CPT code 33866: Aortic graft, hemiarch extension2026 Medicare rate & RVUs in Missouri
Reports graft reconstruction of the aortic hemiarch added to an eligible ascending aortic replacement during open repair of complex aortic disease.
CMS doesn’t publish an office rate for 33866 in Missouri.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
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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 in Missouri
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
| Payment locality | Office | Facility |
|---|---|---|
| Metropolitan Kansas City, MO | Unavailable | $826.34 |
| Metropolitan St. Louis, MO | Unavailable | $831.41 |
| Rest of Missouri | Unavailable | $816.99 |
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
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
| Rule | CMS value | What it means |
|---|---|---|
| Global period | ZZZ | Add-on code: falls within the primary procedure’s global period. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 0 | Not paid without supporting documentation. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 1 | Permitted with supporting documentation. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
33866 compared with similar codes
Compare codes · National
4 codes, side by side
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.
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
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