Aortic Stenosis

Meet the patient

A 74-year-old man is sent to the cardiology clinic by his GP, who heard a murmur. He insists he feels well, then admits, almost as an afterthought, that he stopped walking his dog six months ago because his legs "give out" on the hill, and that last month he "felt faint" carrying the shopping in from the car.^[1]

His carotid pulse rises slowly under your finger like a hill rather than a tap. The apex is heaving and not displaced. At the right second intercostal space there is a harsh crescendo-decrescendo murmur radiating into the neck, the second heart sound is single, and there is a soft fourth sound at the apex.^[1]

Two exam questions are now live, and the same answer closes both: is this severe, and is it symptomatic? Because once severe AS declares itself, the only thing that changes survival is the operating list — not a drug, not a statin, not "watch and wait". Everything below is built to answer those two questions at consultant depth.^[1][2]

What aortic stenosis is — and the three levels of outflow obstruction

It is a fixed, mechanical obstruction to LV outflow at the valve, produced by thickening, fibrosis and calcification of the cusps. The left ventricle pumps against a narrowed exit, generating a pressure gradient that rises as the orifice shrinks.^[1]

The LV outflow tract can be obstructed at three anatomical levels, and an examiner will test whether you know the difference. Valvular is the valve itself (this topic). Subvalvular is a discrete membrane, a tunnel, or hypertrophic cardiomyopathy. Supravalvular sits above the sinuses — Williams-Beuren syndrome, elfin facies, hypercalcaemia. Only valvular AS is detailed here; the others live in the differential.^[1]

It is not "wear and tear". Calcific AS is an active process with similarities to atherosclerosis: leaflet lipid infiltration and inflammation followed by fibrosis and calcification. That is why the statin hypothesis was reasonable, and why its failure (below) is worth a viva sentence.^[9][15]

The skill is not naming the murmur. It is recognising severe disease from the bedside, stratifying symptom risk, defining severity on echo (especially the low-flow variants), and referring at the correct threshold — because AVR is the only survival-modifying intervention, and the window closes once the LV decompensates.^[1][2]

Classification — by aetiology and by haemodynamics

AS is classified two ways: by what caused it (which predicts the age and the patient), and by how severe it is (which drives every management decision). Both must be answerable in a viva.^[1]

Aetiology — read the age, read the valve

^[1]

Haemodynamic severity — the "4-40-1" rule

Severity is graded by peak jet velocity (Vmax), mean gradient and aortic valve area (AVA, by the continuity equation). For small patients use the indexed AVA.^[1][2]

^{[1] [20]}

The number rule for severe AS is 4-40-1: velocity 4 m/s, gradient 40 mmHg, area 1.0 cm2. High-gradient severe AS is defined by Vmax at least 4 m/s or mean gradient at least 40 mmHg; the valve area is typically 1.0 cm2 or less (indexed 0.6 cm2/m2 or less) but is not itself required to call the stenosis severe — a small area with a low gradient is the low-flow problem below. Say the trio in one breath in a viva and you have the grading marks.^[1][2]

The indexed AVA earns its place in small patients (body surface area under 1.7 m2), where an absolute AVA under 1.0 cm2 with a Vmax under 4 m/s and a mean gradient under 40 mmHg may be re-classified as moderate and an unnecessary operation avoided. It should be avoided in overweight patients, in whom it overestimates severity, and patients who are "severe" by indexed area alone do better than those with a genuinely small absolute area.^[20] Very severe AS carries a high event rate and is an interventional trigger — Class 2a in the 2020 ACC/AHA at Vmax at least 5.0 m/s, and Class 2a in the 2021 ESC/EACTS for a mean gradient at least 60 mmHg or Vmax over 5 m/s (with LVEF over 55 percent, a normal exercise test and low procedural risk).^[1][2]

Low-flow low-gradient AS — the variant the standard thresholds miss

A separate classification is essential because the 4-40-1 thresholds misclassify it. Two subtypes:^[2]

