Aortic Stenosis ICD-10: The FY2026 Coding, Documentation and Denial Guide

Quick answer

In medical billing, the aortic stenosis ICD-10 code is I35.0, nonrheumatic aortic (valve) stenosis, which covers degenerative and calcific narrowing of the aortic valve that isn’t caused by rheumatic fever.

Alternative aortic stenosis ICD-10 codes apply depending on what caused the disease, and on whether regurgitation appears alongside the narrowing.

There’s no separate severe aortic stenosis ICD-10 code. I35.0 carries mild, moderate, and severe disease alike. Severity still decides whether the payer pays the claim.

Six facts that shape every valve claim

• I35.0 is the billable FY2026 code for nonrheumatic aortic stenosis at any severity.
• I35.2 applies when the record documents stenosis and insufficiency together, not I35.0 plus I35.1.
• I06.0 replaces I35.0 when the physician documents rheumatic origin.
• Q23.81 goes alongside I35.0 when the echo shows a bicuspid valve.
• Z95.2, Z95.3, and Z95.4 are three separate post-replacement status codes, not two.
• CMS issues its final TAVR coverage decision on September 13, 2026.

The Complete FY2026 Aortic Valve ICD-10 Code Set

Which Code Applies to Which Presentation

Three questions decide the aortic stenosis ICD-10 code you assign. What caused the disease, whether regurgitation sits alongside the stenosis, and whether the obstruction sits at the valve or above or below it. Get those three answers from the chart and the code follows. Miss one and you’re guessing. For the procedure side of the same encounter, our cardiology CPT codes guide maps the diagnostic and interventional codes that pair with these diagnoses.

The table below covers the full aortic valve family, including two codes most billing references skip.

Why Excludes2 Doesn’t Mean What Most Coders Think

The I35 category carries Excludes2 notes pointing to I08, Q23.0, Q23.1, I06, and I42.1. Excludes2 means the excluded condition isn’t part of the coded condition. A patient can carry both, and you can report both. Most coders read it the opposite way and drop a legitimate second code. The FY2026 ICD-10-CM Official Guidelines set out the convention.

One more annotation belongs on your desk. I35.0 carries a Code Also instruction pointing to Q23.81. When the echo names a bicuspid valve, both codes go on the claim.

On the facility side, I35.0 groups to MS-DRG 306 and 307, cardiac congenital and valvular disorders with and without a major complication. Valvular heart disease ICD-10 assignment drives that split before any procedure code enters the picture.

Why There Is No ICD-10 Code for Mild, Moderate, or Severe Aortic Stenosis

ICD-10-CM has no severity-specific code for nonrheumatic aortic stenosis. Mild, moderate, severe, and very severe all take I35.0. Searching for a moderate aortic stenosis ICD-10 code returns the same code as severe, because the classification doesn’t encode hemodynamic severity at all.

What Severity Decides

Severity doesn’t change the diagnosis code. It decides whether the payer accepts medical necessity for the echo, the catheterization, and the valve replacement. It drives the CMS coverage criteria for TAVR. It shifts DRG assignment once complications enter the picture.

A note reading “aortic stenosis” with no severity attached gives your coder nothing to defend on appeal. That gap costs more than a miscoded claim, because the appeal fails on the record rather than on the code. Practices that keep hitting this pattern usually need specialty cardiology coding support rather than another round of coder training.

What the Payer Sees Instead

Payers read the echo numbers. Map the report to a severity statement using the American College of Cardiology and American Heart Association thresholds below, then make sure the physician’s impression matches what the measurements show.

That last row is where a mild aortic stenosis ICD-10 assumption gets a practice into trouble. A patient with a valve area at 0.8 cm2 and a gradient of 30 mmHg has severe disease with a low gradient, not moderate disease. The coder can’t make that call. The physician has to.

