clinical setting consistent with acute myocardial ischemia.
Under these conditions any one of the following clearly documented criteria is needed to meet the diagnosis for MI:
- Detection of a rise and/or fall of a cardiac biomarker, preferably troponin, above the 99th percentile of the upper reference limit of normal and at least 1 of the following:
- Development of pathological Q waves in the ECG
- Identification of an intracoronary thrombus by angiography or autopsy
- Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality
- New or presumed new significant ST-segment—T wave (ST-T) changes or new left bundle branch block
- Symptoms of ischemia
Once the presence of acute MI has been clearly established, there are several types of acute MI which should be thoroughly documented in the patient’s record before corresponding diagnosis codes can be reported. They include:
1. Spontaneous MI
2. MI due to an ischemic imbalance of oxygen supply and demand
3. MI resulting in death when biomarkers are not available
4a. MI related to percutaneous coronary intervention
4b. MI related to stent thrombosis
5. MI related to coronary artery bypass graft surgery
Also, a “recent MI” should be noted in the documentation if a previous MI occurred within the prior 28 days.
Editor’s note: This answer was adapted from the myocardial infarction pocket card from JustCoding’s Inpatient Documentation Pocket Cards.