What Is Aortic Stenosis?

An article written by Dr Edward Leatham, Consultant Cardiologist

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The aortic valve is the ‘non return’ valve positioned to prevent oxygenated blood pumped into the aorta from refluxing back into the heart after left ventricular contraction. When the aortic valve narrows, it restricts blood flow in a condition known as ‘aortic stenosis’.

Aortic stenosis (AS) is a progressive and potentially life-threatening condition. It predominantly affects older adults and has significant implications for cardiovascular health, life expectancy, and quality of life.  The incidence of AS is climbing because of increased life expectancy. Timely intervention, especially in symptomatic patients or those with progressing stenosis, is essential to optimise outcomes. This article explores the nuances of AS diagnosis, treatment decisions, and the importance of patient involvement in the care pathway.

Aortic stenosis is primarily caused by age-related calcification of the aortic valve, although other causes include congenital abnormalities (e.g., a bicuspid aortic valve) and rheumatic fever. Progressive calcification restricts valve mobility, impeding blood flow and increasing the workload on the heart. Over time, this can lead to left ventricular hypertrophy, heart failure, and even death if untreated.

Symptoms of Aortic Stenosis

AS has earned the moniker “Silent Killer” because patients often remain asymptomatic until the disease reaches an advanced stage. Many cases are picked up by a doctor or nurse detecting a heart murmur on listening to the heart sounds through a stethoscope, prompting a referral for an echocardiogram.

For some patients, especially those who rarely visit the doctor, symptoms can trigger testing and diagnosis.

Key symptoms associated with aortic stenosis include:

• Breathlessness (dyspnoea): Often triggered by exertion, indicating heart failure.
• Chest pain (angina): A result of increased oxygen demand by the thickened left ventricular wall.
• Fainting (syncope): Frequently occurring during exertion due to reduced cerebral blood flow.

These symptoms also play a critical role in determining the timing of intervention, as they reflect the functional impact of the disease rather than relying solely on echocardiographic measurements.

The Importance of Timely and Appropriate Intervention

Symptoms as the Key Indicator

In patients with aortic stenosis, symptoms are often the most reliable marker of disease severity and the need for intervention. While echocardiographic parameters such as transaortic velocity and mean pressure gradient are valuable, these measures do not always correlate perfectly with symptom burden:

• A patient with severe stenosis on imaging but no symptoms may not require immediate surgery.
• Conversely, a patient with moderate stenosis but significant symptoms may benefit from prompt intervention.

Diagnostic Challenges

For patients with ambiguous symptoms or borderline measurements, advanced diagnostic tools can clarify the clinical picture:

• Aortic calcium scoring via CT scans: Quantifies the degree of valve calcification, providing a more objective measure of disease severity.
• Transoesophageal echocardiography (TOE): Offers detailed imaging of valve leaflet mobility.
• Excluding other causes: Breathlessness can also result from conditions such as fibrotic lung disease, poorly controlled atrial fibrillation, or hypertension, all of which should be ruled out to avoid misdiagnosis.

Serial BNP (B-type natriuretic peptide) testing is a useful adjunct, as elevated and rising levels indicate increased strain on the heart, providing a valuable biomarker for disease progression.

Who Should Undergo Intervention?

Key considerations for intervention include:

1. Symptomatic Severe Aortic Stenosis: Symptoms such as angina, dyspnoea, or syncope are strong indications for valve replacement.
2. Progressive Stenosis in Fit Older Adults: For patients aged 75–85 with good life expectancy, early intervention can improve outcomes. Deciding between surgical aortic valve replacement (SAVR) and transcatheter aortic valve implantation (TAVI) should be individualised, considering surgical risk, anatomical factors, and patient preferences.

