Skip to content
How It Works
Explore
Ask a Question Resources Pricing
Who It's For
Patients
Decode results, prep for appointments, weigh options.
Caregivers & advocates
Carry the research load for someone you love.
Providers & clinicians
Resources for patients in your practice.
Log In Ask a Question
PubMed This is a summary of 20 peer-reviewed journal articles Updated
Cardiology

Understanding Mitral Valve Stenosis

At a Glance

Mitral valve stenosis is a physical narrowing between the left atrium and left ventricle, often caused by rheumatic scarring or age-related calcification. An echocardiogram measures the valve opening and pressure to guide monitoring and decisions about procedures.

Learning you have a heart valve condition can feel scary, but understanding how your heart’s mechanics work is a powerful first step in taking control of your care. The mitral valve serves as a one-way door between the upper left chamber of your heart (left atrium) and the lower left chamber (left ventricle). In a healthy heart, this door swings wide open to let oxygen-rich blood flow through and then snaps shut to prevent blood from leaking backward. Mitral stenosis is a condition where this door becomes stiff, thickened, or narrowed, creating a mechanical obstruction that makes it harder for your heart to move blood forward [1][2].

This is fundamentally a mechanical problem. While your doctor may prescribe medications to manage symptoms like fluid buildup or a rapid heart rate, it is important to understand that no pill can “dissolve” the scar tissue or “melt away” the calcium narrowing the valve [3][4]. To restore flow, the “door” itself must eventually be addressed through a medical procedure.

How Rheumatic Fever Changes the Heart

For many people, mitral stenosis is the long-term result of rheumatic fever, a condition that may follow a group A streptococcal “strep throat” infection during childhood. It is important to know that most strep infections do not lead to rheumatic fever, and the cause cannot always be determined retrospectively. This is caused by a process called molecular mimicry, where your immune system, while trying to fight off the bacteria, accidentally begins to attack the similar-looking proteins in your own heart valves [5][1].

The damage does not happen all at once. Instead, it follows a specific path over years or even decades:

  • Initial Inflammation: The immune attack causes a “valvulitis,” making the valve leaflets red and swollen [6].
  • The Healing Loop: Even after the infection is gone, the body’s attempt to repair the damage creates a cycle of inflammation and remodeling [7][8].
  • Mechanical Changes: Over time, the edges where the valve leaflets meet (commissures) begin to fuse together, the supporting “strings” (chordae tendineae) shorten and thicken, and the valve becomes a fixed, narrow funnel [1][8].

It can be emotionally difficult to learn that a childhood illness you may barely remember—or an infection that wasn’t treated decades ago—is causing heart issues today. This “latent period” is a well-documented part of the disease, and receiving a diagnosis now is simply the first step in managing that long-term history [7].

Age-Related Calcification (MAC)

While rheumatic disease is the most common cause globally, especially in younger people, a different form of the condition is becoming more frequent in older adults. This is known as Mitral Annular Calcification or MAC [9][10].

MAC is not caused by an infection. Instead, it is an active process where calcium deposits build up in the fibrous ring (annulus) that supports the valve [11]. Think of it like a door frame that has become so encrusted with mineral deposits that the door can no longer swing open fully.

  • Demographics: This type is most common in older adults, particularly women, and those with high blood pressure or chronic kidney disease [9][12].
  • Mechanism: Unlike rheumatic disease, which fuses the tips of the “door,” MAC limits movement by stiffening the base of the valve and pushing into the opening [13].

Measuring the Narrowing

Doctors use specialized imaging, usually an echocardiogram (an ultrasound of the heart), to measure exactly how narrow the valve has become. They look at two main numbers:

  1. Mitral Valve Area (MVA): A measurement of the actual size of the opening. A normal opening is 4 to 6 cm². The disease is usually considered clinically significant or severe when the opening is 1.5 cm² or smaller, though terminology varies by guideline [14][15]. An area around 1.0 cm² often describes very severe disease [14].
  2. Transmitral Gradient: This measures the pressure “backup” behind the valve. A higher gradient means the heart has to work harder to push blood through the narrow gap [14][16].

Because the narrowing is a physical barrier, symptoms often appear when the heart rate increases—such as during exercise—because there isn’t enough time for blood to squeeze through the small opening before the heart beats again [17][18]. Understanding whether your stenosis is caused by rheumatic scarring or age-related calcification is essential, as it helps your care team determine which type of procedure will be most effective for your specific “door” [19][20].

