ICD-10 G45.9
Billable / Specific CCTransient cerebral ischemic attack, unspecified
About ICD-10-CM G45.9
ICD-10-CM code G45.9 represents Transient cerebral ischemic attack, unspecified. This is a billable/specific code in the Nervous System chapter (block G45). The 2026 edition of ICD-10-CM G45.9 became effective on October 1, 2025.
Coding Tips for G45.9
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
G45.9 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC 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 G45.9. Per CMS ICD-10-CM Tabular 2026.
- Spasm of cerebral artery
- TIA
- Transient cerebral ischemia NOS
Inpatient DRG Impact, CC
codes Transient cerebral ischemic attack, unspecified. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for G45.9
Local Coverage Determinations (LCDs) from CMS MACs that list G45.9 as a covered diagnosis.
Showing top 10 of 747 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing G45.9.
2 Aetna
3 Cigna
5 Medicare
CPT Codes Commonly Billed with G45.9
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
- 93243 CMS LCD: Billing and Coding: Ambulatory Electrocardiograph (AECG) Monitoring CMS LCD
- 93242 CMS LCD: Billing and Coding: Ambulatory Electrocardiograph (AECG) Monitoring CMS LCD
- 93245 CMS LCD: Billing and Coding: Ambulatory Electrocardiograph (AECG) Monitoring CMS LCD
- 93270 CMS LCD: Billing and Coding: Ambulatory Electrocardiograph (AECG) Monitoring CMS LCD
- 0940T CMS LCD: Billing and Coding: Ambulatory Electrocardiograph (AECG) Monitoring CMS LCD
- 93298 CMS LCD: Billing and Coding: Ambulatory Electrocardiograph (AECG) Monitoring CMS LCD
- 93247 CMS LCD: Billing and Coding: Ambulatory Electrocardiograph (AECG) Monitoring CMS LCD
- 93226 CMS LCD: Billing and Coding: Ambulatory Electrocardiograph (AECG) Monitoring CMS LCD
- 93271 CMS LCD: Billing and Coding: Ambulatory Electrocardiograph (AECG) Monitoring CMS LCD
Convert G45.9 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 |
|---|---|---|
| G45.9 | 4359 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To G45.9
Other codes in section G40-G47 (Episodic and paroxysmal disorders).
ICD-10 G45.9, Billing FAQ
Is ICD-10 code G45.9 billable? +
Yes, G45.9 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 G45.9? +
ICD-10 G45.9 includes: Spasm of cerebral artery; TIA; Transient cerebral ischemia NOS.
Is G45.9 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with G45.9? +
Procedures frequently paired with G45.9 include: 93880, 93243, 93242, 93245, 93270.
What ICD-9 codes does G45.9 map to? +
Per CMS GEMs, G45.9 maps to ICD-9 codes: 4359. 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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