ICD-10 I63.9
Billable / Specific HCC v28: 100 MCCCerebral infarction, unspecified
About ICD-10-CM I63.9
ICD-10-CM code I63.9 represents Cerebral infarction, unspecified. This is a billable/specific code in the Circulatory System chapter (block I63). The 2026 edition of ICD-10-CM I63.9 became effective on October 1, 2025.
Coding Tips for I63.9
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
I63.9 is a CMS-HCC v28 risk-adjustment code (category 100). 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.
I63.9 is designated MCC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-MCC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag MCC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under I63.9. Per CMS ICD-10-CM Tabular 2026.
- Stroke NOS
Type 2 Excludes
Not included here, the excluded code is not part of I63.9, but a patient may have both conditions at the same time. Both codes may be coded together when applicable.
- transient cerebral ischemic attacks and related syndromes (G45.-)
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.
Inpatient DRG Impact, MCC
codes Cerebral infarction, unspecified. As a Major Complication/Comorbidity (MCC), this can shift the DRG assignment to a higher-weighted category, substantial reimbursement impact.
Medicare LCD Coverage for I63.9
Local Coverage Determinations (LCDs) from CMS MACs that list I63.9 as a covered diagnosis.
Showing top 10 of 418 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing I63.9.
1 Aetna
5 Cigna
5 Medicare
CPT Codes Commonly Billed with I63.9
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 93880 Duplex carotid — stroke, TIA, carotid stenosis, cerebral atherosclerosis, syncope, migraine, dizziness, headache, family hx vascular disease Cardiology
Convert I63.9 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 |
|---|---|---|
| I63.9 | 43491 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To I63.9
Other codes in section I60-I69 (Cerebrovascular diseases).
ICD-10 I63.9, Billing FAQ
Is ICD-10 code I63.9 billable? +
Yes, I63.9 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to I63.9? +
ICD-10 I63.9 includes: Stroke NOS.
What codes are Type 2 Excludes for I63.9? +
Type 2 Excludes (may be coded together when both conditions exist): transient cerebral ischemic attacks and related syndromes (G45.-)
Does I63.9 affect Medicare Advantage HCC risk adjustment? +
Yes. I63.9 maps to CMS-HCC v28 category 100. Capture this diagnosis annually for accurate Medicare Advantage risk score.
Is I63.9 a CC or MCC for inpatient DRG? +
Yes, this code is designated as MCC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with I63.9? +
Procedures frequently paired with I63.9 include: 93880.
What ICD-9 codes does I63.9 map to? +
Per CMS GEMs, I63.9 maps to ICD-9 codes: 43491. Useful for legacy data review and historical claim analysis.
Get the full PayerReady toolkit
Free access to CPT/ICD-10 lookup, denial appeals, fee comparator, and claim auditing with credentialing enrollment.
Start free →Run this code through our claim audit tool
Check NCCI bundling, MUE limits, and modifier logic before submission.
Try the auditor →Did this page help?
Quick signal so we know what to improve.
If you want a code reference page that doesn't exist yet, email coding@payerready.com.
Tell us what's missing or wrong: coding@payerready.com. We respond within 5 business days.
Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
Powered by 11K CPT · 98K ICD-10 · 860K MPFS rates · 4.5M NCCI edits · 9.5M NPIs. Our data methodology · About our coding team