Evidence backs this up. A study in Circulation: Cardiovascular Quality and Outcomes compared Medicare claims against paired echocardiograms and found that I35.0 identified fewer than half of the patients who had aortic stenosis on the echo. Among patients carrying the code, roughly 40% had severe disease while the rest had mild, moderate, or none. Claims can’t distinguish severity, per the NIH study on ICD-10 claims accuracy. Documentation protects the claim. Code selection alone doesn’t.

Rheumatic Versus Nonrheumatic Aortic Stenosis: Which Code Applies

Nonrheumatic disease is degenerative or calcific narrowing with no rheumatic cause, and the aortic stenosis ICD-10 code for it is I35.0. Rheumatic aortic stenosis follows rheumatic fever and takes I06.0. When the record documents stenosis and insufficiency together, the nonrheumatic combination code is I35.2 and the rheumatic one is I06.2.

The Documentation Rule That Decides It

Read the echo impression before you read the assessment. Rheumatic disease fuses the leaflet edges and usually damages the mitral valve too. Degenerative disease calcifies from the center outward with no fusion, and it usually shows up alone in an older patient. Bicuspid disease presents one to two decades earlier than either.

Now the part that catches practices out. CMS guidance for cardiology coding warns that the classification treats heart valve disease as rheumatic unless the record notes otherwise, per the CMS ICD-10 code files. When a physician writes only “aortic stenosis,” your coder works against a default that pushes the claim toward the wrong code family.

What Happens When Etiology Is Missing

Query before you code. A compliant query offers the options without steering the answer, so keep it neutral and let the physician pick.

Sample query text: “The record documents aortic stenosis. Based on your clinical judgment and the documentation available, can the etiology be further specified? Options: rheumatic, degenerative or calcific, congenital, other (please specify), or unable to determine.”

One more check before the claim goes out. When the mitral valve shows disease alongside the aortic valve, look at the I08 combined-valve category before assigning two separate codes. The same discipline applies across the cardiology diagnosis set, which our atrial fibrillation ICD-10 guide covers for rhythm coding.

Aortic Sclerosis Versus Aortic Stenosis: I35.8 or I35.0

Aortic sclerosis is thickening and calcification of the valve leaflets without hemodynamically significant obstruction, and it codes to I35.8. Aortic stenosis involves obstruction and codes to I35.0. The dividing line is hemodynamic, not descriptive. It comes from the echo, not from the word the physician chose.

The Velocity Threshold That Separates Them

Sclerosis shows a peak jet velocity below 2.0 m/s with no meaningful gradient across the valve. Stenosis begins at 2.0 m/s or above with a measurable gradient. A small percentage of sclerosis cases progress to stenosis each year, so the same patient can carry I35.8 in one year and the aortic stenosis ICD-10 code the next without anyone having miscoded either encounter.

Why the Same Term Appears Under Two Codes

Code databases list aortic valve sclerosis as an approximate synonym under both I35.0 and I35.8. Two coders reading the same index entry reach different answers, and the practice ends up submitting the aortic valve sclerosis ICD-10 assignment inconsistently across months. The synonym list is an index aid. It isn’t a coding instruction. The hemodynamic finding decides.

A second trap sits nearby. Aortic valve calcification without stenosis is I35.8, not I70.0. I70.0 covers atherosclerosis of the aorta, which is a different anatomical structure, and the alphabetic index entry for calcification of the aorta leads straight to it. Practices billing calcium scoring alongside valve studies hit this often, and our coronary calcium scoring billing guide covers the procedure side of that encounter.

When the note says sclerosis but the echo shows velocity at or above 2.0 m/s, query before you code. Assigning the aortic valve sclerosis ICD-10 code against an echo that shows obstruction is the version of this error that surfaces in audits.

Conditions That Look Like Aortic Stenosis but Take a Different Code

Not every obstruction to left ventricular outflow is valvular aortic stenosis. Obstruction above the valve is supravalvular and takes Q25.3. Obstruction below the valve is subvalvular, taking a congenital code, or I42.1 when septal hypertrophy causes dynamic obstruction. In both cases the aortic valve itself can be structurally normal.

Differential diagnosis and code selection are the same exercise. The table below separates the conditions that share a clinical picture with aortic valve stenosis ICD-10 assignment.

