CPT code 93571 – Coronary flow reserve measurement

Key takeaways

CPT 93571 is an add-on code for coronary flow reserve measurement, such as FFR, in the first coronary vessel or graft studied.

Each additional vessel studied in the same session is reported with add-on code 93572, one unit per vessel, never with a second unit of 93571.

Both codes need a qualifying primary coronary angiography or PCI code on the same claim, or the add-on line is denied.

The physician in a hospital cath lab bills 93571-26, which carries 2.78 RVUs and pays about $92.85 nationally at the 2026 non-QP conversion factor.

Claims software such as Pabau keeps the cath report, claim and remittance in one record. Your coders still choose and pair the codes.

CPT code 93571 reports coronary flow reserve in the first vessel

CPT code 93571 reports intravascular Doppler velocity and/or pressure-derived coronary flow reserve measurement in the first coronary vessel or graft studied during coronary angiography. The American Medical Association lists it as an add-on code, marked with a “+” in the CPT code book. It never stands alone on a claim.

The 2026 AMA descriptor has three parts:

• Service: “Intravascular Doppler velocity and/or pressure derived coronary flow reserve measurement (coronary vessel or graft)”
• Setting: “during coronary angiography including pharmacologically induced stress, when performed”
• Scope: “initial vessel (List separately in addition to code for primary procedure)”

The words “when performed” are new for 2026, according to the ACC coding overview for 2026. Earlier editions described pharmacologic stress as part of the service without that qualifier.

In practice, the code covers wire-based coronary physiology. The two common methods are a pressure wire, which measures fractional flow reserve (FFR) across a stenosis, and a Doppler-tipped wire, which measures flow velocity.

CPT 93571 vs 93572: initial vessel and each additional vessel

CPT 93571 and 93572 split one service by vessel count. The first vessel or graft studied goes on 93571, and every further vessel studied in the same session goes on 93572.

• One unit per vessel: A vessel counts once, however many readings are taken in it. FFR and a resting index in the same artery are still one unit.
• Grafts count as vessels: The descriptor says “coronary vessel or graft,” so a bypass graft studied after a native artery is reported with 93572.
• 93572 depends on 93571: A claim that carries 93572 without 93571 has no initial vessel, and payers reject the additional-vessel line.
• Unit limits: Check the current CMS medically unlikely edit (MUE) values before sending a claim that lists several 93572 units.

There is no CPT 93570 in this family. Some billing references still teach a 93570 initial-vessel code, and a claim built on that pairing fails at the first edit.

Primary procedure codes that 93571 must be reported with

CPT 93571 is paid only when a qualifying primary coronary angiography or PCI code appears on the same claim. The CPT parenthetical before 2026 listed 92920, 92924, 92928, 92933, 92937, 92941, 92943, 92975, 93454-93461, 93563 and 93564.

Two of those parents are add-on codes themselves. When 93563 or 93564 anchors the claim, its own primary congenital catheterization code must be present too.

CPT 2026 reshaped the PCI family. It deleted the branch add-on codes 92921, 92925, 92929, 92934, 92938 and 92944, plus thrombolysis code 92975, and folded branch work into the base codes.

It also added 92930 for multiple lesions or a bifurcation in one major artery, and 92945 for a combined antegrade and retrograde CTO approach. Check the 2026 CPT parenthetical before pairing 93571 with either new code, and never with a deleted one.

What CPT 93571 includes and what you report separately

CPT 93571 includes the wire placement, the physiologic recording and interpretation in the first vessel, and any pharmacologic stress used to reach hyperemia. Common methods reported under the code include:

• Fractional flow reserve (FFR): The ratio of distal coronary pressure to aortic pressure under maximal hyperemia, usually induced with adenosine.
• Resting pressure indices: Instantaneous wave-free ratio (iFR), resting full-cycle ratio (RFR) and resting Pd/Pa, which need no stress agent.
• Doppler-derived coronary flow reserve: The change in coronary flow velocity from rest to hyperemia, measured with a Doppler wire.

In 2019, the ACC and SCAI advised appending modifier 52 to 93571 or 93572 when no stress agent was given. The descriptor then included stress without a qualifier. The 2026 “when performed” wording changes that premise, so confirm with your MAC and main payers whether they still expect modifier 52 for resting indices.