• Classical low-flow low-gradient — LVEF under 50 percent and/or stroke volume index under 35 mL/m2, AVA under 1.0 cm2, mean gradient under 40 mmHg. Low-dose dobutamine stress echo separates truly severe from pseudo-severe; no contractile reserve means a high mortality on conservative therapy.^[14][13]
• Paradoxical low-flow low-gradient — LVEF at least 50 percent but stroke volume index under 35 mL/m2 (pronounced concentric remodelling with a small LV cavity), AVA under 1.0 cm2, mean gradient under 40 mmHg. Confirmed by CT aortic calcium score.^[12][11]

How common, how deadly — the numbers you own

^{[1] [15] [19] [20]}

AS is the commonest valve lesion requiring surgical or percutaneous intervention, with a prevalence of up to 5 percent in people over 75.^[20] US data put AS at 1 to 2 percent of adults over 65 and about 12 percent of adults over 75, and worldwide it causes more than 100,000 deaths a year.^[15] As life expectancy rises, the burden of AS — and of transcatheter AVR — keeps growing.^[2]

Risk factors for calcific AS overlap closely with atherosclerosis — age, male sex, hypertension, hyperlipidaemia, smoking, diabetes, metabolic syndrome and chronic kidney disease. These are the same patients who have systemic atherosclerosis, because AS is an active process with similarities to atherosclerosis.^[9][8]

Why every symptom happens — pressure overload and the hypertrophied ventricle

AS is mechanical obstruction sitting on top of an active biological process, with haemodynamic and cellular consequences that explain every symptom.^[1]

Concentric hypertrophy — the compensation that buys years

Narrowing the orifice raises the pressure gradient between LV and aorta. To push a normal stroke volume across a stenotic valve the LV must generate higher systolic pressure — chronic pressure overload. The LV compensates with concentric hypertrophy (new sarcomeres added in parallel), thickening the wall to normalise wall stress per Laplace (wall stress = pressure times radius over twice wall thickness). This preserves ejection fraction for years — the patient is asymptomatic even with a tiny AVA.^[1]

Enlarge

Why angina with normal coronaries

Angina occurs in AS even when the coronary arteries are angiographically normal — 13 of 14 such patients in the classical coronary-reserve study had angina. Three mechanisms converge:^[21][1]

1. Increased demand — the hypertrophied LV has more muscle to perfuse and generates higher systolic pressures.
2. Decreased supply — the thick wall compresses intramural vessels in systole, and the low diastolic perfusion gradient (raised LVEDP, low post-stenotic aortic diastolic pressure) starves the subendocardium.
3. Reduced coronary flow reserve — coronary reserve to the hypertrophied left ventricle is selectively and markedly reduced (peak-to-resting coronary flow velocity ratio down by more than half) even with normal coronary arteries. The result is demand ischaemia and subendocardial ischaemia, the substrate for angina, exertional dyspnoea and ventricular arrhythmia.^[21]

Why syncope

Exertion causes peripheral vasodilatation; in AS the LV cannot raise cardiac output across the fixed obstruction, so systemic arterial pressure and cerebral perfusion fall and the patient feels pre-syncopal or faints. Syncope may also be arrhythmic — ventricular tachycardia or fibrillation from ischaemic, hypertrophied muscle, or conduction disease as calcium eats into the septum and His-Purkinje tissue.^[1]

The slide into heart failure

Three stages follow one another as AVA narrows:^[1]

1. Compensated — concentric hypertrophy, normal EF, often asymptomatic.
2. Diastolic dysfunction — the hypertrophied LV is stiff, LVEDP rises, the atrial kick (the S4) becomes critical; exertional dyspnoea, orthopnoea and pulmonary congestion appear.
3. Systolic dysfunction — once afterload mismatch and interstitial fibrosis overwhelm the hypertrophic response, EF falls and the heart dilates; the murmur softens as forward output drops. This is the late, decompensated, worst-prognosis phase.^[1]

The osteogenic biology — why statins failed

Calcific AS is not passive wear: the leaflets undergo lipid infiltration and inflammation, followed by fibrosis and calcification — an active, self-perpetuating process rather than simple mechanical erosion. This is what makes it biologically atherosclerosis-like, and it is why a lipid-lowering strategy looked plausible.^[15][9]

