CPT code 33405 – Open aortic valve replacement

Key takeaways

CPT code 33405 covers open aortic valve replacement on cardiopulmonary bypass (CPB) with a mechanical or bioprosthetic valve, not a homograft or stentless valve.

Cardiopulmonary bypass is bundled into 33405 and cannot be billed separately under any circumstance.

Homograft valves bill under 33406, stentless tissue valves under 33410, and transcatheter approaches under 33361-33366.

33405 carries a 90-day global period, and the hospital’s MS-DRG depends on whether cardiac catheterization was also performed.

Pabau’s claims management software connects to Claim.MD to submit, track, and reconcile cardiac surgery claims.

CPT code 33405: Official descriptor and quick-reference data

CPT code 33405 is the code for open aortic valve replacement on cardiopulmonary bypass using a mechanical or stented bioprosthetic valve. The American Medical Association defines it as “Replacement, aortic valve, open, with cardiopulmonary bypass; with prosthetic valve other than homograft or stentless valve.”

Every word in that descriptor carries billing weight. “Open” excludes transcatheter approaches. “Cardiopulmonary bypass” means CPB is required and bundled. “Prosthetic valve other than homograft or stentless” is the decisive differentiator from adjacent codes 33406 and 33410.

CPT 33405 at a glance

RVU values are updated annually in the CMS Physician Fee Schedule. Verify figures using the CMS PFS lookup tool or a current-year RVU calculator before using them in compensation benchmarking or claim submission.

Clinical context: What the operative report must document

Coders assign CPT code 33405 based on what the operative report confirms, not on the diagnosis alone. A 33405 claim without an operative note that names each required element is likely to be denied on documentation grounds.

The procedure follows a defined surgical sequence. Each step below corresponds to a documentation requirement the coder must locate before assigning the code.

1. Median sternotomy. The report must confirm an open chest approach. A percutaneous or minimally invasive approach routes to a different code family.
2. Cardiopulmonary bypass initiated. CPB must be documented as established. It is bundled into 33405 per CMS NCCI edits and cannot be billed separately.
3. Native valve excised. The report should state the diseased aortic valve was removed.
4. Prosthesis type identified. The valve implanted must be specifically described as mechanical or bioprosthetic (tissue). If the report says “homograft,” use 33406. If it says “stentless tissue valve,” use 33410. If the valve type is ambiguous, query the surgeon before assigning.
5. Prosthesis sized and implanted. Size and suture technique are not required for coding but support medical necessity if audited.
6. CPB discontinued; chest closed. Routine closure is included in the global package.

Preoperative documentation matters too. Prior authorization reviews and medical necessity audits typically ask for three records:

• An echocardiogram confirming severe aortic stenosis or regurgitation
• A heart team evaluation note
• The attending cardiologist’s referral

Bundled services and what can be billed separately

CPB is the most frequently unbundled service on 33405 claims. CMS NCCI edits prohibit separate billing of the bypass pump when it is performed as part of the valve replacement. The table below shows which related services are bundled and which can be billed on their own.

Concurrent CABG is the most common legitimate add-on for 33405. When valve replacement and bypass grafting happen in the same session, bill the CABG code (such as 33533 for an arterial graft) alongside 33405. Each code is reported separately, and modifier 51 may apply depending on payer rules.

NCCI edits are updated quarterly, so confirm current bundling rules before billing add-on procedures. Building that quarterly check into your medical billing compliance routine keeps unbundling errors off high-value claims.

Aortic valve code selection: 33405 vs 33406 vs 33410 vs TAVR codes

Choosing between the aortic valve codes hinges on two factors: the approach (open vs transcatheter) and the valve type implanted. The diagram below maps that decision, and the table after it adds the bypass requirement for each code.

The TAVR family (33361-33366) is coded by access approach (transfemoral, transapical, transaortic, etc.), not by valve type. A patient who had a transcatheter procedure but whose report is ambiguous about approach should not be coded as 33405. Query the operative note or contact the surgeon before assigning any open code to a minimally invasive procedure.