These services are not part of 93571 and are reported on their own lines when performed:

• Intravascular ultrasound (IVUS) or optical coherence tomography (OCT), reported with add-on codes 92978 for the initial vessel and 92979 for each additional vessel.
• The coronary angiography itself, which belongs to the primary catheterization code.
• Physiology in a second or third vessel, which goes on 93572.

Documentation that supports a 93571 claim

A procedure note supporting CPT 93571 has to show which vessel was measured, how, and why. Missing vessel detail is one of the most common reasons these lines fail clean claim submission review.

• Vessel identification: Name each artery, segment or graft measured, such as “mid LAD” or “SVG to RCA.” A note that says “multiple vessels” cannot support separate 93571 and 93572 lines.
• Order of vessels: Record which vessel was studied first, since that vessel maps to 93571.
• Method: State whether FFR, iFR, RFR, resting Pd/Pa or Doppler flow reserve was used in each vessel.
• Numeric result: Record each value, such as “FFR 0.78,” in the body of the note.
• Stress agent, when used: Document the drug, dose and route, such as intravenous or intracoronary adenosine.
• Clinical indication: Explain why physiology was needed in that vessel and how the result shaped the treatment decision.
• Signature: The performing cardiologist signs and dates the report.

Modifiers on CPT 93571 follow its professional and technical split

CPT 93571 has a professional component/technical component (PCTC) indicator of 1 in the 2026 CMS RVU file, so modifiers 26 and TC apply. Its global period is ZZZ, which ties it to the global period of the primary procedure.

• Modifier 26 (professional component): The usual claim for a cardiologist working in a hospital cath lab. Medicare prices 93571-26 nationally.
• Modifier TC (technical component): Carrier-priced in the 2026 physician fee schedule, so the MAC sets the amount. In a hospital outpatient department, the technical side falls under OPPS rather than the physician fee schedule.
• No modifier (global): Also carrier-priced. It applies only where the billing physician owns the equipment and staff, such as an office-based lab.
• Modifier 51: Never used. The RVU file sets the multiple procedure indicator to 0, so no multiple-procedure reduction applies.
• Modifier 52: Historically advised for resting indices without a stress agent. Confirm current payer policy before using it after the 2026 descriptor change.
• Modifier 59 or X{EPSU}: Not a routine part of 93571 billing. Use one only when an NCCI edit applies and the documentation supports a distinct service.

Hospital outpatient departments have historically seen 93571 packaged into the primary procedure payment under OPPS (status indicator N). Check the current OPPS Addendum B before coding the facility claim.

2026 Medicare payment for CPT 93571 and 93572

The 2026 physician fee schedule prices 93571-26 at 2.78 total RVUs in both facility and non-facility settings. CMS publishes two conversion factors for 2026: $33.5675 for qualifying APM participants (QPs) and $33.4009 for all other clinicians.

These are national unadjusted amounts from the CMS RVU26D file (October 2026 release). Your MAC adjusts them by the geographic practice cost index (GPCI) for your locality, which you can check in the CMS Physician Fee Schedule lookup.

The global and TC rows carry no national rate, because both are carrier-priced. Commercial contracts usually pay a negotiated percentage of Medicare, so check each payer schedule.

Billing arithmetic for a multi-vessel physiology study

Vessel count sets the units, and the order of study sets which code each vessel gets. Consider a diagnostic left heart catheterization with FFR in the LAD, then the circumflex, then a vein graft.

• Line 1: 93458-26 for the diagnostic catheterization.
• Line 2: 93571-26 × 1 for the LAD, the first vessel studied.
• Line 3: 93572-26 × 2 for the circumflex and the graft.

Line 1 changes if the grafts are imaged as well. Bypass graft angiography during the same left heart catheterization makes 93459 the parent code instead of 93458.

At the 2026 non-QP rate, the physiology lines total $92.85 plus $146.96, or $239.81 before GPCI. The breakdown below lines up each vessel with its code and payment.

Coding that session as 93571 × 3 inflates the claim and draws a unit-limit denial on all three lines.

