Introduction Heart disease, which includes coronary artery disease (CAD), is the leading cause of mortality in the U.S. To reduce the incidence of mortality, approximately 1.2 – 2 million cardiac stents are implanted each year worldwide. A cardiac stent or stents are deployed (inserted) into one or more affected cardiac arteries most commonly via a minimally invasive procedure, a percutaneous transluminal coronary balloon angioplasty (PTCA). This procedure may also be called an “angioplasty” for short, and may also be referred to in general, non-specific terms as “percutaneous coronary intervention (PCI).”
https://www.cdc.gov/nchs/fastats/leading-causes-of-death.htm
Coronary artery stenosis is a narrowing of a coronary artery due to build-up of fatty plaque. The narrowing causes a reduction of blood flow in the artery. Slow build-up of fatty plaque within the artery wall can cause the artery to narrow, reducing blood flow and potentially causing a myocardial infarction. As shown in the illustration below, the plaque is flattened via inflation of the balloon, and a stent is inserted to keep the artery open and blood flowing.
“In-stent restenosis” (ISR) is a condition in which narrowing has occurred in the previously placed coronary artery stent. The reasons for the ISR are multifactorial and include a progression of coronary artery disease, scar tissue or mechanical etiologies such as stent under-expansion.
Below is an illustration from the Boston Scientific website that shows ISR within a stent within a coronary artery. The plaque is brown/yellow. The stent is represented by the wavy lines.
https://www.bostonscientific.com/en-US/medical-specialties/interventional-cardiology/coronary-interventions/pci-product-portfolio/agent-ide-clinical-trial/understanding-isr-for-patients.html. This is an excellent resource that explains ISR and treatment options.
Background
A coronary stent was first implanted in a human in 1986, in Switzerland. This early stent device, known as the “Wallstent,” was comprised of wire-mesh (bare metal). Technical challenges with regard to the stent delivery system (deployment) limited its usefulness, and it was withdrawn from the market in 1991.
Around the same time period, in 1987 the first balloon-expandable, stainless steel stent device was developed by Palmaz-Schatzt® (Johnson & Johnson). This stent was the first Food and Drug Administration (FDA) approved stent for use in the U.S. and was widely used in the 1990s. Other stents were developed and subsequently came to use in the early 1990s, including the Flexstent® (Cook), Wiktor® (Medtronic), Micro® (Applied Vascular Engineering), Cordis® (Cordis) and Multi-link® (Advanced Cardiovascular Systems). (Some of our more experienced coder/blog readers will recognize these device names.)
Although effective in dilating and treating CAD, all of these older cardiac stents were bare-metal and found to have a substantial risk of in stent re-stenosis (ISR). To reduce the risk of ISR, drug-eluting stents (DES) were developed.
A drug-eluting stent (DES) is a stent that is coated with a polymer. The polymer contains a drug or drugs released (eluted) over time that promotes healing of the coronary artery and reduces the incidence of ISR. The drug(s) eluted from the polymer are depleted over time, approximately after 3 months, while the stent remains. A new type of stent, the SYNERGY BP Stent from Boston Scientific, was the first FDA-approved drug-eluting stent with abluminal bioabsorbable polymer coating available in the U.S. The polymer is absorbed about the same time as the drugs and according to Boston Scientific, “reduces the challenges associated with permanent polymer stents, including inflammation, neoatherosclerosis and late stent thrombosis.” https://www.bostonscientific.com/en-US/products/stents–coronary/bioabsorbable-polymer-stent/endotheliazation.html
Of note, there are several manufacturers of drug-eluting stents, including Boston Scientific as above, Medtronic and Abbot. Visit their respective websites to learn more.
Of note, there are recent advances to improve cardiac stents, such as the Medtronic Resolute Onyx DES. Read about this stent and see the illustration by visiting https://www.medtronic.com/us-en/healthcare-professionals/products/cardiovascular/stents/resolute-onyx-des.html. Scroll down to see different stent designs.
