By Dr Nqobile Manzini — Cardiothoracic Surgeon
Why early recognition, structured surveillance and timely valve intervention can change the course of disease
Aortic stenosis may remain quiet for years. The murmur is often the first warning, long before the patient describes classical symptoms. That is why careful listening, correct investigation and timely referral matter.
A narrowed valve, but a much bigger story
Aortic stenosis is a narrowing of the opening through which blood leaves the left ventricle and enters the aorta. As the opening becomes smaller, the heart must generate progressively higher pressure to move blood forward. The left ventricle initially compensates by becoming thicker, but compensation has a limit. With time, the ventricle may become stiff, fibrotic and eventually fail.
This disease may be congenital or acquired. Congenital left ventricular outflow obstruction includes valvar stenosis, often associated with a bicuspid aortic valve, as well as subvalvar obstruction such as a subaortic membrane and supravalvar stenosis. A bicuspid valve has two leaflets instead of the usual three. Its abnormal mechanics create turbulent flow and repeated stress, so degeneration and calcification often appear earlier in adult life.
Acquired aortic stenosis is commonly caused by progressive calcific degeneration. This is the dominant pattern in higher-income countries and is seen increasingly as populations age. In low- and middle-income settings, rheumatic valve disease remains important. Rheumatic aortic stenosis is also less likely to be an isolated lesion; the patient may have associated aortic regurgitation or mitral valve disease.
The cause therefore influences the age at presentation, the other lesions that may be present and the way in which intervention should be planned.
How does the patient present?
The clinical relevance of a murmur depends on the underlying lesion and its severity. A child with congenital obstruction may be asymptomatic or may present early, depending on the degree and level of obstruction and whether other cardiac abnormalities are present.
Degenerative calcific disease usually presents later in life, often from the sixth or seventh decade onwards, although patients with a bicuspid valve may present earlier. Progression varies considerably between patients. Some remain clinically stable for years; others deteriorate more rapidly.
The symptoms that should make us pause are:
- Reduced effort tolerance or unusual fatigue
- Shortness of breath on exertion
- Chest pain or pressure
- Dizziness, presyncope or syncope
- Palpitations or a new arrhythmia
Symptoms or signs of heart failure
One of the difficulties is that patients do not always recognise their own decline. They may stop climbing stairs, walk more slowly or avoid activities that previously caused symptoms, and then describe themselves as “well”. A careful history must therefore ask not only whether symptoms are present, but whether the patient’s level of activity has changed.
The murmur is the beginning of the investigation
The classical finding is a harsh ejection systolic murmur, usually loudest at the right upper sternal border and radiating towards the carotid arteries. A slow-rising carotid pulse, a soft second heart sound or evidence of left ventricular hypertrophy may increase suspicion, but physical examination cannot determine severity on its own.
At primary-care level, the work-up should be directed and practical:
A 12-lead electrocardiogram may show left ventricular hypertrophy, conduction disease, ischaemic changes or an arrhythmia.
A chest radiograph may identify cardiac enlargement, valve or aortic calcification, and pulmonary congestion in advanced disease.
Baseline blood tests may include a full blood count, renal function and electrolytes. BNP or NT-proBNP can add prognostic information in selected patients.
Transthoracic echocardiography is the essential diagnostic test.
The echocardiogram establishes the valve anatomy and probable cause, quantifies the severity of stenosis, records the peak aortic jet velocity and mean gradient, estimates the valve area, assesses left ventricular size and systolic function, and identifies other valve lesions. Severe high-gradient aortic stenosis is generally defined by a mean gradient of at least 40 mmHg, a peak velocity of at least 4.0 m/s and an aortic valve area of 1.0 cm² or less. Discordant measurements require careful specialist review rather than interpretation of a single number in isolation.
Additional tests may include exercise testing to uncover symptoms in an apparently asymptomatic patient, CT calcium scoring when severity remains uncertain, coronary assessment before intervention and CT planning for a transcatheter procedure. Exercise testing in severe aortic stenosis should be performed in an appropriately supervised setting.
When should the patient be referred for valve intervention?
