Updated October 2026 for 2027. CPT codes reflect the current code set, and ICD-10-CM and ICD-10-PCS codes reflect the FY2027 code sets effective October 1, 2026.
Quick answer: Medical coding for CABG uses CPT 33510 to 33516 when only vein grafts are used, 33533 to 33536 when arterial grafts are used, and add on codes +33517 to +33523 for vein grafts performed together with arterial grafts. For example, 2 arterial grafts plus 2 vein grafts is 33534 and +33518. Inpatient facility claims use ICD-10-PCS root operation Bypass (021), and the usual diagnosis is I25.10, atherosclerotic heart disease of native coronary artery without angina.
New to medical coding? See how our CPC Training gets you certified.
What is CABG and why is it hard to code?
Coronary artery bypass grafting (CABG) is a common but complex surgery used to treat coronary artery disease. It reroutes blood around blocked coronary arteries using grafts, which can be:
- Venous: usually the greater saphenous vein from the leg
- Arterial: commonly the internal mammary (thoracic) artery or the radial artery
Coding complexity increases with the number of grafts, the type of grafts, whether the procedure is on pump or off pump, and any concurrent procedures such as a valve repair. Learn more in our guide to STEMI and NSTEMI coding.
What are the CPT codes for CABG?
| Graft Type | CPT Codes | How to Count |
|---|---|---|
| Venous grafts only | 33510 to 33516 | 33510 single, 33511 two, 33512 three, 33513 four, 33514 five, 33516 six or more vein grafts |
| Arterial grafts | 33533 to 33536 | 33533 single, 33534 two, 33535 three, 33536 four or more arterial grafts |
| Combined arterial and venous | +33517 to +33523 | Add on to 33533 to 33536: +33517 one, +33518 two, +33519 three, +33521 four, +33522 five, +33523 six or more vein grafts |
| Reoperation | +33530 | Add on for a repeat CABG or valve procedure more than one month after the original operation |
The key rule: Never report a venous only code (33510 to 33516) together with an arterial code (33533 to 33536). When both graft types are used, report the arterial code for the number of arterial grafts and add the combined venous add on code for the number of vein grafts.
Are graft harvests reported separately?
Harvest of the saphenous vein and the internal mammary artery is included in the CABG codes. Some harvests are reported separately with add on codes:
- +33508: Endoscopic harvest of a vein for bypass graft
- +35500: Harvest of an upper extremity vein, one segment
- +35600: Harvest of an upper extremity artery (such as the radial artery), one segment
How is CABG coded in ICD-10-PCS for inpatient claims?
Inpatient facility claims use ICD-10-PCS. Each CABG code is built from seven characters:
- Section: 0 (Medical and Surgical)
- Body system: 2 (Heart and Great Vessels)
- Root operation: 1 (Bypass)
- Body part: the number of coronary arteries bypassed: 0 one artery, 1 two arteries, 2 three arteries, 3 four or more arteries
- Approach: 0 open or 4 percutaneous endoscopic
- Device: 8 autologous arterial tissue, 9 autologous venous tissue, J synthetic substitute, K nonautologous tissue substitute, or Z no device (for an in situ internal mammary artery)
- Qualifier: where the bypass comes from, such as W aorta, 8 right internal mammary or 9 left internal mammary
Examples:
- 02100Z9: Bypass of one coronary artery from the left internal mammary, open approach (the classic in situ LIMA to LAD graft)
- 021009W: Bypass of one coronary artery from the aorta with autologous venous tissue, open approach
- 021109W: Bypass of two coronary arteries from the aorta with autologous venous tissue, open approach
Code a separate PCS code for each distinct combination of device and qualifier, and count the coronary arteries bypassed, not the number of grafts.
What should coders check in the operative report?