Clinical presentation — the triad, the pulse, the murmur

Most patients with mild-to-moderate AS are asymptomatic, found on a murmur or an incidental echo. Symptoms indicate severe disease and a sharply reduced survival until AVR.^[1]

The severe-AS triad — "ASH", with a survival clock on each

^[1]

Other common symptoms are exertional dyspnoea (the commonest early symptom), orthopnoea and paroxysmal nocturnal dyspnoea as the LV decompensates, fatigue and effort intolerance from low forward output, and palpitations from atrial fibrillation. Sudden cardiac death in asymptomatic severe AS is uncommon — under 1 percent per year when patients are followed prospectively and report symptoms promptly — which is precisely why surveillance and patient education matter.^[1]

The bedside signs that earn marks

• Pulse — slow-rising and small volume = pulsus parvus et tardus, best felt at the carotid; in critical AS the pulse is nearly imperceptible (threshold). A carotid thrill (shudder) may accompany it.
• Apex — sustained, heaving, non-displaced (concentric LVH); displaced only late, when systolic dysfunction supervenes.
• Auscultation (right 2nd ICS):
  • Ejection systolic murmur — crescendo-decrescendo, harsh, radiating to the carotids, and in older patients also audible at the apex — the Gallavardin phenomenon.^[24] Intensity tracks severity only early; a soft murmur in late disease is ominous.
  • Ejection click — high-pitched, just after S1, means a mobile, often bicuspid valve; disappears once the valve calcifies.
  • A2 soft or absent — the calcified immobile valve cannot snap shut; S2 becomes single or shows paradoxical (reversed) splitting (delayed A2 falls behind P2 from prolonged LV ejection).
  • S4 gallop — a stiff, hypertrophied LV receiving its atrial kick (needs sinus rhythm).
• Other — a basal ejection thrill at the right 2nd ICS means critical stenosis. Right-heart failure signs (raised JVP, hepatomegaly, oedema) appear late.^[1]

Atypical presentations examiners test for

• Elderly or frail — may present in pulmonary oedema or cardiogenic shock with only a soft or inaudible murmur (low-output state): the "low-gradient", critical AS presentation.
• Atrial fibrillation — precipitates decompensation by stealing the atrial kick.
• Heyde syndrome — the triad of severe AS, gastrointestinal bleeding from angiodysplasia, and acquired von Willebrand syndrome type 2A: the high shear stress of the stenotic valve destroys the large vWF multimers, and correcting the valve (SAVR or TAVI) restores them and usually settles the bleeding.^[22]
• Endocarditis — fever, emboli, new murmur; bicuspid valves carry higher risk.^[1]

The differential — one ejection murmur, seven answers

The bedside question is "is this ejection systolic murmur AS, or something else?" The pulse, the radiation, and the response to dynamic manoeuvres settle most cases.^[1]

^[1]

Differentiating AS from HOCM at the bedside is the favourite viva question. They are opposite on Valsalva and squatting: the HOCM murmur gets louder where the AS murmur gets softer. The HOCM pulse is jerky or bifid, not slow-rising, and the HOCM murmur does not radiate to the carotids.^[1]

Dynamic auscultation — the table every candidate must own

The examiner wants the dynamic auscultation reproduced and explained, not just stated.^[1]

^[1]

The discriminator line: squatting and Valsalva move AS and HOCM in opposite directions. The pulse in AS is slow-rising (parvus et tardus); in HOCM it is jerky or bisferiens.^[1]

Carotid assessment — use the pads, not the thumb

Palpate the carotid with the pads of the fingers, never the thumb (you will feel your own pulse). In severe AS the upstroke is delayed, weak and sustained — parvus et tardus. A palpable carotid thrill (shudder) supports critical stenosis. Compare the arms: in supravalvular AS the right arm pressure exceeds the left (reported differences of the order of 25 mmHg), because the Coanda effect directs the high-velocity jet preferentially into the innominate artery.^[23]

