Cardiology Coding Alert

Use this fifth digit when a patient with an MI is moved to a different location

If you always tack on an unspecified diagnosis code for a myocardial infarction (MI) when you don't have enough information, then you may not be doing your job to the best of your ability. Part of being a good coder is investigating cases when a cardiologist doesn't fully document when the MI happened and what portion of the heart wall the MI damaged.

Follow these four steps, and you'll be choosing the most specific diagnosis code every time.

Step 1: Highlight 410 Series for Acute MI

A patient has an MI (commonly known as a heart attack). Your cardiologist sees the patient in the hospital, the office or another setting during the eight weeks immediately following the MI. You should code the diagnosis using the 410 series (Acute myocardial infarction), with required fourth and fifth digits, says Donna Baird, RHIT, ACS-CA, coding compliance coordinator at the Heart Center in Topeka, Kan. 

"When coding an MI, it's always nice to have information on the exact location and episode of care, but we don't always get it," says Joanna Anderson, CPC, billing manager and coder at Peninsula Cardiology Associates in Salisbury, Md.

Don't fall for "unspecified": You may look to 410.90 (Acute myocardial infarction; unspecified site and episode of care) if you lack necessary documentation, but don't fall into that trap. 

A cardiologist should be able to determine -- through a combination of diagnostic testing -- an MI's specific location, experts point out. You should talk with your physician regarding the importance of both the MI's location and episode.

What you need to know: You need to figure out where the MI occurred to pick the correct fourth digit, ranging from 0 (Of anterolateral wall) to 9 (Unspecified site). You also have to decide on a fifth digit. Your options are 0 (Episode of care unspecified), 1 (Initial episode of care) or 2 (Subsequent episode of care).

Step 2: Find Out Where for 'MI'

If the cardiologist documents only "MI," you should plan on doing some investigating. 

Strategy: One tactic is to check for an emergency department (ED) note. You may be able to look at the EKG findings (such as elevation in the inferior and lateral leads) and question either the attending ED physician or a cardiologist to see if the ED note findings are consistent with, for example, an inferolateral MI.

You may also want to check for a cardiac catheterization, coronary angioplasty, echocardiography or even a nuclear perfusion scan report in the chart, but make sure you confirm the MI location with your cardiologist or the attending physician.

If the patient presents with symptoms and positive test results and your cardiologist only documents "MI" (without stating the site or episode of care), however, you can opt to use 410.90, Anderson says.

Step 3: Know When for 'History of MI'

A patient has no cardiac symptoms three months after her MI and is returning for a checkup. Your cardiologist writes "history of MI" without noting when the MI occurred.

What to do: "Always verify with records to make sure this is truly a history of MI and not an acute one," Baird recommends. You should use 412 (Old myocardial infarction) for a healed MI or past MI diagnosed using an EKG or other means but the patient presents with no current symptoms.

Important: When you check with your cardiologist or his documentation, you should look up when the MI occurred. For example, if the MI occurred seven weeks ago, you should use the 410 series. If the MI is much older and the patient has no related symptoms, the MI may fit the criteria for 412.

Note: You can also use 412 as a second diagnosis when your cardiologist sees a patient who endured an MI in the past -- whether three months or three years ago. "I use 412 as a supporting diagnosis when there is an old diagnosed MI without patient symptoms," Anderson says.

Step 4: Reflect Episode of Care With Fifth Digit

Remember, you must also use a fifth digit with 410: "1" is immediate: Choose 1 (Initial episode of care) for the period of care immediately following an MI until the patient is discharged, no matter where the cardiologist provides the care. 

Example 1: "If the patient presents with symptoms, positive test results, and no previous history of an infarction but the cardiologist doesn't document the site, then I use 410.91," Anderson says.

Example 2: If the patient is admitted to a hospital with an MI, then moved to another location for treatment, you should still use 1 as the fifth digit, regardless of the amount of time spent at each facility. Why: Because the cardiologist did not discharge the patient home, you should treat this all as the same episode of care.

When care is subsequent, choose "2": Use 2 (Subsequent episode of care) when the patient is "admitted for further observation, evaluation or treatment for a myocardial infarction that has received initial treatment but is still less than eight weeks old," ICD-9 says.

Example 1: A patient who went home after having an MI six weeks ago comes back to the hospital for a cardiac catheterization. The eight-week window is still open (meaning you should consider this an "acute" MI and look to the 410 code series), but the initial episode of care ended with the patient's discharge. So you should use 2 as the fifth digit.

Example 2: A patient presents to the cardiologist'soffice six weeks after discharge for a previous MI. The cardiologist performs an EKG, which shows only the previously diagnosed anterior wall infarction. "You should use 410.12 (Acute myocardial infarction; of other anterior wall, subsequent episode of care)," Anderson says.

Note: Once the infarction is more than eight weeks old, you should use 414.8, Anderson adds. This diagnosis code's descriptor specifically states "any condition classifiable to 410 specified as chronic or presenting with symptoms after eight weeks from date of infarction."

Key: If you're confused about the difference between 412 (Old myocardial infarction) and 414.8 (Other specified forms of chronic ischemic heart disease), experts recommend you refer to the notes listed under the codes' descriptions. You'll see that 412 is for the post-acute patient who is presenting without symptoms, whereas 414.8 is for the post-acute patient with symptoms.

Not enough info? Fall back on "0": Use 0 (Episode of care unspecified) when you do not have enough information to assign 1 or 2. You should use this digit rarely because you should always code to the greatest specificity possible, and you should be able to locate information on when the MI occurred in most cases. "I have never used the fifth digit '0,'" Anderson says.

Use what you've learned: Putting all five digits together, you would use 410.31 (Acute myocardial infarction; of inferoposterior wall; initial episode of care) for an encounter with a patient who had an MI of the inferoposterior wall three weeks ago and has not been discharged from care. But if the same patient is discharged and then returns for observation or a procedure, you would code the visit as 410.32.