- Number of coronary arteries bypassed
- Type of each graft (arterial or venous) and whether it is in situ or free
- Origin and destination of each graft
- Harvest technique (open or endoscopic) and harvest site
- Pump technique (on pump or off pump)
- Any concurrent procedures
Which modifiers apply to CABG?
- 22: Increased procedural services, only when documentation supports substantially greater work
- 62: Two surgeons acting as co surgeons, each performing distinct parts of the procedure
- 80 or 82: Assistant surgeon, when the payer allows assistant surgery for the code
See our CPT and HCPCS modifiers guide for more detail. Add on codes such as +33517 are reported only with their primary procedure code and never stand alone.
Which ICD-10-CM codes support CABG?
- I25.10: Atherosclerotic heart disease of native coronary artery without angina pectoris
- I25.11-: Atherosclerotic heart disease of native coronary artery with angina pectoris (code the type of angina)
- I25.810: Atherosclerosis of coronary artery bypass graft(s) without angina pectoris
- Z95.1: Presence of aortocoronary bypass graft, for later encounters after the surgery
Always check NCCI edits to confirm that your code combinations are allowed.
What are the most common CABG coding errors?
| Error | How to Avoid It |
|---|---|
| Reporting venous only and arterial codes together | Use 33533 to 33536 with the +33517 to +33523 add on codes |
| Counting the wrong number of grafts | Carefully review the operative report for each graft |
| Reporting saphenous vein or internal mammary harvest separately | These harvests are included; only report +33508, +35500 or +35600 when documented |
| In PCS, counting grafts instead of arteries | The body part character is the number of coronary arteries bypassed |
| Incorrect use of modifiers | Apply only when documentation supports them |
How do you code a 4 vessel CABG with arterial and vein grafts?
Scenario: A patient with coronary artery disease without angina undergoes an open, on pump CABG with 4 grafts: a left internal mammary artery in situ to the LAD, a free radial artery graft from the aorta to one artery (harvested through a separate open incision), and 2 saphenous vein grafts from the aorta to two other arteries.
- CPT: 33534 (2 arterial grafts), +33518 (2 venous grafts), +35600 (radial artery harvest)
- ICD-10-CM: I25.10
- ICD-10-PCS: 02100Z9 (LIMA to one artery), 021008W (radial artery from aorta to one artery), 021109W (vein grafts from aorta to two arteries)
Frequently asked questions
What is the CPT code for a CABG with 3 vein grafts?
CPT 33512 reports a CABG using 3 venous grafts only.
How do you code a CABG with both arterial and vein grafts?
Report the arterial code (33533 to 33536) for the number of arterial grafts plus the add on code (+33517 to +33523) for the number of vein grafts.
Is the internal mammary artery harvest reported separately?
No. Harvest of the internal mammary artery and the saphenous vein is included. A radial artery harvest is reported with +35600, and an endoscopic vein harvest with +33508.
What does the fourth character mean in a PCS CABG code?
The body part character identifies the number of coronary arteries bypassed: 0 for one, 1 for two, 2 for three and 3 for four or more.
What ICD-10-CM code is used after a patient has had a CABG?
Z95.1, presence of aortocoronary bypass graft, reports the status after surgery. Atherosclerosis of the graft itself is coded from I25.81-.
Where can coders find more CABG guidance?
- CPT Assistant articles
- AHA Coding Clinic for ICD-10-CM and ICD-10-PCS
- NCCI Policy Manual
- AAPC: CABG Bypass Problematic Coding Scenarios
- Medical Coding Arteries and Veins
- Coronary Artery Disease (CAD) Medical Coding
- Medical Coding Reference Library
Accurate CABG coding requires close attention to clinical documentation and the procedural components. By following official coding guidelines, coders can ensure correct billing, reduce denials and support clinical and financial outcomes.
Ready to code like this for a living?
Coding Clarified’s AAPC licensed CPC program takes you from beginner to certified, with an internship and a job board for graduates.
You may qualify for WIOA funding in 30+ states. Check your eligibility.