Condition guide
Atrial Fibrillation HCC Coding Guide
Atrial Fibrillation (e.g. I48.0) maps to HCC 238 (Specified Heart Arrhythmias) under CMS-HCC V28. Its source-labeled community non-dual aged reference coefficient is 0.299. This is not a member total; full contribution depends on hierarchy, cleanup, interactions, member context, and model year. Z79.01, long term (current) use of anticoagulants, is non-HCC under V28.
Quick Facts
HCC Categories
HCC 238, Specified Heart Arrhythmias
RAF Weight Range
0.299
Community, non-dual, aged (V28)
Model
CMS-HCC V28 (PY2026, 100% phase-in)
9 ICD-10 codes map to payment HCCs
How coders write it
Chart notes, problem lists, and queries rarely spell out Atrial Fibrillation. The shorthand you will actually see:
Whatever the note calls it, the payment question is the same: how the ICD-10-CM code resolves to a payment HCC.
What HCC category does Atrial Fibrillation map to under V28?
Atrial fibrillation (AFib) is the most common cardiac arrhythmia, affecting roughly 6 million Americans, and is a payment HCC under CMS-HCC V28. The I48 codes map to HCC 238 (Specified Heart Arrhythmias), which carries a community non-dual aged RAF of 0.299. Coding specificity still matters: document the type as paroxysmal, persistent, longstanding persistent, chronic (permanent), or unspecified, plus whether the patient is on anticoagulation and the CHA2DS2-VASc stroke risk. Atrial fibrillation and atrial flutter have separate ICD-10 codes, but both land in HCC 238, so neither outranks the other for risk capture. Review how the arrhythmia is documented and addressed. MEAT can organize that review; apply the coding, encounter, program and payer requirements to determine reportability.
ICD-10 to HCC Mapping
| ICD-10 Code | Description | Billable | HCC Mapping |
|---|---|---|---|
| I48.0 | Paroxysmal atrial fibrillation | Yes | HCC 238 |
| I48.11 | Longstanding persistent atrial fibrillation | Yes | HCC 238 |
| I48.19 | Other persistent atrial fibrillation | Yes | HCC 238 |
| I48.20 | Chronic atrial fibrillation, unspecified | Yes | HCC 238 |
| I48.21 | Permanent atrial fibrillation | Yes | HCC 238 |
| I48.91 | Unspecified atrial fibrillation | Yes | HCC 238 |
| I48.3 | Typical atrial flutter | Yes | HCC 238 |
| I48.4 | Atypical atrial flutter | Yes | HCC 238 |
| I48.92 | Unspecified atrial flutter | Yes | HCC 238 |
| Z79.01 | Long term (current) use of anticoagulants | Yes | No HCC (not risk-adjusting under V28) |
Displayed numbers are source-labeled community non-dual aged reference coefficients from CMS-HCC V28, not member totals.
Verify Atrial Fibrillation against the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coder workflow notes
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Documentation Tips
Document the specific type of atrial fibrillation: paroxysmal, persistent, longstanding persistent, or permanent.
Record current anticoagulation therapy and specify the agent (warfarin, apixaban, rivaroxaban, etc.) as part of the treatment review.
Include the CHA2DS2-VASc score to support medical decision-making and treatment rationale.
Document rate vs. rhythm control strategy and current heart rate during the encounter.
Note any prior cardioversion attempts, ablation procedures, or device implantation (pacemaker/ICD) history.
If the patient has both atrial fibrillation and atrial flutter, code both separately (I48.0-I48.21 and I48.3-I48.4).
MEAT documentation examples for Atrial Fibrillation
These examples organize documentation review using the MEAT review mnemonic for Atrial Fibrillation. Follow the applicable coding, encounter, program and payer requirements; these examples do not establish reportability on their own.
MMonitor
“Heart rate 78 and irregularly irregular today; ECG confirms atrial fibrillation, no pauses.”
“Patient reports two self-limited palpitation episodes since last visit, each under a day.”
EEvaluate
“Echocardiogram reviewed: left atrium enlarged, EF 55 percent.”
“CHA2DS2-VASc 4 and HAS-BLED 2 recalculated at this visit; renal function stable for dose.”
AAssess
“Paroxysmal atrial fibrillation, rate controlled, on anticoagulation.”
“Permanent atrial fibrillation with adequate rate control; no bleeding on apixaban.”
TTreat
“Continue apixaban 5 mg twice daily and metoprolol succinate 50 mg daily.”
“Referred to electrophysiology to discuss ablation for symptomatic paroxysmal episodes.”
Common Coding Mistakes
Coding I48.91 (unspecified atrial fibrillation) when the provider has documented the specific type (paroxysmal, persistent, permanent).
Confusing 'chronic' atrial fibrillation with 'permanent', chronic AFib (I48.20) is a less specific code than permanent AFib (I48.21).
Not capturing atrial fibrillation when it appears in the problem list but is not addressed at the encounter, AFib must be monitored, evaluated, assessed, or treated.
Missing the long-term anticoagulation code (Z79.01) as a supporting code, though it is not an HCC itself.