Here is a link to an article that explains types of stents, polymers and drugs (therapeutic compounds). https://www.ncbi.nlm.nih.gov/books/NBK537349/
Below are two cardiac angiogram images, showing the “before” and “after” results following balloon angioplasty and insertion of three cardiac stents. Although these images do not depict ISR, they illustrate the dramatic difference within the arteries after stent insertion.
Finally, here is, perhaps, a more entertaining link to an article that describes the origins and history of “stents.” Cardiac stents came much later than other types of and uses of stents; the term “stent” is attributed to an English dentist, Charles Thomas Stent (1807-1855). https://www.ahajournals.org/doi/full/10.1161/CIRCINTERVENTIONS.110.960872
Advice Sought from the American Hospital Association, “AHA Coding Clinic® for ICD-10-CM/PCS” from publication 4Q2021, Volume 8, Number 4, and effective with discharges October 1, 2021. You must have a subscription to “Coding Clinic” (CC) in order to read the entire questions and answers.
https://www.codingclinicadvisor.com/
Three scenarios and three questions were presented to “CC” for advice on reporting the correct diagnosis codes for “in-stent restenosis” (ISR) for each scenario.
Question #1 concerned a patient with known coronary artery disease (CAD), status post coronary intervention with stent insertion, now admitted for an acute non-ST elevated myocardial infarction (NSTEMI). Work-up revealed multiple vessel CAD and ISR. There was question as to whether the ISR was disease progression (CAD) or a complication of the stent. In this example, the provider documented and referenced a “culprit lesion” in the previously placed stent itself.
Term defined
Culprit lesion – what is or was determined to be the reason for the patient’s symptoms and in this case, the NSTEMI. The “lesions” refer to “plaque” that has ruptured or eroded causing stenosis and narrowing of a cardiac vessel or vessels. Culprit lesions may be newly diagnosed, disease progression OR a complication of a previously placed stent, i.e. ISR.
In this case, the provider clearly documented that the ISR caused the NSTEMI. Therefore, it is not considered a disease progression. “CC” advises that unless the provider documents that a culprit lesion is disease progression and not ISR, assign codes T82.855A, Stenosis of coronary artery stent, initial encounter, I21.A9. In this case, additional codes for the NSTEMI and CAD should also be assigned. Other myocardial infarction type, and I25.10, Atherosclerotic heart disease of native coronary artery without angina pectoris, for the NSTEMI caused by in-stent restenosis of the right coronary artery (culprit lesion) and CAD.
ICD-10-CM classifies stenosis or narrowing of a vessel involving a previously placed stent described as “within the stent” or “in-stent” restenosis, as a complication, unless specifically documented as due to disease progression.
Question #2 involved a patient admitted with an acute NSTEMI. During coronary intervention, the provider examined the patient’s coronary arteries and a previously placed stent, and documented severe two-vessel disease, including CAD and ISR. The NSTEMI was documented as due to the CAD and the ISR. Advice was sought as to whether two codes should be assigned – one for the ISR and one for the CAD – to show both reasons for the NSTEMI.
“CC” advised that yes, two codes should be assigned to fully describe the patient’s condition: T82.855A, Stenosis of coronary artery stent, initial encounter, I21.4, Non-ST elevation (NSTEMI) myocardial infarction, I21.A9 Other myocardial infarction type, and I25.10, Atherosclerotic heart disease of native coronary artery without angina pectoris, for the NSTEMI due to native artery CAD and in-stent restenosis.
Question #3 involved a patient with known CAD with three stents. The provider documented “in-stent restenosis” in all three stents but did not further specify or document the cause of the ISR, and so the coders questioned whether the provider should be queried.
Similar to Question Scenario #1, “CC” advised to assign code T82.855A, Stenosis of coronary artery stent, initial encounter, for the “in-stent” restenosis and I25.10, Atherosclerotic heart disease of native coronary artery without angina pectoris, for the
CAD. Again, stenosis or narrowing that is within the stent or “in-stent,” (ISR) is classified in ICD-10-CM as a complication unless specifically documented as due to disease progression.