Obstruction Above or Below the Valve

The Excludes2 note for I42.1 matters here. A patient with hypertrophic cardiomyopathy and valvular stenosis can carry both codes. Coding one and dropping the other loses either the DRG weight or the clinical picture, and neither loss shows up until an auditor asks.

Supravalvular stenosis stays in the Q chapter regardless of the patient’s age. Congenital anomalies get coded at any age when they still affect management, so a 58-year-old with supravalvular narrowing takes Q25.3 rather than an aortic stenosis ICD-10 code from the I35 family.

Mitral, Tricuspid, and Pulmonary Valve ICD-10 Codes

The three questions that govern aortic coding govern every other valve. Cause, whether stenosis and insufficiency coexist, and whether more than one valve is involved. Valvular heart disease ICD-10 assignment works the same way across the whole family, which is why a practice that fixes its aortic documentation usually fixes its mitral documentation at the same time. Our cardiology procedure code reference covers the studies that produce these diagnoses.

Mitral regurgitation ICD-10 and tricuspid regurgitation ICD-10 assignment both turn on the same etiology question you answered for the aortic valve.

One trap sits in the mitral row. Mitral stenosis has a nonrheumatic code, but rheumatic mitral stenosis remains the more commonly documented presentation. Defaulting to the nonrheumatic code out of habit produces the mirror image of the aortic error covered earlier.

When Multiple Valves Are Involved

Aortic and mitral disease appearing together may belong in the I08 category rather than in two separate codes. I08.0 covers rheumatic disorders of both the mitral and aortic valves, I08.2 covers aortic and tricuspid involvement, and I08.3 covers all three.

Assigning two separate valve codes when a combination code exists repeats the error pattern of coding I35.0 plus I35.1 instead of I35.2. Payer audits pick up both patterns, and both look like the same failure to a reviewer: a coder who didn’t check whether a single code already described the finding.

What the Echocardiogram Report Must Document

Your coder picks the code from the physician’s diagnostic statement. Your appeal defends it with the echo measurements. Payers reviewing medical necessity look at the numbers, not the word, which makes the icd 10 code for aortic stenosis only as strong as the report behind it. Component billing on that study has its own rules, covered in our CPT 93306 echocardiogram billing guide.

The Five Values That Support the Code

• Peak aortic jet velocity
• Mean transvalvular gradient
• Aortic valve area, indexed to body surface area where available
• Left ventricular ejection fraction
• Symptom status with NYHA functional class

A complete valve claim needs the peak velocity, the mean gradient, the valve area, the ejection fraction, and the documented symptom status in the record. The first three establish severity. The ejection fraction explains a low gradient when one appears. The symptom status supports intervention, because asymptomatic and symptomatic patients sit on different coverage pathways.

Discordance needs a physician, not a coder. When the valve area points to severe disease and the gradient doesn’t, the record needs the physician’s severity determination rather than your coder’s inference. A dobutamine stress echo often settles it, and our stress echocardiography billing codes guide covers how that study bills.

Poor Documentation Versus Complete Documentation

Weak: “Patient has severe AS.”

Complete: “72-year-old with severe calcific aortic stenosis, nonrheumatic. TTE shows peak velocity 4.8 m/s, mean gradient 52 mmHg, AVA 0.6 cm2, LVEF 55%. NYHA Class III with exertional dyspnea at 20 feet. No rheumatic history. Bicuspid valve noted. Plan: heart team evaluation for TAVR.”

Compare what each one unlocks. The second note names the etiology that justifies I35.0 over I06.0, adds the bicuspid finding that brings in Q23.81, carries the measurements that support medical necessity for the study and the procedure, and states the functional class that supports intervention. The first note supports a code and nothing else.

Pairing Valve Diagnoses With the Right CPT Codes

The diagnosis code establishes why the study happened. The CPT code establishes what happened. A valve claim fails when those two disagree, and that mismatch drives the most common denial on this claim type. Getting the icd 10 code for aortic stenosis right buys you nothing if the procedure code beside it tells a different story. Component rules on these studies are covered in our modifier 26 professional component guide.

