CPT code 33521: CABG grafting, four venous grafts2026 Medicare rate & RVUs in Michigan
Reports the venous-graft portion of combined coronary bypass surgery when four venous grafts are placed alongside one or more arterial grafts.
CMS doesn’t publish an office rate for 33521 in Michigan.
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 33521 covers
This add-on code represents the venous-graft portion of coronary artery bypass grafting that also uses an arterial conduit. A cardiac surgeon may use saphenous vein for the venous grafts and an internal thoracic artery or another arterial conduit for the arterial grafting. The service is performed during the same open-heart operation, typically in a hospital operating room.
Select the code by the number of venous grafts in the combined procedure: this level represents four. Report it only with the appropriate primary arterial CABG code, selected according to the arterial graft count, such as 33533–33536. The operative report should identify the arterial and venous conduits and support the number of grafts placed. Under the CMS rule, this add-on is billed only with a primary procedure and is paid 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 33521 pays more and less in Michigan
| Payment locality | Office | Facility |
|---|---|---|
| Detroit, MI | Unavailable | $659.76 |
| Rest of Michigan | Unavailable | $599.14 |
How the 33521 rate is calculated
Each of 33521’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 · 33521
RVUs × geographic indexes × conversion factor
Work12.28
12.28 RVUs× 1.000 GPCI
Practice expense2.45
2.45 RVUs× 1.000 GPCI
Malpractice3.03
3.03 RVUs× 1.000 GPCI
Adjusted RVUs
17.7600
Conversion factor
$33.4009
Medicare rate
$593.20
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 33521
The CMS indicators that decide how 33521 is paid alongside other services.
CMS payment indicators · 33521
CABG grafting, four venous grafts
| 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) | 2 | Paid. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
What modifiers do to the payment
Modifier 80 · payment effect
With and without the modifier
33521 without 80 · national facility
$593.20
CABG grafting, four venous grafts
33521-80 · Assistant: 16%
$94.91
A physician assistant at surgery is paid 16% of the surgeon’s fee schedule amount.
33521 compared with similar codes
Compare codes · National
5 codes, side by side
How to choose
- 33513Coronary bypassFour venous grafts
- 33513 represents four venous grafts in vein-only CABG. Use 33521 when arterial grafting is also part of the operation.
- 33519CABG graftsThree venous grafts
- Both codes represent combined arterial and venous CABG; 33519 is for three venous grafts, while 33521 is for four.
- 33522Coronary bypassFive venous grafts
- 33522 is the combined-grafting level for five venous grafts. Choose 33521 when four are documented.
- 33536CABGFour or more arterial grafts
- 33536 identifies the arterial-graft portion when four or more arterial grafts are used; 33521 identifies the four-venous-graft portion of combined CABG.
33521 billing questions
When should 33521 be selected instead of 33513?
Use 33521 for four venous grafts in a CABG that also includes arterial grafting. Code 33513 is the four-vein level for vein-only CABG.
Which primary code is reported with 33521?
Report it with the primary arterial CABG code that reflects the number of arterial grafts, from 33533–33536. The operative report should support both graft counts.
Does 33521 represent four distal targets?
Select the level based on the number of venous grafts, not simply the number of coronary targets described. Review the operative report for the conduits and grafts placed.
Can 33521 be billed by itself?
No. CMS identifies it as an add-on code, so it must be billed with a qualifying primary procedure.
What documentation supports 33521?
The operative report should identify the venous and arterial conduits and document four venous grafts, along with the arterial grafting represented by the primary code.
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
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