There is no medication that opens a severely stenosed valve. Medical therapy may treat associated hypertension, congestion, coronary disease or arrhythmia, but definitive treatment is valve replacement.
The 2025 ESC/EACTS guideline places the following patients firmly on the pathway to intervention:
Source: 2025 ESC/EACTS Guidelines for the management of valvular heart disease. Abbreviations: LVEF, left ventricular ejection fraction; Vmax, peak transvalvular velocity.
The guideline is equally clear that the choice between surgical aortic valve replacement (SAVR) and transcatheter aortic valve implantation (TAVI) must be made by a structured Heart Team. SAVR is recommended for patients younger than 70 years when surgical risk is low. TAVI is recommended for patients aged 70 years or older with stenosis of a tricuspid aortic valve when the anatomy is suitable. For the remaining patients, anatomy, surgical risk, frailty, comorbidity, life expectancy, valve durability and lifetime treatment strategy all matter.
SAVR is also recommended when severe aortic stenosis is present in a patient already undergoing coronary bypass surgery, surgery of the ascending aorta or surgery for another valve lesion.
Early intervention versus waiting: what does the literature show?
The central question is not whether symptomatic severe aortic stenosis should be treated; it should. The debate is how long it is safe to wait in a patient who says that they have no symptoms.
The final 10-year results of the RECOVERY trial, published in 2026, provide the longest randomised surgical evidence. The trial enrolled 145 low-risk patients with asymptomatic very severe aortic stenosis. Operative mortality or cardiovascular death occurred in 3% of patients assigned to early surgery and 24% assigned to conservative care. All-cause mortality was 15% versus 32%, and heart-failure hospitalisation occurred in 0% versus 19%, respectively. There was no operative mortality. These results apply particularly to low-risk patients with very severe disease and should not be generalised uncritically to every asymptomatic patient.
The AVATAR trial studied 157 low-risk patients with severe aortic stenosis, preserved ejection fraction and a negative exercise test, making them a genuinely asymptomatic group. After a median follow-up of 63 months, the composite of all-cause death, myocardial infarction, stroke or unplanned heart-failure hospitalisation occurred in 23.1% of the early-surgery group and 46.8% of the conservative-treatment group (hazard ratio 0.42).
Evidence from transcatheter treatment points in a similar direction for selected older patients. In the EARLY TAVR trial, 901 asymptomatic patients with severe aortic stenosis were assigned to early TAVI or clinical surveillance. At a median 3.8 years, death, stroke or unplanned cardiovascular hospitalisation occurred in 26.8% and 45.3%, respectively (hazard ratio 0.50). The difference was driven largely by fewer unplanned hospitalisations; mortality alone was not significantly different.
Not every study has shown a clear mortality benefit. In the EVOLVED trial, which selected 224 asymptomatic patients with severe aortic stenosis and myocardial fibrosis, the primary outcome of all-cause death or unplanned aortic stenosis-related hospitalisation occurred in 18% with early intervention and 23% with guideline-directed conservative care, a difference that was not statistically significant. Early intervention did, however, reduce unplanned aortic stenosis-related hospitalisation from 17% to 6% and reduced the likelihood of developing symptoms at 12 months.
Late referral may also carry a postoperative penalty. In a 2024 multicentre observational study of 2,030 patients operated on for high-gradient severe aortic stenosis, patients who were already symptomatic at surgery had an estimated 8.3-month loss in survival over the following 10 years compared with asymptomatic patients operated on with LVEF above 60%. An LVEF below 60% at intervention was associated with an estimated 11.4-month survival loss. As an observational analysis, this cannot prove causation, but it supports what we see clinically: replacing the valve may relieve the obstruction, yet it cannot always reverse advanced myocardial damage.
Taken together, the evidence does not mean that every asymptomatic patient should undergo immediate surgery. It means that passive waiting is no longer enough. Severity, exercise response, ventricular function, rate of progression, valve calcification, biomarkers, procedural risk and the reliability of follow-up must all be considered.