Match the study to the diagnosis that justified it, then confirm the record supports both. The aortic stenosis ICD-10 code and the CPT code beside it have to describe the same encounter.

Component Billing on the Echo Claim

Three billing scenarios cover almost every echo claim. When the practice owns the equipment and reads the study, bill globally with no modifier. When your physician reads a study performed somewhere else, append modifier 26. When the facility owns the equipment and a separate physician reads it, the facility appends TC.

Billing globally when your physician only performed the interpretation produces an unbundling denial. Repeat it across a month of volume and it becomes an audit flag rather than a denial. The catheterization side carries its own component rules, covered in our coronary angiography billing rules guide.

One point carries forward from the documentation section. Dobutamine stress echo exists to resolve low-gradient cases, so the diagnosis on that claim has to show why the resting study fell short. Submitting it with the same diagnosis as the resting echo invites a medical necessity review.

Coding Valve Status After TAVR or SAVR: Z95.2, Z95.3 and Z95.4

After aortic valve replacement, a status code showing the prosthesis replaces the native disease code. Three status codes exist. Z95.2 covers a prosthetic heart valve, Z95.3 covers a xenogenic heart valve, and Z95.4 covers other heart-valve replacement. Most published guidance on the aortic valve replacement ICD-10 question names only two of them.

Three Status Codes, Not Two

Here is where honesty serves you better than a rule. The descriptors are clear, but application varies by facility. Most bioprosthetic surgical and transcatheter valves are xenogenic by construction, and no single CMS instruction maps a given TAVR device to one specific code. Anyone who tells you the s/p TAVR ICD-10 answer is settled is overstating what the guidance says.

Pick one convention, write it into your coding policy, and apply it the same way every time. Consistency survives an audit. An inconsistent icd 10 code for TAVR status across a quarter of claims doesn’t, and it corrupts your registry data along the way. Because these procedures happen inpatient, the POS 21 inpatient hospital rules apply to the professional claims alongside them.

When a Complication Code Applies Instead

The Z95 category carries a Type 2 Excludes note pointing to the T82 complication codes. Both can go on the claim together, so a patient with a prosthetic valve and a prosthetic valve complication gets the status code and the complication code.

• T82.01 covers breakdown of a heart valve prosthesis
• T82.02 covers displacement
• T82.03 covers leakage
• T82.857 covers stenosis of a cardiac prosthetic device
• T82.6 covers infection due to a cardiac prosthetic device

Each T82 code needs a seventh character for initial encounter, subsequent encounter, or sequela. Dropping it produces a rejection that looks like a coding error and reads like carelessness to a reviewer.

Valve-in-valve procedures need both halves of the story. Report the original valve status alongside the acute indication that justified reintervention. The icd 10 for aortic valve replacement history doesn’t disappear because a second device went in, and the structural deterioration that drove the second procedure needs its own code.

Where the Claim Is Billed Changes What Gets Paid

A valve patient admitted for management and a valve patient admitted for replacement produce completely different payment paths from the same aortic valve stenosis ICD-10 code. The diagnosis doesn’t change. The money does.

Medical DRG Versus Procedural DRG

When aortic stenosis is the principal diagnosis and the admission ends without a valve procedure, the case groups to the medical DRG family for cardiac congenital and valvular disorders, split by whether a major complication or comorbidity is present. When a replacement happens, the procedure drives the grouping instead. Transcatheter and open surgical approaches map to different DRG families carrying different payment weights.

Device cost trips practices up. Inpatient device cost sits inside the DRG payment, so no separate device line goes on the claim. In the hospital outpatient setting under OPPS, device billing follows different rules that depend on current pass-through status, and those assignments change annually. Verify them each year rather than carrying last year’s logic forward. Our hospital revenue cycle services team handles this reconciliation for facilities billing both streams.