V24 to V28 Changes
Under CMS-HCC V28, the I48 atrial fibrillation and flutter codes map to HCC 238 (Specified Heart Arrhythmias), with a community non-dual aged RAF of 0.299. The transition from the prior V24 model renumbered and recalibrated the arrhythmia category rather than expanding what AFib captures, so the dollar value attached to a documented, actively managed AFib shifted with the new coefficients. AFib remains a payment HCC in V28. Keep in mind that many conditions split across several HCCs, where a base code and its manifestation codes land in different categories. AFib is simpler: every I48 code in this family rolls up to the single HCC 238, so your focus stays on type specificity, MEAT support, and clean documentation rather than chasing multiple categories.
| Aspect | V24 (through PY2025) | V28 (PY2026) |
|---|---|---|
| Paroxysmal, persistent, or permanent atrial fibrillation (I48.0, I48.11, I48.19, I48.21) | HCC 96, Specified Heart Arrhythmias, RAF 0.268 | HCC 238, Specified Heart Arrhythmias, RAF 0.299 |
| Unspecified atrial fibrillation (I48.91) and chronic, unspecified (I48.20) | HCC 96, RAF 0.268 | HCC 238, RAF 0.299; the type refines the code, not the category |
| Atrial flutter (I48.3, I48.4, I48.92) | HCC 96, RAF 0.268 | HCC 238, RAF 0.299 |
| Long-term anticoagulant use (Z79.01) | No payment HCC | No payment HCC; it supports the treatment element, not a category |
| What actually changed | One category, number 96 | Same label, renumbered to 238, community coefficient up from 0.268 to 0.299 |
These values are community, non-dual, aged code-level coefficient references for each model's payment year, not full member scores. For CMS-HCC V28 PY2026 member scoring with complete context, open the RAF Calculator. No score is shown unless every required source and calculation check passes.
Atrial Fibrillation coding FAQs
What HCC category does Atrial Fibrillation map to under V28?
Under CMS-HCC V28, Atrial Fibrillation maps to HCC 238 (Specified Heart Arrhythmias). The source-labeled community non-dual aged reference coefficient range is 0.299. These coefficients are not member totals; full contribution depends on hierarchy, cleanup, interactions, member context, and model year.
What ICD-10 codes map to HCC for Atrial Fibrillation?
Key ICD-10-CM codes for Atrial Fibrillation with CMS-HCC V28 mappings include: I48.0 (Paroxysmal atrial fibrillation); I48.11 (Longstanding persistent atrial fibrillation); I48.19 (Other persistent atrial fibrillation); I48.20 (Chronic atrial fibrillation, unspecified). HCC Buddy shows the available mapping and documentation guidance, with source-labeled code-level coefficient references on public pages. The RAF Calculator supports CMS-HCC V28 PY2026 with complete member context and shows no score unless every required check passes.
How did V28 change the HCC mapping for Atrial Fibrillation?
Under CMS-HCC V28, the I48 atrial fibrillation and flutter codes map to HCC 238 (Specified Heart Arrhythmias), with a community non-dual aged RAF of 0.299. The transition from the prior V24 model renumbered and recalibrated the arrhythmia category rather than expanding what AFib captures, so the dollar value attached to a documented, actively managed AFib shifted with the new coefficients. AFib remains a payment HCC in V28. Keep in mind that many conditions split across several HCCs, where a base code and its manifestation codes land in different categories. AFib is simpler: every I48 code in this family rolls up to the single HCC 238, so your focus stays on type specificity, MEAT support, and clean documentation rather than chasing multiple categories.
What documentation is required to code Atrial Fibrillation for HCC?
Document the specific type of atrial fibrillation: paroxysmal, persistent, longstanding persistent, or permanent. Record current anticoagulation therapy and specify the agent (warfarin, apixaban, rivaroxaban, etc.) as part of the treatment review. For Atrial Fibrillation, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. HCC Buddy's condition guides provide documentation checklists for Atrial Fibrillation.
What does atrial fibrillation (HCC) mean?
It means the documented atrial fibrillation code maps to a CMS-HCC category, HCC 238 (Specified Heart Arrhythmias) under V28. Every I48 atrial fibrillation and atrial flutter code lands in the same category, so the HCC label on a chart tells you the condition risk-adjusts; it does not tell you which type was documented.
What is paroxysmal atrial fibrillation (CMS HCC) and what is its ICD-10 code?
Paroxysmal atrial fibrillation is I48.0, an episode pattern that starts and stops on its own, usually within seven days. It maps to CMS-HCC V28 HCC 238 with a community non-dual aged reference coefficient of 0.299, the same category as persistent (I48.11, I48.19), permanent (I48.21), and unspecified (I48.91) atrial fibrillation.
What does atrial fibrillation with RVR (HCC) mean?
RVR is rapid ventricular response, a rate description, not a separate ICD-10-CM code. Report the atrial fibrillation type the provider documents (I48.0, I48.11, I48.19, I48.20, I48.21, or I48.91); the RVR belongs in the note as monitoring and treatment evidence. The category is HCC 238 either way.
What is the difference between atrial fibrillation and paroxysmal atrial fibrillation?
Paroxysmal is one of the documented patterns: episodes that terminate within seven days (I48.0). Persistent lasts longer than seven days (I48.19, or I48.11 when longstanding beyond a year), and permanent means rhythm control has been abandoned (I48.21). Unspecified atrial fibrillation (I48.91) is the code when the provider does not state the pattern. All of them risk-adjust to HCC 238; the pattern matters for code accuracy and for what the note should show.
Related Conditions
Related references
CMS-HCC V28 model
How V28 categories, source-labeled coefficient references, and hierarchy work for PY2026.
ICD-10 to HCC mapping
How an ICD-10-CM code resolves to a payment HCC under V28.
MEAT criteria
The documentation standard every coded condition must satisfy.
Every I48 code (Atrial fibrillation and flutter)
9 billable codes, 9 with a CMS-HCC V28 category, in one table.
Sources
Displayed numbers are source-labeled community non-dual aged reference coefficients from CMS-HCC V28, not member totals.
Verified current to CMS-HCC V28, payment year 2026 — last reviewed September 5, 2026.
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