Cardiology Coding Alert

Fifth Digit Coding Critical to Optimize Reimbursement for MIs

When coding for category 410 (Acute Myocardial Infarction) adding the fifth digit is vital to getting adequately reimbursed. Keeping track of the standard eight week treatment period is important, too. The fifth digit is a subclassification indicator and, for MIs, represents the episode of care. If you dont note it correctly, Medicare and third party payers will deny payment, stresses Susan Garrison, MPC, CPC, CPC-H, CPAR, president-elect of the American Academy of Professional Coders and senior manager at Hyatt, Imler, Ott, and Blount, a coding and billing consulting firm in Atlanta.

Coding to the highest possible degree of specificity helps expedite prompt payment because it decreases unprocessable denials, she says.

Understanding ICD-9 Classifications

Categories are three-digit codes that represent a group of conditions or a related condition. For example, category 410 is acute myocardial infarction, which includes an embolism, occlusion, rupture, or thrombosis of the coronary artery, as well as an infarction or rupture of the heart, myocardium, or ventricle.

Subcategories are four digit codes that provide more information such as the cause or site of the condition. For example, subcategories under 410 designate the location of the infarction:

410.0 - of the anterolateral wall

410.1 - of other anterior wall

410.2 - of inferolateral wall

410.3 - of inferoposterior wall

410.4 - of other inferior wall

410.5 - of other lateral wall

410.6 - True posterior wall infarction

410.7 - Subendocardial infarction

410.8 - of other specified sites

410.9 - Unspecified site

Subclassifications are fifth-digit codes that add even more information and specificity. For 410, the fifth digit is 0, an unspecified episode of care, 1, the initial episode of care, and 2, a subsequent episode of care. The term episode of care is related to documented duration of treatment, not locations of treatment, explains Sue Prophet, RRA, CCS, director of classification and coding for the American Health Information Management Association in Chicago.

Not all codes have fourth or fifth digits, But if there is one available, you should use it, she says.
Fifth Digits a Must for MIs

0 -- episode of care unspecified. This ones easy because youll rarely use it. Although the fifth digit of 0 is designed for instances when the medical record documentation doesnt have enough information to determine the episode of care, you should ask the physician to get the necessary information, Prophet says. By properly specifying the episode of care, you will significantly reduce denials for your MI claims.

By finding out how long ago the patient was diagnosed with an MI, you can then classify the episode more specifically with one of the following fifth digits:

1 -- initial episode of care. Use 1 for the first episode of a newly diagnosed MI. This designation is used throughout the entire eight-week treatment period regardless of the admission status [inpatient or outpatient], or the number of times the patient is transferred among acute-care facilities during the first episode, Prophet explains.

Paying attention to this eight-week period -- approximately the time it takes for heart tissue to form a firm scar and completely heal -- is the secret to correctly assigning the correct fifth digit.

Suppose the MI is less than eight weeks old AND the patient has not been discharged home or to a long-term care facility. Then any treatment rendered is considered part of the initial episode and assigned a fifth digit of 1. For example, the code for an initial episode of MI of the anterolateral wall would be 410.01.

But what if, during that initial period of hospitalization, the patient has a second MI in another part of the heart. Then youd assign a separate code for each site, Prophet instructs. For example, if the first MI was in the anterolateral wall, you would use 410.01. For the second MI in the anterior wall, you would use 410.11. During the initial episode, the fifth digit remains one regardless of the location of the infarction.

Remember, once the physician has provided the initial evaluation and/or treatment for MI and has discharged the patient home or to a long-term care facility, you dont use the fifth digit of 1 anymore -- unless the patient has a new heart attack.

2 -- the subsequent episode of care. However, if the second admission within the eight weeks is related to the previous one and not for a new MI, assign the fifth digit of 2 because it is considered a subsequent episode of care. For example, suppose a patient had had a previous MI and was discharged from the hospital and then readmitted four weeks later for a cardiovascular procedure. You would use the code 410.92 to indicate a subsequent episode.

The rule is that if the MI occurred less than eight weeks ago and the patient is readmitted for further observation, evaluation or treatment of that MI, it is a subsequent episode of care, Prophet says. After the eight-week period, if the patient has another episode, even at the same site, it should be coded as a new problem.