Approach mismatch triggers manual review. Pairing a percutaneous procedural code with a surgical approach code, or the reverse, flags the claim on approach mismatch. Both the icd 10 for aortic valve replacement and the procedure code have to describe the same operation, and our combined heart catheterization billing guide covers the diagnostic studies that precede it.

Medicare Coverage for TAVR and the September 2026 Decision

Coverage for valve replacement runs through a national coverage determination. The aortic stenosis ICD-10 code is what connects the clinical picture to that coverage, which makes code selection a coverage decision rather than a clerical one.

What the Current Coverage Determination Requires

CMS ties coverage to symptomatic severe aortic stenosis ICD-10 documentation, an FDA-approved indication, and conditions including heart team evaluation, per the current TAVR coverage determination. Coverage with Evidence Development attaches participation requirements to payment, which means your billing team carries obligations beyond submitting a clean claim. The aortic valve replacement ICD-10 assignment has to line up with those conditions before the claim goes out.

Regional rules layer on top of the national ones. Our how LCDs set coverage guide explains how a Medicare Administrative Contractor narrows a national policy for your jurisdiction.

What Changes if the Proposal Is Finalized

CMS issued a proposed decision memo reconsidering the TAVR national coverage determination. The proposal would remove Coverage with Evidence Development requirements for patients with symptomatic severe aortic stenosis, and would add coverage for asymptomatic severe aortic stenosis under Coverage with Evidence Development, per the CMS proposed TAVR decision memo. The public comment period closed on July 15, 2026.

CMS lists an expected completion date of September 13, 2026 for the TAVR national coverage determination reconsideration, per the CMS TAVR coverage tracking sheet. That date sits weeks away, and the workflow changes land the moment the final memo publishes.

Three things need attention before then:

• Update prior authorization workflows before the effective date. Our prior authorization workflow guide covers the sequence.
• Add the asymptomatic pathway to documentation checklists, so referring cardiologists know what the record needs.
• Review any billing convention tied to Coverage with Evidence Development, because the icd 10 code for TAVR claims built around those requirements may need rebuilding.

The American College of Cardiology analysis covers what the proposal means for program operations. If your team is carrying the authorization load for a structural heart program, prior authorization support takes the verification work off the front desk before the rules shift.

Status as of publication. This section reflects the proposed decision memo. We will update it when CMS issues the final decision.

Why Valve Claims Get Denied, and How to Fix Each One

Valve claims fail in predictable ways. Each pattern has a specific fix, and the fix starts in the record rather than in the appeal. Five denial codes account for most of what lands in a cardiology aging report tied to the aortic stenosis ICD-10 family.

The Five Denials That Hit Valve Claims

CO-11 and CO-50 together drive most valve denials, and they have different roots. Our CO-11 diagnosis mismatch denials guide covers the pairing problem. The CO-50 medical necessity denials guide covers the documentation problem. Practices tracking denial patterns across specialties can compare against the most common denial codes by volume.

The aortic regurgitation ICD-10 codes deserve a separate look here. Coverage lists for echo studies often name specific valve codes, and a regurgitation code submitted against a policy written for stenosis triggers CO-11 even when the study was appropriate.

Cutting the Unspecified Code Rate

I35.9 exists for the rare case a physician can’t specify further. Teams use it as a default instead. Audit the ratio of I35.9 to specific I35 codes across a quarter, then treat a rising ratio as a documentation problem rather than a coder problem, because a coder can’t specify what the physician didn’t write.

Remember what the claims research showed. Claims data already fails to capture severity for nonrheumatic aortic valve stenosis ICD-10 assignment. An unspecified code compounds a gap that exists before your coder touches the chart.

If valve denials are stacking up faster than your team can work them, that’s usually a documentation pattern rather than a coder problem. Our cardiology denial recovery team works each denial by root cause, starting from the code on the remittance advice. We can look at the pattern with you.

Which ICD-10 Code Set Is in Effect Right Now

The FY2026 ICD-10-CM code set took effect October 1, 2025 and governs claims through September 30, 2026. FY2027 takes effect for discharges and encounters on or after October 1, 2026. CMS also publishes updates on a second cycle during the year, so check the current release before assuming an annual file is the latest one, per the CMS MLN Connects update notice.

