Coding Notes
The Circulatory System and
ICD-10-CM/PCS
By Ann Barta, MSA, RHIA
MANY CODING PROFESSIONALS will need to learn new ter- minology and brush up on their anatomy and physiology (A&P) knowledge to prepare for the ICD-10-CM/PCS transition. Al- though it is still too early for intense training on the new code sets, now is the time for coding professionals to gain knowledge on how ICD-10-CM/PCS differs from ICD-9-CM, in addition to refreshing their A&P knowledge. This article focuses on some of the terminology and classifica- tion changes in circulatory system conditions and discusses the A&P knowledge required to code circulatory procedures. ICD-10-CM
Chapter 9 in ICD-10-CM classifies diseases and disorders of the
circulatory system and includes categories I00–I99. The chapter’s organization is comparable to chapter 7’s organization in
ICD-9-CM with one notable change in the order of conditions
under the section for ischemic heart diseases (I20–I25). In ICD-
9-CM the first condition classified under ischemic heart disease
is acute myocardial infarction, whereas angina pectoris is the
first condition classified in ICD-10-CM.
Hypertension
The nature of hypertension (benign, malignant, or unspecified)
is no longer an axis for classifying hypertension in ICD-10-CM.
Instead, hypertension is classified only by type, primary or secondary. There is only one code (I10) for essential or primary
hypertension. Coding professionals would assign I10 if the physician documented arterial, benign, essential, malignant, primary, or systemic hypertension.
Myocardial Infarction
The definition and terminology for an acute myocardial infarction has also been updated in ICD-10-CM. The time frame for
an acute myocardial infarction has changed from eight weeks
or less in ICD-9-CM to four weeks or less in ICD-10-CM. In addition, ST elevation and non-ST elevation are in the ICD-10-CM
code titles. In ICD-9-CM these are just inclusion terms and are
not included in the code titles. The table to the right provides
a comparison of ICD-10-CM initial myocardial infarction code
titles with ICD-9-CM acute myocardial infarction code titles.
Certain codes from category I21 also classify the responsible
coronary artery. An example is I21.01, ST elevation (STEMI)
myocardial infarction involving left main coronary artery. In
addition, ICD-10-CM no longer classifies the episode of care
(initial versus subsequent).
ICD-10-CM also classifies subsequent acute myocardial infarctions to category I22, Subsequent ST elevation (STEMI) and
non-ST elevation (NSTEMI) myocardial infarction. A code from
category I22 is assigned when a patient who has suffered an initial acute myocardial infarction suffers a new acute myocardial
infarction within the four-week time frame of the initial acute
myocardial infarction.
Other Circulatory Conditions
Acute myocardial infarction is not the only circulatory condition with updated terminology. Additional examples of terminology differences between the two classification systems are
angina pectoris and acute coronary thrombosis not resulting in
myocardial infarction.
