Don’t Get Clogged Up When Coding Atherosclerosis in ICD-10

Thu, Feb 4, 2016 --


Atherosclerosis ICD-10 Coding

The term atherosclerosis refers to hardening of the arteries, or arteriosclerosis, that includes a buildup of fatty plaque deposits on arterial walls. This blood vessel blockage limiting oxygenation of body tissue can result in coronary artery disease.

Review This Atherosclerosis Coding Example

Let’s take a look at documentation for a patient scenario and consider what ICD-10 codes would apply.

Mrs. M was discharged from the hospital to home with home health care following an acute inferior wall myocardial infarction (MI) two weeks previously. She is still being monitored for her first MI and for a new non-ST elevation myocardial infarction (NSTEMI) one week earlier and continues to have atrial fibrillation.

You work for a home health agency hired to provide observation and assessment of her unstable angina and CAD. Your organization will also be responsible for providing education about her new cardiac medications. Mrs. M is not a surgical candidate. How would you code for her in ICD-10?

Here’s How You’d Code in This Case

In ICD-10, your coding for this patient would be:

  • I25.110, Atherosclerotic heart disease of native coronary artery with unstable angina pectoris;
  • I21.19, ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall;
  • I22.2, Subsequent non-ST elevation (NSTEMI) myocardial infarction;
  • I48.91, Unspecified atrial fibrillation; and
  • Z79.899, Other long term (current) drug therapy.

Note that in this scenario, we’ve reported Mrs. M’s coronary artery disease (CAD) first. These ICD-10 codes indicate both CAD and the presence or absence of angina, which is a new assumption in ICD-10; you can assume a causal relationship in a patient with both atherosclerosis and angina pectoris, unless the documentation indicates the angina is due to something other than the atherosclerosis.

Next, list the patient’s acute MIs, but don’t forget the new four-week guidelines for reporting acute MIs. ICD-10’s cardiology coding guidelines advise sequencing I22 and I21 “on the circumstances of the encounter.” Since the STEMI in this scenario is the more serious MI, list it first.

ICD-10 breaks from ICD-9 in the definition of the term “subsequent.” In ICD-9, “subsequent” means caring for the patient in the subsequent health care setting of the eight-week acute period, including post-acute home health and hospice care. However, in ICD-10, “subsequent” refers to the MI itself, specifically an MI occurring after the initial MI, within the four-week definition of an acute myocardial infarction.

Report the patient’s atrial fibrillation and her medications later in your list of diagnosis codes.

Got ICD-10 Tips?

I was talking to a coder friend today, and we agreed that we think the conversion went well because coders were so well prepared. How about you? Do you have any ICD-10 coding tips to share? Let us know in the comment box below. We love to hear from you!

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Susan taught health information and healthcare documentation at the community college level for more than 20 years. She has a special love for medical language and terminology. She is passionate about ensuring accurate patient healthcare documentation through education. She has a master's degree in healthcare administration, is a certified healthcare documentation specialist, and serves as immediate past president for the Association for Healthcare Documentation Integrity (AHDI).

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