Coding an aortic stenosis ICD-10 claim against the wrong window produces a rejection that looks like a coding error and is a calendar error. It bites hardest on claims submitted near the boundary, and on corrected claims for older dates of service, where the code file in your system may no longer match the date the service happened.

What to Audit Before October 1

• Pull the unspecified code ratio for I35.9 against the specific I35 codes
• Confirm the code file version loaded in your practice management system
• Check payer coverage lists that name specific diagnosis codes, because those lists update separately
• Schedule the update before the boundary rather than after the first rejection

Valvular heart disease ICD-10 assignment shifts less often than procedure coding does, which is exactly why the annual check gets skipped. Our coding audit for cardiology team runs this review against current files before the boundary rather than after the denials arrive.

Aortic Stenosis ICD-10 Questions Coders Ask Most

What is the ICD-10 code for aortic stenosis?

The aortic stenosis ICD-10 code is I35.0, nonrheumatic aortic (valve) stenosis. Three alternatives displace it. I06.0 applies when the record documents rheumatic origin. Q23.0 applies when the stenosis is congenital. I35.2 applies when stenosis and insufficiency appear together in the same encounter. When the echo documents a bicuspid valve, add Q23.81 alongside I35.0 rather than choosing between them, because the I35.0 entry carries a Code Also instruction pointing to it.

Is there a different ICD-10 code for severe aortic stenosis?

No. ICD-10-CM has no severity-specific code for nonrheumatic aortic stenosis. Mild, moderate, and severe disease all take I35.0, so searching for a moderate aortic stenosis ICD-10 code or a mild aortic stenosis ICD-10 code returns the same answer. Severity still matters. It determines whether the payer accepts medical necessity for the echo, the catheterization, and the valve replacement, and it drives CMS coverage criteria for TAVR. Document the measurements even though the code doesn’t change.

Do you code I35.0 and I35.1 together when stenosis and regurgitation are both present?

No. ICD-10-CM provides I35.2, nonrheumatic aortic valve stenosis with insufficiency, as a combination code for that presentation. Coding conventions direct you to the single code when one exists that describes both findings. Assigning I35.0 plus I35.1 instead reports the same clinical picture twice and surfaces in payer audits as a specificity failure. The rheumatic equivalent is I06.2, which follows the same rule when the record documents rheumatic origin.

What ICD-10 code do you use after TAVR?

Report a status code from the Z95 family showing the prosthesis is present. Z95.2 covers a prosthetic heart valve, Z95.3 covers a xenogenic heart valve derived from animal tissue, and Z95.4 covers other heart-valve replacement. The native disease code generally stops once the valve is replaced, unless native disease persists elsewhere. Facility convention varies on which code fits a given transcatheter device, so choose one convention, document it in your coding policy, and apply it consistently. Consistency is what survives an audit.

When do you add Q23.81 for a bicuspid aortic valve?

Add Q23.81 whenever the echo documents a bicuspid valve alongside stenosis. The I35.0 entry carries a Code Also instruction pointing to it, because the bicuspid valve is the underlying cause and the stenosis is the current lesion. Both go on the claim. Q23.81 is the bicuspid aortic valve ICD-10 code specifically. Other subdivisions under Q23.8 cover different congenital malformations of the aortic and mitral valves, so verify the subdivision against the current tabular list rather than relying on a secondary source.

Getting Valve Claims Right the First Time

The code is the easy part. Documentation is what gets it paid, and two dates on the calendar decide what your workflow needs to look like by autumn: the CMS coverage decision on September 13, 2026, and the annual code update on October 1.

Cardiology coding punishes small documentation gaps harder than most specialties, because the measurements that justify the claim sit in a report your coder didn’t write. If you want a second set of eyes on how your valve claims are being coded and where they’re leaking, that’s the kind of thing our cardiology billing team looks at every day.