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CPT code 33866: Aortic graft, hemiarch extension2026 Medicare rate & RVUs

Reports graft reconstruction of the aortic hemiarch added to an eligible ascending aortic replacement during open repair of complex aortic disease.

CMS RVU26DEffective Oct 1, 2026109 payment localities2.2K Medicare services in 2024

Medicare pays $836.69 for 33866 nationally in a facility.

Medicare rate · 33866

Aortic graft, hemiarch extension

Office or facility?

Work RVUs
17.31
Total RVUs
25.05
Global days
ZZZ

National rate · 2026

$836.69

Facility setting, before claim adjustments.

See every locality for 33866 →Billed by an NP, PA or therapist? →

Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.

Your location

Medicare pays by the payment locality where the service is performed.

On this page 10 sections
  1. Medicare rate
  2. What 33866 covers
  3. By payment locality
  4. Rate map
  5. How it’s calculated
  6. Payment rules
  7. Similar codes
  8. Related codes
  9. Billing questions
  10. Sources

What 33866 covers

This add-on describes reconstruction of the proximal aortic arch’s hemiarch segment as part of an open aortic operation. The cardiac surgeon replaces the diseased portion with graft material, often while treating aneurysmal or other complex disease that also requires ascending aortic replacement. These procedures are typically performed in a hospital operating room with cardiopulmonary bypass; the operative report should identify the hemiarch work and the extent of aortic replacement performed.

Report 33866 with an eligible primary ascending aortic replacement, such as 33858, 33859, 33863, or 33864; it is not a stand-alone service. Documentation should distinguish hemiarch reconstruction from replacement limited to the ascending aorta and describe the grafted segment. CMS treats this as an add-on code billed with the primary procedure, with payment within that procedure’s global period.

This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.

Where 33866 pays more and less

The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.

109 of 109 payment localities

33866 office and facility rates by payment locality
Payment localityOfficeFacility
AlabamaUnavailable$760.31
AlaskaUnavailable$1,069.27
ArizonaUnavailable$812.56
ArkansasUnavailable$751.18
Atlanta, GAUnavailable$868.95
Austin, TXUnavailable$828.31
Bakersfield, CAUnavailable$803.04
Baltimore area, MDUnavailable$888.21
Beaumont, TXUnavailable$816.14
Brazoria, TXUnavailable$808.90

33866 rates by state

Office rate range in each state. Select a state to see its payment localities.

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Local rates. Clear comparisons.

Hover or focus a tile to see its rate range. Select it to open the state’s fee schedule.

View every state and territory as a table
33866 office rate range by state
State / territoryOffice rate rangeLocalities
AKNo published base rate1
ALNo published base rate1
ARNo published base rate1
AZNo published base rate1
CANo published base rate29
CONo published base rate1
CTNo published base rate1
DCNo published base rate1
DENo published base rate1
FLNo published base rate3
GANo published base rate2
GUNo published base rate1
HINo published base rate1
IANo published base rate1
IDNo published base rate1
ILNo published base rate4
INNo published base rate1
KSNo published base rate1
KYNo published base rate1
LANo published base rate2
MANo published base rate2
MDNo published base rate3
MENo published base rate2
MINo published base rate2
MNNo published base rate1
MONo published base rate3
MSNo published base rate1
MTNo published base rate1
NCNo published base rate1
NDNo published base rate1
NENo published base rate1
NHNo published base rate1
NJNo published base rate2
NMNo published base rate1
NVNo published base rate1
NYNo published base rate5
OHNo published base rate1
OKNo published base rate1
ORNo published base rate2
PANo published base rate2
PRNo published base rate1
RINo published base rate1
SCNo published base rate1
SDNo published base rate1
TNNo published base rate1
TXNo published base rate8
UTNo published base rate1
VANo published base rate2
VINo published base rate1
VTNo published base rate1
WANo published base rate2
WINo published base rate1
WVNo published base rate1
WYNo published base rate1

How the 33866 rate is calculated

Each of 33866’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.

How the rate is built · 33866

RVUs × geographic indexes × conversion factor

Office or facility?