Surgical vs Transcatheter Approaches

The choice between SAVR and TAVI has evolved significantly:

• SAVR: Traditionally the treatment of choice for patients with low surgical risk and younger biological age, offering excellent long-term durability. However, it involves open-heart surgery with a longer recovery period.
• TAVI: A minimally invasive alternative, particularly suitable for older or higher-risk patients. While recovery is quicker, concerns about long-term durability and complications, such as paravalvular leak, persist.

For exceptionally fit older patients, SAVR may carry lower perioperative risk than expected and offer superior long-term outcomes. Early intervention in this group can mitigate risks associated with advancing disease while maintaining their quality of life.

Mortality and Survival Rates

The Historical Perspective

Historically, untreated aortic stenosis carried a grim prognosis. Dr Eugene Braunwald highlighted that symptomatic patients with severe AS had a 50% mortality rate within two years if untreated. This underscores the importance of timely recognition and intervention.

Modern Outcomes

Advancements in surgical techniques and valve technologies have significantly improved survival rates:

• Post-surgical survival rates: Approximately 89.7% survive at two years, 78.4% at five years, and 57.0% at ten years.
• Risk of sudden cardiac death in asymptomatic AS: Remains low at approximately 0.4% annually, underscoring the importance of focusing on symptoms rather than solely imaging findings.

These improvements have shifted the narrative from inevitable decline to proactive management with favourable outcomes.

Empowering Patients Through Shared Decision-making

The decision to intervene in aortic stenosis should involve a collaborative process, enabling patients to take an active role in their care. This approach builds trust and ensures alignment with the patient’s values and goals. Key elements of shared decision-making include:

1. Understanding Risks and Benefits: Providing clear, balanced information about the outcomes of SAVR versus TAVI.
2. Health Metrics as a Guide: Using objective data, such as BNP levels and imaging results, to inform timing and type of intervention.
3. The Consequences of Delayed Intervention: Helping patients appreciate the risks of disease progression, including heart failure, sudden cardiac death, and diminished quality of life.

The Role of Advanced Diagnostics and Therapies

The field of cardiology is rapidly evolving, with new tools offering better precision in the diagnosis and management of AS:

• Advanced Imaging: CT scans and TOE are providing more nuanced assessments of valve anatomy and calcification.
• Biomarkers: Serial BNP testing offers dynamic insights into disease progression and cardiac stress.
• Valve Technologies: Innovations in valve design continue to enhance durability and reduce complications, particularly in TAVI.

These advancements enable clinicians to offer tailored, patient-centred care that addresses the unique needs of each individual.

Conclusion

Aortic stenosis is a serious yet manageable condition. Modern advances in diagnosis and treatment have transformed its prognosis, allowing patients to live longer, healthier lives. The key lies in recognising symptoms early, leveraging advanced diagnostics to guide intervention timing, and involving patients in their treatment decisions.

For fit older adults, earlier intervention—often through SAVR—may reduce risks and enhance long-term quality of life. With a focus on patient-centred care, shared decision-making, and the integration of evolving technologies, the management of aortic stenosis continues to improve. Whether through SAVR or TAVI, the ultimate goal is to restore health and vitality, empowering patients to live fully and confidently in the years ahead.

Conclusion

Key messages

1. Aortic stenosis is an important and increasingly prevalent, preventable cause of heart failure in the elderly.
2. Decision making on the timing and type of aortic valve intervention involves a complex algorithm, best delivery by aortic valve specialist teams in centres equipped with advanced imaging facilities such as echo and CT, with access to the Heart Team based in tertiary cardiothoracic centres.

Other related articles

1. 1. 1. When to intervene in aortic stenosis

      2. Avoiding needless deaths in aortic stenosis 2018

      3. Aortic Stenosis: Then and Now 2018 Eugene Braunwald

      4. Aortic stenosis review article 2023
      5. Aortic Stenosis Overview Heart.org 2024

The Naked Heart is an educational project owned and operated by Dr Edward Leatham. It comprises a series of blog articles, videos and reels distributed on Tiktok, Youtube and Instagram  aimed to help educate both patients and healthcare professionals about cardiology related issues.

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