Active surveillance is an active plan
For a patient with severe aortic stenosis who is not yet undergoing intervention, surveillance must be deliberate. The 2025 ESC/EACTS guideline recommends follow-up at least every six months, ideally through a Heart Valve Centre, with education about symptom reporting and repeat echocardiographic assessment. Exercise testing can help when symptoms are uncertain, and serial natriuretic peptide measurements may add useful information.
The patient should know which changes require prompt review: new breathlessness, reduced effort tolerance, chest discomfort, dizziness, fainting, swelling or an unplanned reduction in daily activity. Once symptoms appear, referral should not be delayed.
The practical message
Aortic stenosis is a progressive mechanical obstruction. The murmur may be the first clue, but the timing of intervention is determined by the whole patient: symptoms, valve severity, ventricular response, associated disease and procedural risk.
As primary-care doctors and specialists, our task is not simply to wait for the classical triad of angina, syncope and heart failure. It is to recognise the patient whose heart is beginning to pay a price before that price becomes irreversible.
Listen carefully. Investigate the murmur. Refer early. Then let the Heart Team choose the right intervention at the right time.
References
Praz F, Borger MA, Lanz J, et al. 2025 ESC/EACTS Guidelines for the management of valvular heart disease. European Heart Journal. 2025;46(44):4635-4736. doi: 10.1093/eurheartj/ehaf194
Kang DH, et al. Early Surgery or Conservative Care for Asymptomatic Aortic Stenosis at 10 Years. New England Journal of Medicine. 2026. doi: 10.1056/NEJMoa2511920
Banovic M, Putnik S, Da Costa BR, et al. Aortic valve replacement vs conservative treatment in asymptomatic severe aortic stenosis: long-term follow-up of the AVATAR trial. European Heart Journal. 2024;45:4526-4535. doi: 10.1093/eurheartj/ehae585
Généreux P, Schwartz A, Oldemeyer JB, et al. Transcatheter Aortic-Valve Replacement for Asymptomatic Severe Aortic Stenosis. New England Journal of Medicine. 2025;392:217-227. doi: 10.1056/NEJMoa2405880
Loganath K, Craig NJ, Everett RJ, et al. Early Intervention in Patients With Asymptomatic Severe Aortic Stenosis and Myocardial Fibrosis: The EVOLVED Randomized Clinical Trial. JAMA. 2025;333(3):213-221. doi: 10.1001/jama.2024.22730
De Azevedo D, Boute M, Tribouilloy C, et al. Quantifying the Survival Loss Linked to Late Therapeutic Indication in High-Gradient Severe Aortic Stenosis. JACC: Advances. 2024;3(3):100830. doi: 10.1016/j.jacadv.2024.100830
This article is intended for professional education. Management decisions should be individualised through a multidisciplinary Heart Team and aligned with current local guidance and available resources.
Clinical situation | ESC/EACTS 2025 recommendation | Class
Symptomatic severe high-gradient aortic stenosis: mean gradient ≥40 mmHg, Vmax ≥4.0 m/s and valve area ≤1.0 cm² | Valve intervention is recommended. | I B
Symptomatic low-flow, low-gradient severe stenosis with LVEF <50% | Intervention is recommended after confirming that the stenosis is truly severe. | I B
Symptomatic low-flow, low-gradient severe stenosis with LVEF ≥50% | Intervention should be considered after careful confirmation of severity. | IIa B
Asymptomatic severe aortic stenosis with LVEF <50% and no other explanation | Intervention is recommended. | I B
Genuinely asymptomatic severe high-gradient stenosis with LVEF ≥50% and low procedural risk | Early intervention should be considered as an alternative to close active surveillance. | IIa A
Asymptomatic severe stenosis with low procedural risk and a high-risk marker | Intervention should be considered. High-risk markers include very severe stenosis (mean gradient ≥60 mmHg or Vmax >5.0 m/s), severe calcification with Vmax progression ≥0.3 m/s/year, repeatedly elevated BNP/NT-proBNP >3 times the age- and sex-corrected normal range, or LVEF <55% without another cause. | IIa B
Asymptomatic severe stenosis with a sustained fall in blood pressure >20 mmHg during exercise testing | Intervention should be considered. | IIa C