Work17.31

17.31 RVUs× 1.000 GPCI

Practice expense3.47

3.47 RVUs× 1.000 GPCI

Malpractice4.27

4.27 RVUs× 1.000 GPCI

Adjusted RVUs

25.0500

Conversion factor

$33.4009

Medicare rate

$836.69

Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.

Payment rules and modifiers for 33866

The CMS indicators that decide how 33866 is paid alongside other services.

CMS payment indicators · 33866

Aortic graft, hemiarch extension

RuleCMS valueWhat it means
Global periodZZZAdd-on code: falls within the primary procedure’s global period.
Multiple procedures0No multiple-procedure reduction.
Bilateral (modifier 50)0The 150% bilateral adjustment doesn’t apply.
Assistant at surgery (80/81/82/AS)0Not paid without supporting documentation.
Co-surgeons (62)0Not permitted.
Team surgery (66)1Permitted with supporting documentation.
Professional/technical0Physician service: no professional/technical split.

33866 compared with similar codes

Compare codes · National

4 codes, side by side

Office or facility?

  • 33866

    Aortic graft, hemiarch extension17.31 wRVU

    Not priced

  • 33858

    Aortic graft, ascending aorta, dissection61.82 wRVU

    Not priced

  • 33863

    Aortic graft, valve conduit, coronary reconstruction57.32 wRVU

    Not priced

  • 33871

    Aortic arch graft, transverse arch, hypothermic arrest59.36 wRVU

    Not priced

How to choose

33858Aortic graftAscending aorta, dissection
33858 reports an ascending aortic replacement primary operation; 33866 captures additional hemiarch graft reconstruction when performed with an eligible primary procedure.
33863Aortic graftValve conduit, coronary reconstruction
33863 identifies an ascending aortic and root replacement using a composite graft. Add 33866 when the operative work also includes hemiarch reconstruction.
33871Aortic arch graftTransverse arch, hypothermic arrest
33871 describes replacement of the transverse arch. Code 33866 is for a hemiarch graft added to an eligible ascending aortic replacement.

Codes related to 33866

Related codes aren’t interchangeable: bill the code that matches the service performed.

Codes related to 33866
CodeHow it relatesNational office range
Add-on codes
33858Aortic graft, ascending aorta, dissectionEligible ascending aortic replacement primary procedure for hemiarch graft reconstruction.No office rate
33859Aortic graft, non-dissection diseaseEligible ascending aortic replacement primary procedure for hemiarch graft reconstruction.No office rate
33863Aortic graft, valve conduit, coronary reconstructionAscending aortic and root replacement that may be paired with the hemiarch add-on.No office rate
33864Aortic graft, with root replacement and CABGAscending aortic and root replacement that may be paired with the hemiarch add-on.No office rate
Used instead
33871Aortic arch graft, transverse arch, hypothermic arrestUsed for transverse arch replacement when the documented reconstruction extends beyond a hemiarch.No office rate

33866 billing questions

Which primary codes can be paired with 33866?

It is reported as an add-on with eligible ascending aortic replacement procedures, including 33858, 33859, 33863, and 33864. The operative report must support that hemiarch reconstruction was performed.

Can 33866 be reported by itself?

No. CMS identifies it as an add-on code, so it must be billed with a primary procedure and is paid within that procedure’s global period.

How is hemiarch reconstruction distinguished from an ascending aortic graft?

The documentation should show that the graft reconstruction extended into the hemiarch, rather than being limited to the ascending aorta. The primary code identifies the associated ascending aortic operation.

When is a broader arch replacement code more appropriate?

When the operative work replaces the transverse aortic arch rather than a hemiarch segment, compare the documented extent with code 33871. The code selection should follow the actual arch reconstruction performed.

What should the operative report document?

It should describe the diseased aortic segments treated, the hemiarch graft reconstruction, and the associated primary ascending aortic replacement. This supports reporting the add-on with the operation that required it.

Where these rates come from

FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.

CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027

Show the CMS file lines behind this rate
RVUs for 33866PPRRVU2026_Oct_nonQPP.csv, line 4,094 (RVU26D)

Open CMS sourceHow we calculate rates

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