About This Page
This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Most common valve lesion requiring surgery in the UK — degenerative calcific disease in elderly, bicuspid valve in younger patients
- Classic triad of symptoms: exertional angina, syncope, and heart failure (dyspnoea) — once symptomatic, prognosis is poor without intervention
- Ejection systolic crescendo-decrescendo murmur at aortic area, radiating to carotids; slow-rising pulse, narrow pulse pressure
- Diagnosis and severity grading by echocardiography: severe = AVA <1 cm², mean gradient >40 mmHg, Vmax >4 m/s
- Definitive treatment: surgical AVR (SAVR) or transcatheter AVR (TAVI) per NICE NG208; no medical therapy reverses the stenosis
Overview
Aortic stenosis (AS) is the progressive narrowing of the aortic valve orifice, obstructing left ventricular outflow. The commonest cause in the UK and developed world is age-related degenerative calcification of a previously normal trileaflet valve (typically presents >65 years). Bicuspid aortic valve (present in 1–2% of the population) is the leading cause in younger patients (presenting at 40–60 years). Rheumatic heart disease remains an important cause globally but is rare in the UK. The left ventricle hypertrophies concentrically to maintain cardiac output, but eventually decompensates leading to heart failure.
Epidemiology
Aortic stenosis is the most prevalent valvular heart disease in the Western world. Prevalence of severe AS is approximately 3–5% in those over 75 years. Risk factors for degenerative AS mirror those for atherosclerosis: hypertension, hyperlipidaemia, smoking, diabetes. Bicuspid aortic valve has a male predominance (3:1). Once symptoms develop, median survival without intervention is 2–3 years for angina, 3 years for syncope, and 1–2 years for heart failure.
Clinical Features
Symptoms
Exertional dyspnoea (commonest initial symptom)
Angina on exertion (increased myocardial O₂ demand with reduced supply)
Exertional syncope or presyncope (fixed cardiac output unable to meet demand)
Fatigue and reduced exercise tolerance
Symptoms of heart failure (orthopnoea, PND) — late presentation
Sudden cardiac death (rare first presentation, usually in severe symptomatic AS)
Signs
Ejection systolic crescendo-decrescendo murmur loudest at right upper sternal edge (aortic area), radiating to carotids
Slow-rising pulse (pulsus tardus) with low volume (pulsus parvus)
Narrow pulse pressure
Soft or absent S2 (calcified, immobile valve cusps)
S4 (reduced LV compliance from hypertrophy)
Heaving, sustained (but non-displaced) apex beat (pressure-loaded LV)
Late peaking murmur indicates more severe stenosis
Investigations
First-line
Echocardiography (TTE)Gold standard. Assess valve morphology, AVA, peak velocity (Vmax), mean gradient, LVEF. Severe: AVA <1 cm², mean gradient >40 mmHg, Vmax >4 m/s
ECGLVH (tall R waves in V5–V6, deep S in V1–V2), strain pattern (ST depression, T inversion in lateral leads)
Second-line
Chest X-rayMay show calcified aortic valve, post-stenotic dilatation of ascending aorta, LVH silhouette. Normal CXR does not exclude severe AS
Exercise stress testingCan unmask symptoms in apparently asymptomatic severe AS — perform ONLY under supervised conditions
BNP/NT-proBNPElevated levels in asymptomatic AS predict adverse outcomes and may support referral for intervention
Specialist
Cardiac CT (calcium scoring)Quantify aortic valve calcification if echo-grading discordant (especially low-flow low-gradient AS)
Dobutamine stress echoDifferentiate true severe AS from pseudo-severe AS in patients with low LVEF and low gradient
Cardiac catheterisationInvasive gradient measurement if non-invasive tests inconclusive; coronary assessment pre-surgery
1
Surveillance (asymptomatic mild-moderate AS)
- Echo surveillance: mild AS every 3–5 years, moderate every 1–2 years, severe annually
- Advise patients to report new symptoms promptly
- No proven medical therapy to slow progression — manage cardiovascular risk factors
2
Symptomatic severe AS — definitive intervention
- Surgical aortic valve replacement (SAVR) — gold standard for patients at low/intermediate surgical risk
- Transcatheter aortic valve implantation (TAVI) — for patients at high surgical risk or where surgery is unsuitable
- Balloon aortic valvuloplasty — temporary bridge in haemodynamically unstable patients or as bridge to definitive procedure
3
Asymptomatic severe AS — consider referral if
- Vmax >5 m/s, AVA <0.6 cm², LVEF <55%, BNP >2× upper limit of normal
- Abnormal exercise test (symptoms, BP drop, arrhythmia)
- Rapid progression on serial echo
4
General measures
- Avoid strenuous exercise if severe AS
- Caution with vasodilators and diuretics — may precipitate hypotension in fixed obstruction
- Endocarditis awareness — educate patient, maintain dental hygiene
Complications
- Heart failure: LV decompensation — the most common cause of death in unoperated severe AS
- Sudden cardiac death: Arrhythmias (VT/VF) in severe AS, especially during exertion
- Infective endocarditis: Abnormal valve predisposes to IE
- Systemic embolisation: Calcific emboli from the valve (rare)
- GI bleeding: Heyde syndrome — acquired von Willebrand disease with angiodysplasia-related GI bleeding
- Atrial fibrillation: Loss of atrial contraction is poorly tolerated in AS (dependent on atrial kick)
UKMLA Exam Tips
- 1The classic triad: angina, syncope, dyspnoea (SAD) — once symptoms develop, prognosis is grim without intervention
- 2Ejection systolic murmur radiating to carotids + slow-rising pulse + narrow pulse pressure = AS until proven otherwise
- 3Soft/absent S2 = severe AS (calcified immobile cusps cannot produce a normal closing sound)
- 4DO NOT confuse with HOCM — AS murmur increases with increased afterload (standing → reduces HOCM murmur but does not reduce AS murmur significantly). HOCM murmur increases on Valsalva/standing
- 5Heyde syndrome is a favourite obscure exam question — severe AS + GI bleeding from angiodysplasia
- 6TAVI is increasingly used but NICE currently limits it to high surgical risk patients
- 7Avoid vigorous exercise in severe AS — risk of sudden death
practicetest your knowledge on aortic stenosisApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — cardiovascular and beyond.
open q-bank