What No Map Can Tell You about ICD-10: Coronary Angioplasty and MS-DRGs, Part 2

Last time I exhausted my blog space and myself and probably a few readers describing in principle how the differences in the language of ICD-9 and ICD-10 impact the MS-DRG assignment of angioplasty procedures. In this blog, it’s time to get off the soapbox and play in the sandbox. Here is a sample set of procedure scenarios we can mess around with to show how they will be coded and reimbursed in the past, the future, and in the fun house mirror view you sometimes get from mapping.

First, a quick review of the differences in angioplasty coding between ICD-9 and ICD-10, and the MS-DRGs assigned for coronary artery procedures.

In ICD-9, the axis of classification is the number of distinct coronary vessels treated.

In ICD-10, the axis of classification is the total number of sites treated, regardless of which coronary artery it is.

MS-DRGs assigns separate DRGs for angioplasties using these distinctions: 246 and 248 for 4+ distinct vessels treated or 4+ stents placed, 247 for drug-eluting stents, 249 for non-drug-eluting stent, and 250-251 for angioplasties without stents and less than four distinct vessels treated. Remember, a lower number MS-DRG means it is higher in the hierarchy.

Scenario 1: Four sites, two vessels, two drug-eluting stents

  • Four sites on two coronary vessels are angioplastied, and drug-eluting stents are placed at two of the sites.
    • Coded directly in ICD-10 takes two codes, because the sites without stents are coded separately from the sites with stents.
    • Coded directly in ICD-9 takes four codes because all the components of the procedure are coded separately: number of vessels, number of stents, the fact that a stent was drug-eluting, and the angioplasty itself.
    • Mapped from ICD-9 to ICD-10, even a good mapper will only produce the single ICD-10 code containing the two sites with the stents because it must equate the ICD-9 language of vessels with the ICD-10 language of sites.
    • ICD-10 and ICD-9 MS-DRG groupers assign the record to the same MS-DRG, 247 Percutaneous cardiovascular procedure with drug-eluting stent. The mapped ICD-10 record gets the same result, since the ICD-10 grouper can’t take account of the ICD-10 code with two sites but no stents.

Scenario 2: Four sites, four vessels, four drug-eluting stents

  • Four sites on four coronary vessels are angioplastied, and drug-eluting stents are placed at all four of the sites.
    • Coded directly in ICD-10 takes one code, because the number of sites and stents is the same, and all are drug-eluting.
    • Coded directly in ICD-9 still takes four codes for the same reason in scenario 1, this time with a code for four stents instead of two stents.
    • Mapped from ICD-9 to ICD-10, mapping software has to be sophisticated enough to look for all four ICD-9 codes and equate them with the correct ICD-10 procedure code. Country bumpkin mapping software will convert each ICD-9 code separately with its “closest ICD-10 equivalent.” It will produce an ICD-10 record also containing four codes which are a fun house mirror picture of the original procedure. Here is an example that maps each ICD-9 code to the last ICD-10 alternative (erroneously considered by some the “unspecified” choice) in the GEMs for each of the ICD-9 codes on the original record:

00.66 Percutaneous transluminal coronary angioplasty [PTCA]

mapped to 02C33ZZ Extirpation of Matter from Coronary Artery, Four or More Sites, Percutaneous Approach (#25 of 25 alternatives)

00.43 Procedure on four or more vessels

mapped to 02734ZZ Dilation of Coronary Artery, Four or More Sites, Percutaneous Endoscopic Approach (#64 of 64 alternatives)

00.48 Insertion of four or more vascular stents

mapped to 02734TZ Dilation of Coronary Artery, Four or More Sites with Radioactive Intraluminal Device, Percutaneous Endoscopic Approach (#18 of 18 alternatives)

36.07 Insertion of drug-eluting coronary artery stent(s)

mapped to 027344Z Dilation of Coronary Artery, Four or More Sites with Drug-eluting Intraluminal Device, Percutaneous Endoscopic Approach (#24 of 24 alternatives)

Not only is every one of these ICD-10 codes way off the mark for correct coding, the converted ICD-10 record claims that sixteen total sites were treated—a 400 percent exaggeration of the total work performed.

  • The ICD-10 grouper touts up the total number of stents and the record is assigned to MS-DRG 246 Percutaneous cardiovascular procedure with drug-eluting stent with MCC or 4+ vessels/stents. The ICD-9 grouper looks at both the number of vessels and the number of stents placed, but the result is still the same as the ICD-10 grouper. The mapped ICD-10 record, amazingly, gets the same result.

Scenario 3: Four sites, four vessels, two drug-eluting stents

  • Four sites on four distinct coronary vessels are treated, but drug-eluting stents are placed at only two of the sites.
    • Coded directly in ICD-10 takes two codes—one for the two sites with stents and one for the two sites without stents—and is identical to the coding in scenario one, because ICD-10 classifies the total number of sites treated and not the number of distinct coronary arteries treated. The fact that the angioplasties occurred on four separate vessels does not change the coding.
    • Coded directly in ICD-9 takes four codes—one specifies four vessels treated, two stents placed, the fact that a stent was drug-eluting, and the angioplasty itself.
    • Mapped from ICD-9 to ICD-10, even the smartest mapping software that looks for input ICD-9 clusters of codes that translate to a single ICD-10 code will be confounded by the number of possibilities here.  Four ICD-9 codes need to translate to two ICD-10 codes. There is no way to correctly guess how many total sites were treated (one per vessel? Two? A mix?) or whether one or both stents were drug-eluting.
    • The ICD-10 grouper touts up the total number of stents treated but ignores the number of sites since it cannot translate ICD-9 requirement to specify the number of vessels. The record is assigned to 247 Percutaneous cardiovascular procedure with drug-eluting stent. The ICD-9 MS-DRG grouper uses the “four or more vessels” ICD-9 code to assign the record to 246 Percutaneous cardiovascular procedure with drug-eluting stent with MCC or 4+ vessels/stents.

So, there you have it. I feel like I have just administered the maximum recommended dose of tough love. Are you feeling it?

2 responses to “What No Map Can Tell You about ICD-10: Coronary Angioplasty and MS-DRGs, Part 2

  1. New to ICD-10=PCS. Percutaneous transluminal angioplasty of two sites in the same vessel, one involving a drug-eluting stent and one without. Would you have 2 codes – one with the stent placed and one without?

  2. Thanks for your comment. That’s correct, in the case you describe the device values are different, so two procedure codes are used to describe the episode. Below are the relevant sentences from the official PCS guidelines on that subject, for reference.
    B3.6b
    Coronary arteries are classified by number of distinct sites treated, rather than number of coronary arteries or anatomic name of a coronary artery (e.g., left anterior descending)…
    B3.6c
    If multiple coronary artery sites are bypassed, a separate procedure is coded for each coronary artery site that uses a different device and/or qualifier.

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