Atrial fibrillation (afib) is the most common cardiac arrhythmia, and its coding and documentation implications are numerous. It is estimated that more than 4% of Americans over the age of 60 years are affected by afib. Common causes include heart failure, coronary artery disease, and hypertensive and valvular heart disease.
Afib represents disordered, chaotic atrial electrical activity with irregular atrioventricular (AV)-node conduction. The ventricular response is irregularly irregular, with no P-waves on an electrocardiogram (EKG). Afib often presents with a rapid ventricular response greater than 110 beats/min.
Atrial flutter is a pathophysiologic variant of afib characterized by a rapid, regular atrial rate, usually between 260 and 340 beats/min, typically with 2:1 AV-nodal block resulting in a regular ventricular rate of about 130 to 170 beats/min. A “saw-tooth” pattern of P-waves on EKG is characteristic. “Atrial flutter/fibrillation” is a term sometimes used to describe an EKG demonstrating alternating, variable patterns of both afib and atrial flutter.
There are four clinical types of afib: paroxysmal, persistent, long-standing persistent, and permanent. The ICD-10-CM codes and CC (comorbidity/complication) status for each type of afib are shown in the Table. For 2020, ICD-10-CM added new codes for chronic, permanent, persistent, and long-standing permanent afib, all of which are CCs.
The nonspecific term “chronic afib” indicates that afib of any type has lasted more than three months, and so could include permanent (the most common circumstance), persistent, or long-standing persistent afib.
Paroxysmal afib has an acute onset and terminates spontaneously or with intervention in seven days or less. When paroxysmal afib is successfully converted to sinus rhythm, long-term maintenance medication is usually required to prevent recurrences. Paroxysmal afib becomes persistent once it has lasted continuously for more than seven days despite efforts to correct it. As long as the conversion of persistent afib to sinus rhythm is intended and pursued (rhythm control), it is considered to be persistent.
In the unusual situation where conversion is pursued for more than 12 months, the condition then becomes long-term persistent afib. Once a decision is been made to terminate conversion attempts and implement rate-control therapy, the condition is considered permanent afib.
Paroxysmal and unspecified afib remain non-CCs in the latest version of ICD-10-CM. Atrial flutter is assigned code I48.92 (CC). When the diagnosis is atrial flutter/fibrillation, assign both codes based on the specific type of afib.
The specific type of afib should be documented and should never be left simply unspecified as “afib” because the correct CC status of each specified type must be captured. The coding of paroxysmal afib has important but clinically counterintuitive implications. When paroxysmal afib is being treated with medication to prevent recurrence, it should be coded even when afib is not present during an admission.
History of paroxysmal afib (code Z86.79) should not be used in this situation. In fact, if the condition was diagnosed more than three months prior, it may be documented simply as chronic afib (code I48.20) to capture the CC status. If it is documented as chronic paroxysmal, code I48.0 for paroxysmal afib (a non-CC) is assigned.
The specific type of afib should also be coded when a cardiac pacemaker or automatic implantable cardioverter-defibrillator is present. Afib successfully controlled by cardiac ablation alone (not requiring antiarrhythmic medications) should be documented as history of afib, code Z86.79 (non-CC). If, following cardiac ablation for afib, the patient still requires medication to prevent recurrences, the diagnosis should be afib (not history of).
In summary, the four clinical types of afib are paroxysmal, persistent, long-standing persistent, and permanent. The specific type of afib should be documented rather than left as unspecified afib (code I48.91, a non-CC). The nonspecific term “chronic afib” indicates that afib of any type has lasted more than three months and will be assigned code I48.20 (a CC) when the specific type of afib is not documented. History of afib (code Z86.79) should not be used except when paroxysmal afib has been converted to sinus rhythm and requires no ongoing treatment to prevent recurrence or when afib has been controlled with ablation therapy alone.