Researching the diagnosis “In–Stent Restenosis” (ISR), (Coronary) for Coding
Begin with the Index, Main Term “Restenosis”
See the subterm “stent.”
Follow the subterms further; see “vascular, then “within the stent,” then “coronary.” T82.855
OR
Begin with the Index, Main Term “Restenosis”
See the subterm “in-stent,” then subterm “coronary vessel” T82.855
The coder is clearly directed to the Tabular entry T82.855. See the Index and Tabular entries referred to below.
Index
Tabular
Note the inclusion terms in T82.855 Stenosis of coronary artery stent:
In-stent stenosis (restenosis) of coronary artery stent
Restenosis of coronary artery stent
** Finally, add the 7th Character required to complete the code; in these three cases it is “A” for “initial encounter.
Summary
Heart disease, which includes coronary artery disease (CAD), is the leading cause of mortality in the U.S.
Coronary artery stenosis is a narrowing of a coronary artery due to build-up of fatty plaque. The narrowing causes a reduction of blood flow in the artery. To reduce the incidence of mortality from coronary artery disease, approximately 1.2 – 2 million cardiac stents are implanted each year world-wide.
Stent(s) are inserted to keep the coronary artery open with blood flowing.
In the past, “bare metal” stents were used. Today, “drug eluting” stents (DES) are most common. Stent designs and improvements are continuously researched.
A “culprit lesion” is what is or was determined to be the reason for the patient’s cardiac symptoms. The “lesions” refer to “plaque” that has ruptured or eroded causing stenosis and narrowing of a cardiac vessel or vessels.
“Culprit lesions” may be newly diagnosed, disease progression OR a complication of a previously placed stent, i.e. ISR.
“In-stent restenosis” (ISR) is a condition in which narrowing from plaque has occurred in the previously placed coronary artery stent.
ICD-10-CM classifies stenosis or narrowing of a vessel involving a previously placed stent described as “within the stent” or “in-stent” restenosis, as a complication, unless specifically documented as due to disease progression.
Reference to a “culprit lesion” should not be interpreted as meaning disease progression.
If the provider documents ”in-stent stenosis (restenosis) of coronary artery stent” or “restenosis of coronary artery stent,” the correct code to assign is T82.855. For an initial encounter, complete the code by adding the 7th character “A” for “initial encounter.”
There are several manufacturers of cardiac stents. We strongly encourage visiting their websites, some of which are listed below.
References and Resources
Centers for Disease Control and Prevention, National Center for Health Statistics. “Leading Causes of Death.” Source: Mortality in the United States 2019. https://www.cdc.gov/nchs/fastats/leading-causes-of-death.htm
Boston Scientific. Understanding In-stent Restenosis (ISR). https://www.bostonscientific.com/en-US/medical-specialties/interventional-cardiology/coronary-interventions/pci-product-portfolio/agent-ide-clinical-trial/understanding-isr-for-patients.html
Boston Scientific. SYNERGY Everolimus-Eluting Platinum Chromium Coronary Stent System. https://www.bostonscientific.com/en-US/products/stents–coronary/bioabsorbable-polymer-stent/endotheliazation.html
Medtronic. Resolute Onyx DES for Coronary Artery Disease. https://www.medtronic.com/us-en/healthcare-professionals/products/cardiovascular/stents/resolute-onyx-des.html
National Center for Biotechnology Information. U.S. National Library of Congress. PMD Publication 30726034. 2021. National Benjamin Senst; Amandeep Goyal; Judith Borger.”Drug Eluting Stent Compounds.” https://www.ncbi.nlm.nih.gov/books/NBK537349/
American Heart Association. Roguin, Ariel. “Stent: The Man and Word Behind the Coronary Metal Prosthesis.” Originally published 1 Apr 2011. https://www.ahajournals.org/doi/full/10.1161/CIRCINTERVENTIONS.110.960872
American Hospital Association. AHA Coding Clinic Advisor. https://www.codingclinicadvisor.com/
