Official guidance on ICD-10-CM coding raises questions regarding how to document cardiac care.

The first step in choosing the proper ICD-10-CM code is reading the medical documentation to identify the diagnosis the provider has documented and confirmed. If there is no confirmed diagnosis, look for the sign or symptom that brought the patient in for the encounter.

Well, at least that is what we have been taught, and have had hammered into our thinking – not only with ICD-9, but with the launching of ICD-10 in 2015, and its platform of “coding to the highest specificity.” That is why I am at a loss when it comes to the 2018 instructions for coding hypertensive heart disease in the ICD-10-CM Official Guidelines for Reporting for FY 2018.

I have had many coders ask me, are we supposed to assume a disease has a causal relationship when it is not documented as such by the physician?

What coders are referring to are the stated ICD-10-CM guidelines on this topic, and how they have coders scratching their heads, having to go against everything they have been taught about code selection.

First, let’s look at what hypertensive heart disease is.

Hypertensive heart disease refers to heart conditions caused by high blood pressure.

The heart working under increased pressure may cause some different heart disorders. Hypertensive heart disease includes heart failure, thickening of the heart muscle, coronary artery disease, and other conditions.

Hypertensive heart disease can cause serious health problems. It’s the leading cause of death from high blood pressure. In general, the heart problems associated with high blood pressure relate to the heart’s arteries and muscles. The types of hypertensive heart disease include the following:


Narrowing of the Arteries

Coronary arteries transport blood to the heart muscle. When high blood pressure causes the blood vessels to become narrow, blood flow to the heart can slow or stop. This condition is known as coronary artery disease (CAD), also called coronary heart disease, and now with ICD-10, athersclerotic heart disease of a specified artery.

CAD makes it difficult for the heart to function and supply the rest of the organs with blood. It can put a patient at risk for a heart attack from a blood clot that gets stuck in one of the narrowed arteries and cuts off blood flow to the heart.


Thickening and Enlargement of the Heart

High blood pressure makes it difficult for the heart to pump blood. Like other muscles in the body, regular hard work causes the heart muscles to thicken and grow. This alters the way the heart functions. These changes usually happen in the main pumping chamber of the heart, the left ventricle. The condition is known as left ventricular hypertrophy (LVH).

CAD can cause LVH, and vice versa. When you have CAD, your heart must work harder. If LVH enlarges your heart, it can compress the coronary arteries.



Both CAD and LVH can lead to:

  • Heart failure: your heart is unable to pump enough blood to the rest of your body
  • Arrhythmia: your heart beats abnormally
  • Ischemic heart disease: your heart doesn’t get enough oxygen
  • Heart attack: blood flow to the heart is interrupted and the heart muscle dies from lack of oxygen
  • Sudden cardiac arrest: your heart suddenly stops working, you stop breathing, and you lose consciousness
  • Stroke and sudden death

So with this much information available to describe the properties of a combination disease, i.e. heart disease with hypertension, or hypertensive heart disease, why do the ICD-10-CM Official Guidelines state in its instructions to coders the following:

Chapter 9: Diseases of the Circulatory System (I00-I99)

  1. Hypertension

This classification presumes a causal relationship between hypertension and heart involvement and between hypertension and kidney involvement, as the two conditions are linked by the term “with” in the Alphabetical Index. These conditions should be coded as related even in the absence of provider documentation explicitly linking them, unless the documentation clearly states the conditions are unrelated.

For hypertension conditions not specifically linked by the relational terms, such as “with” or “associated with” or “due to” in the classification, provider documentation must link the conditions in order for them to be related.

Where my issue lies here is in the fact that the instructions are telling a coder that if there is both hypertension and CAD documented in a report or patient encounter, it is “okay” (or should I say, acceptable, and even instructed) to assume a causal relationship without specific documentation from the physician linking these diagnoses.

I agree that certain types of hypertension “may” lead to heart disease and even kidney disease, but unless a physician states a relationship, is it appropriate to put that into the hands of a coder who may not have a clinical background? The Guidelines tell us yes, like it or not.

In saying that, I do believe that this could have an impact on risk adjustment and Hierarchical Condition Category (HCC) coding. This is the payment model mandated by the Centers for Medicare & Medicaid Services (CMS) in 1997. Implemented in 2003, this model identifies individuals with serious or chronic illness and assigns a risk factor score to the person based upon a combination of the individual’s health conditions and demographic details. The individual’s health conditions are identified via ICD-10 diagnoses that are submitted by providers on incoming claims. There are more than 9,000 ICD-10 codes that map to 79 HCC codes in the risk adjustment model. 

CMS requires documentation in the medical record by a qualified healthcare provider to support the submitted diagnosis. Documentation must support the presence of the condition and indicate the provider’s assessment and/or plan for management of the condition. This must occur at least once each calendar year in order for CMS to recognize that the individual continues to have the condition.    

Trying to comply with this model without certain documented causal factors linking two diagnoses, and being instructed by ICD-10-CM to link them, even in the absence of provider documentation, will make HCCs and reporting that much more difficult in the future.



Terry Fletcher, BS, CPC, CCC, CEMC, CCS, CCS-P, CMC, CMSCS, CMCS, ACS-CA, SCP-CA, QMGC, QMCRC, is a healthcare coding consultant, educator, and auditor with more than 30 years of experience. Terry is a past member of the national advisory board for AAPC, past chair of the AAPCCA, and an AAPC national and regional conference educator. Terry is the author of several coding and reimbursement publications, as well as a practice auditor for multiple specialty practices around the country. Her coding and reimbursement specialties include cardiology, peripheral cardiology, gastroenterology, E&M auditing, orthopedics, general surgery, neurology, interventional radiology, and telehealth/telemedicine. Terry is a member of the ICD10monitor editorial board and a popular panelist on Talk Ten Tuesdays.

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