ICD-10 I48.91
Billable / Specific HCC v28: 96Unspecified atrial fibrillation
About ICD-10-CM I48.91
ICD-10-CM code I48.91 represents Unspecified atrial fibrillation. This is a billable/specific code in the Circulatory System chapter (block I48). The 2026 edition of ICD-10-CM I48.91 became effective on October 1, 2025.
Coding Tips for I48.91
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
I48.91 is a CMS-HCC v28 risk-adjustment code (category 96). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Medicare LCD Coverage for I48.91
Local Coverage Determinations (LCDs) from CMS MACs that list I48.91 as a covered diagnosis.
Showing top 10 of 450 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing I48.91.
2 Aetna
5 Medicare
CPT Codes Commonly Billed with I48.91
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 99214 Established patient — moderate complexity: uncontrolled HTN, diabetes with complications, multiple chronic conditions, COPD, AFib, CKD, sleep apnea, chronic pain, depression Primary Care
- 99215 Established patient — high complexity: HF exacerbation, COPD exacerbation, cancer management, MS, advanced CKD, uncontrolled diabetes, recurrent syncope, respiratory failure, liver cirrhosis Primary Care
- 93000 EKG 12-lead — tachycardia, bradycardia, palpitations, HTN, CAD, AFib, arrhythmia, chest pain, syncope, cardiomyopathy, AV block, bundle branch block, SVT, VT, diabetes screening, abnormal EKG Cardiology
- 93010 EKG interpretation only — same dx as 93000 Cardiology
- 33208 CMS LCD: Billing and Coding: Single Chamber and Dual Chamber Permanent Cardiac Pacemakers � Coding and Billing CMS LCD
- 33206 CMS LCD: Billing and Coding: Single Chamber and Dual Chamber Permanent Cardiac Pacemakers � Coding and Billing CMS LCD
- 33207 CMS LCD: Billing and Coding: Single Chamber and Dual Chamber Permanent Cardiac Pacemakers � Coding and Billing CMS LCD
- 0573T CMS LCD: Billing and Coding: Implantable Automatic Defibrillators CMS LCD
- 0574T CMS LCD: Billing and Coding: Implantable Automatic Defibrillators CMS LCD
- 0614T CMS LCD: Billing and Coding: Implantable Automatic Defibrillators CMS LCD
Convert I48.91 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| I48.91 | 42731 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To I48.91
Other codes in section I30-I5A (Other forms of heart disease).
ICD-10 I48.91, Billing FAQ
Is ICD-10 code I48.91 billable? +
Yes, I48.91 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Does I48.91 affect Medicare Advantage HCC risk adjustment? +
Yes. I48.91 maps to CMS-HCC v28 category 96. Capture this diagnosis annually for accurate Medicare Advantage risk score.
What CPT codes are commonly billed with I48.91? +
Procedures frequently paired with I48.91 include: 99214, 99215, 93000, 93010, 33208.
What ICD-9 codes does I48.91 map to? +
Per CMS GEMs, I48.91 maps to ICD-9 codes: 42731. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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