Common questions in this guide

What exactly is mitral valve stenosis?
Mitral valve stenosis is a narrowing of the mitral valve, the one-way opening between the left atrium and left ventricle. The narrowed opening obstructs blood flow and can make the heart work harder, especially when the heart rate rises.
What causes mitral valve stenosis?
Rheumatic fever after a group A strep infection can scar the valve, join its leaflets, and thicken or shorten its supporting cords over many years. In older adults, calcium buildup around the valve, called mitral annular calcification, can also restrict its movement; not every strep infection leads to rheumatic fever.
How do doctors determine how severe my mitral stenosis is?
An echocardiogram measures the mitral valve area and the pressure difference, or gradient, across the valve. A normal opening is about 4 to 6 square centimeters; an area of 1.5 square centimeters or less is often considered clinically significant or severe, while about 1.0 square centimeter indicates very severe narrowing. Exact terminology can vary by guideline.
Can medication cure or open a narrowed mitral valve?
No. Medicines may help control fluid buildup or a rapid heart rate, but they cannot dissolve scar tissue or remove calcium that physically narrows the valve. A procedure may be considered when the narrowing, symptoms, or other health changes warrant it.
Why might shortness of breath or fatigue worsen during exercise?
Exercise makes the heart beat faster, leaving less time for blood to move through the narrowed mitral valve. This can increase pressure behind the valve and contribute to shortness of breath or fatigue. A clinician may use an exercise test if symptoms and resting findings do not match.
What does commissural fusion mean on an echocardiogram?
Commissural fusion means that the places where the mitral valve leaflets meet have become joined by scarring, usually as a result of rheumatic disease. This finding helps doctors understand the valve’s structure and determine whether particular procedures may be suitable.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Was my mitral stenosis likely caused by childhood rheumatic fever or age-related calcification (MAC)?
  2. 2.What is my current mitral valve area (MVA), and how does that affect the classification of my disease severity?
  3. 3.Do my echocardiogram results show 'commissural fusion,' and how does that change my options for treatment?
  4. 4.Are my current symptoms—like shortness of breath or fatigue—explained by the pressure across my valve, or do we need an exercise test to see how the valve behaves when I'm active?
  5. 5.Given that medications cannot open the narrowed valve, what specific milestones or changes in my health would trigger the need for a procedure?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (20)
  1. 1

    Mechanisms of mitral valve development and disease.

    Wang E, Zhou B

    Frontiers in cardiovascular medicine 2026; (13()):1773671 doi:10.3389/fcvm.2026.1773671.

    PMID: 41717582
  2. 2

    Transcatheter Mitral Valve Repair and Replacement: Current Evidence for Intervention and the Role of CT in Preprocedural Planning-A Review for Radiologists and Cardiologists Alike.

    Maggiore P, Anastasius M, Huang AL, et al.

    Radiology. Cardiothoracic imaging 2020; (2(1)):e190106 doi:10.1148/ryct.2020190106.

    PMID: 33778537
  3. 3

    Update on percutaneous mitral commissurotomy.

    Nunes MC, Nascimento BR, Lodi-Junqueira L, et al.

    Heart (British Cardiac Society) 2016; (102(7)):500-7 doi:10.1136/heartjnl-2015-308091.

    PMID: 26743926
  4. 4

    Rheumatic Mitral Valve Stenosis: Diagnosis and Treatment Options.

    Wunderlich NC, Dalvi B, Ho SY, et al.

    Current cardiology reports 2019; (21(3)):14 doi:10.1007/s11886-019-1099-7.

    PMID: 30815750
  5. 5

    Prothymosin Alpha: A Novel Contributor to Estradiol Receptor Alpha-Mediated CD8+ T-Cell Pathogenic Responses and Recognition of Type 1 Collagen in Rheumatic Heart Valve Disease.

    Passos LSA, Jha PK, Becker-Greene D, et al.

    Circulation 2022; (145(7)):531-548 doi:10.1161/CIRCULATIONAHA.121.057301.

    PMID: 35157519
  6. 6

    Chronic rheumatic heart disease with recrudescence of acute rheumatic fever on histology: a case report.

    Mutithu DW, Roberts R, Manganyi R, Ntusi NAB

    European heart journal. Case reports 2022; (6(7)):ytac278 doi:10.1093/ehjcr/ytac278.

    PMID: 35865226
  7. 7

    Chronic Mitral Valve Fibrosis in Rheumatic Heart Disease: From Immune Trigger to Inflammatory and Mechanical Progression.

    Liu Z, Liu R, Liang J, et al.

    Journal of the American Heart Association 2025; (14(22)):e045169 doi:10.1161/JAHA.125.045169.

    PMID: 41195785
  8. 8

    Histopathological Characterization of Mitral Valvular Lesions from Patients with Rheumatic Heart Disease.

