What’s with all the new codes
for myocardial infarctions (MI), you may be asking yourself. What differentiates a type 1 from a type 2 MI? This edition of “In the kNOW” will
delve into those questions and more.
As you have undoubtedly noticed, myocardial infarction codes now allow us to capture the “type” of MI that the patient experiences. This is very useful as more and more cardiologists had been specifically documenting type 2 MI and leaving us with no way to distinguish that particular type of MI from any other. 1st Qtr. 2017 Coding Clinic had instructed coders to use I21.4 for a type 2 MI which was the same code as a Non-ST elevation myocardial infarction. We were instructed to assign the type 2 to NSTEMI unless there was documentation that the MI was a STEMI. Now, however, we have a specific code, I21.A1, to assign when a patient has suffered a type 2 MI, regardless of whether they are specified as STEMI or NSTEMI.
So how many different types of MIs are there, and what is the difference between them? There are five different types of MIs, and they are categorized as follows:
As you have undoubtedly noticed, myocardial infarction codes now allow us to capture the “type” of MI that the patient experiences. This is very useful as more and more cardiologists had been specifically documenting type 2 MI and leaving us with no way to distinguish that particular type of MI from any other. 1st Qtr. 2017 Coding Clinic had instructed coders to use I21.4 for a type 2 MI which was the same code as a Non-ST elevation myocardial infarction. We were instructed to assign the type 2 to NSTEMI unless there was documentation that the MI was a STEMI. Now, however, we have a specific code, I21.A1, to assign when a patient has suffered a type 2 MI, regardless of whether they are specified as STEMI or NSTEMI.
So how many different types of MIs are there, and what is the difference between them? There are five different types of MIs, and they are categorized as follows:
Type 1- MI
resulting from plaque rupture or dissection
Type 2- MI
that occurs as a result of a supply/demand mismatch
Type 3- A
sudden cardiac death, without biomarker evidence of MI, but with signs of
ischemia
Type 4:
Type 4a- MI related to percutaneous
coronary intervention (PCI)
Type 4b- MI related to thrombosis in
a stent
Type 4c- MI related to a restenosis
(greater than 50%) post previously successful PCI
Type 5- MI
associated with a coronary artery bypass graft
The
corresponding ICD-10-CM codes for each type are:
Type 1-
I21.9, or code for MI of specific site, or code for STEMI or NSTEMI
Type 2-
I21.A1
Type 3-
I21.A9
Type 4 (a,
b, c) - I21.A9
Type 5-
I21.A9
In the
event there is an unspecified MI, then assign code I21.9.
A further
word regarding type 2 MIs; because this type of MI results from another
condition which is placing the supply/demand of myocardial oxygenation into an
imbalance, coders are directed to “Code also the underlying cause, if known and
applicable”. These conditions may include: heart failure,
shock, renal failure, anemia, or chronic obstructive pulmonary disease (COPD)
to name a few. The sequencing of the
codes would be dependent upon the circumstances of the admission.
There are
“Code first” and “Code also” notes associated with MI types 3-5 which must be
followed as well. The “Code first” note
requires code assignment for postprocedural MI if applicable, whereas the “Code
also” note is for capturing complications such as stent stenosis or thrombosis.
Now you are in the kNOW!!
About the Author
She recently served as the program director for Medical Coding and HIT at Eastern Gateway Community College. Dianna earned her bachelor's degree from the University of Cincinnati subsequently achieving her RHIA, CHPS, and CCS certifications. She is an AHIMA Approved ICD-10-CM/PCS Trainer and a a presenter at regional HIM meetings and the OHIMA Annual Meeting.