The same logic applies when FFR guides a same-session PCI. The physiology add-ons can attach to the diagnostic angiography or the PCI code, but each vessel still appears once.

Same-day diagnostic angiography is separately reportable with PCI only under set conditions. Examples are no prior study, or a change in the patient’s condition. Medicare claims for that case usually carry modifier 59 or XU on the diagnostic code.

In an interventional program, the pre-procedure checklist should already record which parent code the physiology lines will attach to.

Medical necessity and coverage for CPT 93571

Medicare covers CPT 93571 when the measurement is reasonable and necessary to decide on treatment for a specific stenosis. The note has to connect the measurement to that decision, and the claim’s ICD-10-CM diagnosis codes have to show the coronary disease behind it.

The typical indication is an angiographically intermediate stenosis where visual grading alone cannot settle whether to revascularize. FFR of 0.80 or lower and iFR of 0.89 or lower are the ischemic thresholds most labs use.

Chronic coronary atherosclerosis is reported from the I25.1 subcategory, and I25.10 covers native-artery disease without angina.

• Supported: An intermediate lesion in a patient with symptoms or ischemia, where the result decides between PCI and medical therapy.
• Supported: Multivessel disease where physiology decides which lesions to treat.
• Hard to support: Physiology in a vessel with no documented stenosis, or one with no treatment decision riding on the result.
• Not billable: Measurements done only for research, with no clinical decision attached.

MAC policies differ in how much documentation they expect. Search the Medicare Coverage Database for your MAC’s local coverage determinations and billing articles before relying on a single template.

Common CPT 93571 denials and how to prevent them

Most 93571 and 93572 denials trace back to the code pairing or to vessel documentation. Strong denial management workflows catch both before the claim leaves the practice.

How claims management software keeps 93571 claims moving

Many cath lab teams retype the procedure report into a billing system. When a physiology line comes back short, they chase the payer by phone. Each handoff risks losing the vessel order or the numeric result.

Pabau keeps the procedure note, the charges and the claim on one patient record. Its payment-tracking claims software pulls the data already on that record into a pre-filled claim and sends it through Claim.MD. Status updates and remittances then come back to the same record.

• Structured procedure notes: Custom forms can require vessel, method and value fields, so the note always carries what a 93572 line needs.
• Eligibility checks: Coverage is confirmed before the procedure, not after the denial.
• Claim tracking: Each claim shows its status, so a rejected add-on line is visible within days.
• Remittance matching: Payments post against the claim lines they pay, and short-paid lines stand out.

Pabau does not choose codes or check add-on pairings for you. Your coders still decide between 93571 and 93572 and attach them to the right parent. A consistent superbill then carries those choices from the cath lab to the claim unchanged.

Keep cath lab claims moving to payment

Pabau keeps procedure notes, claims and remittances on one record, submits through Claim.MD, and tracks every claim to payment. See how it fits a cardiology billing team.

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Conclusion

Get the vessel count right and CPT 93571 is one of the simpler add-ons in cardiology. The first vessel goes on 93571, each further vessel on 93572, and both ride on a 2026-valid parent code.

The riskier work in 2026 sits around the code. PCI branch codes are gone, and the descriptor now says “when performed.” Old habits, such as modifier 52 or a phantom 93570, need checking against current payer rules.

Audit your charge sheet and note template against those changes before your next multi-vessel case. Book a demo to see how Pabau keeps cath lab notes, claims and payments on one record.

Continue your research

Need to understand how claims move from cath lab to payer? Medical claims clearinghouse overview explains how electronic claim submission and ERA processing work from charge capture to payment posting.

Want to reduce denial rework time across your cardiology team? Denial codes in medical billing breaks down the most common CARC denial codes and the corrective workflows that resolve them fastest.

Looking for guidance on insurance credentialing before billing intervention codes? Getting credentialed with insurance companies walks through the enrollment steps that determine whether a claim pays or denies at the payer level.

Coding the noninvasive study that came before the cath lab? CPT code 75574 walks through cardiac CT angiography billing for the same patient group.

Billing the surgical route when physiology points to bypass? CPT code 33533 explains how a single arterial coronary bypass graft is coded and paid.

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