Atrial Fibrillation and Secondary Hypercoagulable State

In recent years, there has been considerable discussion and debate about whether healthcare providers should be queried to diagnose secondary hypercoagulable state in patients with atrial fibrillation who are receiving anticoagulant treatment.

As outlined in our CDI Pocket Guide®, without clinical indicators of a hypercoagulable state, it is not appropriate to query for this diagnosis in patients with atrial fibrillation who are being treated with anticoagulants, from both a clinical and coding standpoint.

From a clinical perspective, we refer primarily to the “2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines.”

These guidelines do not mention hypercoagulopathy as being associated with any type of atrial fibrillation. “Hypercoagulable state” is only recognized as one of the risk factors for thromboembolism in patients with atrial fibrillation who also have a pre-existing hypercoagulable condition, such as active malignancy or genetic thrombophilia.

Additionally, it is noted that patients with atrial fibrillation associated with liver disease may develop a coagulation deficiency due to the disruption of coagulation factors, which constitutes a hypo-coagulopathy rather than hyper-coagulopathy.

Atrial fibrillation results from disordered, chaotic atrial electrical activity leading to irregular ventricular contraction, with the atria failing to contract. Strokes related to atrial fibrillation are primarily caused by clots forming in the left atrium due to stagnant blood flow since the atria are not contracting. This phenomenon is not attributable to a systemic coagulation disorder.

The clinical practice guidelines indicate that patients with atrial fibrillation may exhibit “prothrombotic changes,” which are localized to the left atrial wall and not due to circulating clotting factors (the cause remains unknown). A hypercoagulable state is a systemic disorder of blood clotting factors, which can be either inherited (genetic) or acquired and is classified under code category D68, “Other coagulation defects,” intended for systemic coagulation disorders.

It is important to note that atrial fibrillation does not cause abnormalities or defects in coagulation. If a systemic hypercoagulable state were associated with atrial fibrillation, all patients would require treatment with anticoagulants; however, many patients do not receive such treatment. Patients are prescribed anticoagulant therapy based on risk factors (e.g., congestive heart failure, age >75, diabetes mellitus, history of stroke, transient ischemic attack, or thromboembolism), rather than for a systemic hypercoagulable state. The treatment addresses the potential risk of localized thrombosis in the left atrium.

There are two primary scenarios in which a patient with atrial fibrillation on anticoagulants might have a hypercoagulable state:

• The patient has a pre-existing hypercoagulable state, such as an inherited thrombophilia or acquired hypercoagulopathy due to severe malignancy.

• The anticoagulant therapy has induced hypercoagulopathy, which is exceedingly rare, and if it occurs, the anticoagulants would be discontinued—this would serve as a clinical indicator justifying a query.

The impetus for querying in these instances originated from the 2021 Coding Clinic, which suggested, “Patients with atrial fibrillation on chronic anticoagulant therapy may have an increased incidence of acquired hypercoagulable state,” although this occurrence is very rare.

From a coding standpoint, assigning an additional diagnosis of “secondary hypercoagulable state” (code D68.69) in a patient with only atrial fibrillation on anticoagulants (absent any other evidence of hypercoagulopathy) would not meet the criteria for a secondary diagnosis, as it would not necessitate “clinical evaluation, treatment, diagnostic procedures, extended length of stay, increased nursing care, or monitoring.” It should be noted that anticoagulants are administered for the treatment of atrial fibrillation.

As stated in our CDI Pocket Guide®, additional clinical evidence is required to support a query or diagnosis of systemic hypercoagulable state, such as thrombosis while on anticoagulant therapy, a diagnostic test identifying a prothrombotic disorder, a hematology consultation, severe malignancy, or the discontinuation of anticoagulant therapy. Clinical indicators such as these would substantiate a query for a possible hypercoagulable state and likely fulfill the criteria for a secondary diagnosis.