    Gomes NFA, Pascoal-Xavier MA, Passos LSA, et al.

    Arquivos brasileiros de cardiologia 2021; (116(3)):404-412 doi:10.36660/abc.20200154.

    PMID: 33909767
  9. 9

    Degenerative mitral valve stenosis: Diagnosis and management.

    Al-Taweel A, Almahmoud MF, Khairandish Y, Ahmad M

    Echocardiography (Mount Kisco, N.Y.) 2019; (36(10)):1901-1909 doi:10.1111/echo.14495.

    PMID: 31587368
  10. 10

    Mitral Annular Calcification-Related Mitral Stenosis: 5-Year Outcomes and Prognostic Determinants in the JAMAC Study.

    Kato N, Watanabe T, Ishihara T, et al.

    Journal of the American College of Cardiology 2026; (87(23)):3260-3273 doi:10.1016/j.jacc.2025.12.004.

    PMID: 41778951
  11. 11

    Mechanisms of mitral annular calcification.

    Massera D, Kizer JR, Dweck MR

    Trends in cardiovascular medicine 2020; (30(5)):289-295 doi:10.1016/j.tcm.2019.07.011.

    PMID: 31402089
  12. 12

    Clinical challenges in calcific mitral stenosis from diagnosis to management.

    Kato N, Watanabe H, Pellikka PA, Guerrero M

    Journal of cardiology 2026; (87(1)):51-60 doi:10.1016/j.jjcc.2025.06.014.

    PMID: 40588211
  13. 13

    Mitral Annular Calcification and Calcific Mitral Stenosis: Role of Echocardiography in Hemodynamic Assessment and Management.

    Silbiger JJ

    Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 2021; (34(9)):923-931 doi:10.1016/j.echo.2021.04.007.

    PMID: 33857624
  14. 14

    A Novel Assessment Using Projected Transmitral Gradient Improves Diagnostic Yield of Doppler Hemodynamics in Rheumatic and Calcific Mitral Stenosis.

    Kato N, Pislaru SV, Padang R, et al.

    JACC. Cardiovascular imaging 2021; (14(3)):559-570 doi:10.1016/j.jcmg.2020.12.013.

    PMID: 33582068
  15. 15

    Outcomes of Severe Mitral Stenosis With the Revised Severity Criteria: Mitral Valve Replacement vs Percutaneous Mitral Valvuloplasty.

    Kim DY, Cho I, Kim K, et al.

    The Canadian journal of cardiology 2024; (40(1)):100-109 doi:10.1016/j.cjca.2023.09.006.

    PMID: 37716640
  16. 16

    Beyond the Valve Itself: Extra-valvular Phenotyping in Mitral Stenosis: A Novel Pathophysiology-driven Echocardiographic Staging System.

    Cordoni G, Mohty D, Shchendrygina A, et al.

    European cardiology 2026; (21()):e39 doi:10.15420/ecr.2026.05.

    PMID: 42488773
  17. 17

    Advances in Rheumatic Mitral Stenosis: Echocardiographic, Pathophysiologic, and Hemodynamic Considerations.

    Silbiger JJ

    Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 2021; (34(7)):709-722.e1 doi:10.1016/j.echo.2021.02.015.

    PMID: 33652082
  18. 18

    Managing asymptomatic severe rheumatic mitral stenosis in pregnancy: a case report.

    Eng-Frost J, Sinhal A, Ilton M, Wing-Lun E

    European heart journal. Case reports 2021; (5(3)):ytab010 doi:10.1093/ehjcr/ytab010.

    PMID: 33693306
  19. 19

    Echocardiography Assessment of Rheumatic Heart Disease: Implications for Percutaneous Balloon Mitral Valvuloplasty.

    Mohamed Ali A, Packer EJS, Omdal TR, et al.

    Current problems in cardiology 2023; (48(12)):102021 doi:10.1016/j.cpcardiol.2023.102021.

    PMID: 37544629
  20. 20

    Management of mitral stenosis: a systematic review of clinical practice guidelines and recommendations.

    Galusko V, Ionescu A, Edwards A, et al.

    European heart journal. Quality of care & clinical outcomes 2022; (8(6)):602-618 doi:10.1093/ehjqcco/qcab083.

    PMID: 34878131

This page explains how mitral valve stenosis develops and is measured for informational purposes only; it does not constitute medical advice. Your cardiology team should interpret your echocardiogram, symptoms, and treatment options.

Get notified when new evidence is published on mitral valve stenosis.

We monitor PubMed for new peer-reviewed studies on this topic and email a short summary when something meaningful changes.