November 5, 2012

Acute Coronary Syndrome Coding Challenges
By Judy Sturgeon, CCS, CCDS
For The Record
Vol. 24 No. 20 P. 6

When a physician documents acute coronary syndrome (ACS) in the chart of a hospital inpatient, it is not challenging to assign a code in the ICD-9-CM system. The index and tabular directions are clear: The code for acute coronary syndrome is 411.1—exactly the same as for a diagnosis of unstable angina. Simple enough, right?

Of course there’s a catch because very little in hospital coding is that straightforward. While assigning a code for the term is easy, determining whether the physician is really diagnosing the patient with unstable angina is not. ACS serves as an excellent example of how it may take years for codes to catch up to current medical terminology. In today’s cardiology lingo, ACS is a term that includes not only unstable angina but potentially one of two types of myocardial infarction (MI) as well: ST elevation MI (STEMI) and non-STEMI (or NSTEMI).

The former is named for the ST elevations found by performing an electrocardiogram (EKG) on admission to the hospital. Conversely, the NSTEMI presents without ST elevations on the EKG. Unstable angina, which is defined by several characteristics, often involves previously diagnosed angina that has become significantly more severe and is occurring at rest. Often the cause of all three, demand ischemia is defined as a circumstance in which the cardiac need for blood exceeds the supply immediately available to the heart muscle. Causes can include coronary plaque, anemia, arterial spasm, thrombus, embolism, and hypertension.

Laboratory results showing elevated levels of troponin and/or cardiac enzymes often indicate an MI. However, unstable angina also can produce an abnormal EKG or slightly elevated troponin levels. What’s more, false-positive results also can occur in the presence of renal failure, heart failure, rhabdomyolysis, and even trauma.

Significance of Making the Distinction
While coders are relieved of the obligation of diagnosing a patient, instructions from the Council on ICD-9-CM are clear: It is always the coder’s responsibility to request clarification from the physician when documentation is ambiguous, unclear, or contradictory.

Why does it matter? Whether the final coding indicates unstable angina or an MI affects more than the hospital payment from diagnosis-related group payers such as Medicare and Medicaid. Public healthcare organizations use this information to compare severity of illness and risk of mortality among hospitals. It is also required quality reporting for core measures data, which can significantly affect hospital reimbursement for an entire year. As a result, it is critical that a physician’s intended meaning for a diagnosis of ACS is coded and reported correctly.

Physicians may alternately use the terms chest pain, ACS, atypical chest pain, troponin leaks, and STEMI or NSTEMI for the same patient on the same admission. When do you query and when do you code?

Real-Life Examples
Patient A presents to the emergency department (ED) with chest pain, elevated serial troponins, elevated cardiac enzymes, and an abnormal EKG with ST elevations. The ED physician documents STEMI and admits the patient. Following a coronary catheterization, significant coronary artery disease is found, and two stents are placed in coronary arteries. The patient stays in-house for another day then is discharged for cardiac rehabilitation with a final diagnosis that lists both STEMI and coronary artery disease. There is no coding challenge here: Code the STEMI to the site, if known, and code the coronary artery disease along with the coronary arteriogram and the stent placements.

Patient B presents to the telemetry unit on Friday afternoon after a direct admission from his clinic. The chief complaint is new severe chest pain after mowing his lawn. His medical history includes atrial fibrillation, controlled by medication, and hypertension. His blood pressure is elevated at 160/90. Troponin is slightly elevated; cardiac enzymes are elevated; and his EKG is abnormal. As a result, the admitting physician documents NSTEMI.

The patient is sent for a coronary arteriogram that shows no significant coronary artery disease. Because his chest pain has resolved, he is soon discharged and schedules an appointment with a cardiologist in two days. Hospital policy states that the short stay will not have a formal discharge summary dictated. The discharge progress note by a resident physician documents “acute coronary syndrome, normal coronary arteries.”

Does this mean the patient did not have an NSTEMI? Perhaps. But it also might mean that while the patient did have an NSTEMI, it was not caused by coronary artery disease. He certainly has other factors that could cause the symptoms: recent strain of mowing, hypertension, and atrial fibrillation. This case needs clarification of what is meant by the discharging physician’s ACS diagnosis so that the coder can assign the correct diagnosis.

Patient C presents to the ED with shortness of breath, diaphoresis, and blood pressure of 200/110. His serial troponins are elevated, and he is diagnosed with an NSTEMI. His EKG is complicated by mechanical problems with the leads, but the patient’s history includes an MI five years ago. He does not respond to initial medical treatment, so he is rushed for a coronary arteriogram. While it does show some coronary artery disease, none is significant enough to require intervention. The patient’s symptoms resolve; his medications are refilled and adjusted; and the discharging physician documents “ACS, resolved. Troponin leak due to HTN.” The patient is subsequently referred to his regular cardiologist.

Should the acute MI be coded because it’s the most specific diagnosis in the chart? Or should it be coded that the patient merely had unstable angina because at discharge there was no mention of the MI? It might mean that the physician was in a hurry to attend to the next patient and it was faster to write “ACS, resolved” than it was to note, “This patient didn’t have a STEMI, but while his clinical presentation is a mild NSTEMI caused by his greatly elevated hypertension, his symptoms have resolved with aggressive treatment. He doesn’t require any immediate percutaneous intervention so he can be discharged for follow up as an outpatient.”

Walking a Tightrope
Coders must always balance speed with accuracy. If the hospital has sufficient staffing and a top-notch clinical documentation improvement program, the coders’ need to query may be significantly reduced. But any time there is a diagnosis of ACS and the physician’s intended meaning is unclear, coders are professionally obliged to query the physician for further clarification. There is simply too much at stake to do anything less.

— Judy Sturgeon, CCS, CCDS, is the clinical coding/reimbursement compliance manager at Harris County Hospital District in Houston and a contributing editor at For The Record. While her initial education was in medical technology, she has been in hospital coding and compliance for 21 years.