Valid modifiers for CPT code 33405

CPT code 33405 accepts several modifiers, each applying in a distinct surgical team or procedural scenario. Using the wrong modifier, or omitting one when it is required, is a direct path to claim denial.

Modifier 62 is the most scrutinized modifier on cardiac surgery claims. Both surgeons must bill 33405-62, and each must document their distinct contribution in a separate or co-signed operative note. A single note signed by one surgeon does not support the co-surgery modifier for the second.

CPT 33405 RVU values and Medicare reimbursement

CPT code 33405 carries one of the highest work RVU values in cardiac surgery, which reflects the complexity and time of open valve replacement. The professional fee component (what the surgeon bills) is separate from the facility fee the hospital receives through the DRG system.

Professional component (surgeon’s bill): The 2026 work RVU is 40.29. Combined with the practice expense and malpractice RVUs, it gives a total facility RVU of 63.65. To estimate the Medicare allowable, multiply that total by the CMS conversion factor and adjust for your locality’s geographic practice cost index (GPCI). The FastRVU lookup tool or the CMS PFS search pulls current-year figures by locality.

Hospital reimbursement via DRG: Most 33405 cases are billed as inpatient admissions, so the hospital is paid through the Medicare Inpatient Prospective Payment System. When cardiac catheterization is performed in the same admission, the case groups to MS-DRG 216, 217, or 218. Without catheterization, it groups to MS-DRG 219, 220, or 221.

Within each set of three, the DRG depends on whether a major complication or comorbidity (MCC) or a complication or comorbidity (CC) is documented. DRG payment is a bundled facility rate, separate from what the operating surgeon bills under the physician fee schedule.

Because 33405 is a facility-only code, the non-facility practice expense RVU does not apply. The procedure is always performed in an inpatient or outpatient hospital setting. Billing it with a non-facility place of service triggers an automatic denial.

ICD-10-CM diagnosis codes paired with CPT code 33405

Every 33405 claim requires a supporting ICD-10-CM diagnosis code that establishes medical necessity. The primary diagnosis must reflect the valvular pathology that drove the decision to operate. When the record points to a less common etiology, search the full ICD-10-CM code library for the most specific match.

Payers expect the documented diagnosis to match what the echocardiogram confirmed. A claim listing I35.0 with no echo in the record showing severe stenosis will likely be denied for medical necessity. Check insurance eligibility and coverage criteria for the diagnosis before submitting, particularly for Medicare Advantage plans.

Prior authorization, documentation and global period for CPT code 33405

Three distinct compliance layers govern every 33405 claim: prior authorization (before the procedure), documentation (during and after), and global period rules (for 90 days post-surgery).

Prior authorization: Traditional Medicare fee-for-service does not require prior authorization for inpatient procedures. Medicare Advantage plans and most commercial payers do.

Standard requirements include an echocardiogram confirming severe aortic stenosis or regurgitation, a heart team evaluation note, and documentation that catheter-based alternatives were considered. Check individual payer policies, as requirements change annually.

Documentation checklist for the operative record:

• Open sternotomy approach confirmed
• Cardiopulmonary bypass established and discontinued
• Valve type explicitly stated as mechanical or bioprosthetic (name the specific prosthesis)
• Native valve excised
• Prosthesis size recorded
• Any concurrent procedures (CABG, myectomy) separately described

Global period: CPT code 33405 carries a 90-day global period. Routine post-operative office visits within those 90 days are included in the global package and cannot be billed separately. Separate billing is permitted in four situations:

• Modifier 24: an unrelated E/M service
• Modifier 78: a return to the operating room for a complication
• Modifier 58: a staged procedure planned at the time of the original surgery
• Modifier 79: an unrelated procedure or service by the same physician during the postoperative period

The global period starts the day after surgery, not the day of. Confirm that your billing system applies the correct start-date logic before auto-generating post-op visit claims. A structured superbill with the global-period end date captured reduces inadvertent post-op billing errors.

Common denial reasons for CPT code 33405 and how to resolve them

Denials on 33405 claims are disproportionately expensive relative to typical outpatient codes because the professional fee and associated claims represent high-dollar reimbursement. Identifying the most common denial patterns before submission is far more efficient than working rejections after the fact.

• Wrong code selected. A homograft valve was implanted, but 33405 was billed instead of 33406. Or a stentless tissue valve was used and 33410 was the correct code. Resolution: review the operative note for explicit valve-type language before billing.
• Missing prior authorization. Claim submitted without an auth number for a commercial or Medicare Advantage plan that requires one. Resolution: verify PA requirements per plan before scheduling; document the auth number on the claim form.
• Medical necessity not established. No echocardiogram on file confirming severe valvular disease. Resolution: attach the echo report to the prior auth request and ensure it is in the medical record before claim submission.
• Unbundled cardiopulmonary bypass. CPB billed as a separate line item. Resolution: remove the CPB charge; it is always bundled into 33405 per NCCI edits.
• Modifier omitted on co-surgery claim. Two surgeons billed 33405 without appending modifier 62. Resolution: both surgeons append 62; each submits their own claim with a distinct operative note documenting their role.
• Incorrect place of service. POS 11 (office) was used instead of 21 (inpatient) or 22 (outpatient hospital). 33405 is performed exclusively in a hospital setting. Resolution: correct the POS to 21 or 22 before resubmitting.
• Diagnosis lacks specificity. A non-specific cardiac diagnosis was used instead of the appropriate valvular ICD-10-CM code. Resolution: use the most specific diagnosis code supported by the clinical record.

Tracking denial patterns across 33405 claims shows billing teams whether errors are coder-driven (wrong code) or documentation-driven (missing records).

Pabau, the practice management platform we build, receives electronic remittance advice (ERA) through its Claim.MD integration. Its denial management workflow flags the claim adjustment reason code (CARC) on each ERA, so teams can fix root causes. Our clean claim guide covers how submissions pass clearinghouse edits on the first attempt.

How Pabau reduces denials on CPT code 33405 claims

Cardiac surgery billing teams often check eligibility in a payer portal, submit through a separate clearinghouse, and reconcile remittances in a spreadsheet. On a 33405 claim, each handoff lets a wrong valve code, a missing auth number, or an unbundled bypass line slip through.

Pabau connects to Claim.MD, so real-time eligibility checks, claim submission, and electronic remittance reconciliation happen in one workflow. Through its single-workflow claims management, Pabau submits CMS-1500 and 837P claims to thousands of US payers.

Denials come back with their reason codes attached to the claim. That lets your team tell a coding error from a documentation miss and fix the surgeon’s dictation habit, not just the one claim.

Streamline cardiac surgery billing with Pabau

Pabau connects to Claim.MD to submit, track, and reconcile high-value claims like 33405. Eligibility checks, remittances, and denial tracking sit in one platform.

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Conclusion

On a 33405 claim, the operative note decides the payment. If it names the open approach, the bypass, and the prosthesis type, the code will hold up in review. If any of the three is missing, query the surgeon before the claim goes out.

That pre-bill check slows submission slightly on every open valve case. It still costs far less than appealing a denied cardiac surgery claim, and it teaches surgeons which details their dictation must carry.

Book a demo to see how Pabau keeps 33405 claims, eligibility checks, and remittances in one traceable workflow.

Continue your research

Need to understand how claim denials are categorized? Denial codes in medical billing explains CARC and RARC codes returned on remittances for high-value surgical claims.

Preparing a clean submission for a complex cardiac surgery claim? How the 837P file works walks through the electronic transaction format used to submit professional claims like 33405 to payers.

Looking for a broader overview of surgical billing compliance? What is medical billing covers the end-to-end workflow from code selection through payment posting.

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