Ejection click and S2 — what their absence tells you

• Ejection click — high-pitched, just after S1, at the apex or left sternal edge. Means a mobile, often bicuspid valve. It disappears as the valve calcifies, so its absence in calcific AS is expected; its presence should send you hunting for bicuspid morphology.
• S2 — in severe AS, A2 is soft or absent (the valve cannot move). If LV ejection is markedly prolonged, A2 is delayed and falls after P2, producing paradoxical (reversed) splitting — best at the left 2nd or 3rd ICS, the two components moving further apart in expiration.
• S4 — low-pitched presystolic sound at the apex, a stiff hypertrophied LV receiving its atrial kick. Needs sinus rhythm.^[1]

Investigations — echo is the test; everything else is context

Echocardiography — the definitive test

Transthoracic echocardiography (TTE) is first-line and usually sufficient. It defines:^[1][2]

• Valve morphology — bicuspid versus tri-leaflet versus rheumatic; degree and distribution of calcification.
• Peak aortic jet velocity (Vmax) — by continuous-wave Doppler, aligned to the jet.
• Mean and peak transvalvular gradients.
• Aortic valve area (AVA) by the continuity equation: AVA equals the LVOT cross-sectional area times the LVOT velocity-time integral, divided by the aortic jet velocity-time integral. The continuity equation appears in nearly every AS viva.
• LV function — EF, wall thickness, mass, diastolic function; stroke volume and stroke-volume index (essential for low-flow low-gradient AS).
• Associated lesions — aortic regurgitation, mitral disease; aortic root and ascending aorta dimensions (especially in BAV).^[1]

Dobutamine stress echo — for low-flow low-gradient AS

When the AVA is small but the gradient is low (under 40 mmHg) and EF is reduced, the question is whether the valve is truly severe or only pseudo-severe (low flow making a moderate valve look tight). Dobutamine stress echo raises contractility and flow:^[2]

• Truly severe AS — gradient rises with flow to at least 40 mmHg, AVA stays under 1.0 cm2.
• Pseudo-severe AS — AVA enlarges with flow to over 1.0 cm2; the valve was never critical.
• No contractile reserve (stroke volume rise under 20 percent) carries a poor prognosis and high peri-procedural risk.^[2]

CT aortic valve calcium scoring is the alternative confirmation, especially in paradoxical low-flow low-gradient AS with normal EF. The 2021 ESC/EACTS Agatston thresholds make severe AS highly likely above 3000 AU in men and 1600 AU in women (likely above 2000 and 1200; unlikely below 1600 and 800); the 2020 ACC/AHA quotes 2000 AU in men and 1300 AU in women.^[2][1]

ECG and chest X-ray

ECG shows LV hypertrophy by voltage criteria (Sokolow-Lyon: SV1 plus RV5 or RV6 over 35 mm; Cornell: RaVL plus SV3 over 28 mm in men and over 20 mm in women)^[25] with a strain pattern (lateral ST depression and T-wave inversion), left atrial abnormality (a broad P wave of at least 0.12 s in lead II with a negative terminal P force in V1)^[26], and conduction abnormalities — first-degree AV block, LBBB, AF.^[1]

Chest X-ray is often normal early. Look for cardiomegaly, pulmonary venous congestion or oedema, calcification of the aortic valve (best on a lateral or heavily penetrated film), post-stenotic dilatation of the ascending aorta, and (in BAV) an enlarged aortic knuckle.^[1]

CT and invasive coronary angiography — pre-operative road maps

Pre-operative coronary angiography is recommended before valve surgery in men over 40 and postmenopausal women, and in anyone with known cardiovascular disease, suspected myocardial ischaemia or LV systolic dysfunction, because concomitant CABG at SAVR deals with significant CAD. ECG-gated cardiac CT is essential before TAVI — for annular sizing (which sets prosthesis size and the risk of paravalvular leak or annular injury), iliofemoral access assessment, and calcium burden and annular calcium distribution (predicts conduction injury and paravalvular leak).^[2]

Exercise testing — and when it is forbidden

Exercise testing is contraindicated in symptomatic severe AS — Class 3 (Harm), because of the risk of severe haemodynamic compromise: syncope, ventricular tachycardia, death. It is reasonable (Class 2a) in asymptomatic severe AS — to unmask symptoms, reduced exercise tolerance, or an abnormal blood-pressure response (a fall in systolic BP of at least 10 mmHg from baseline to peak exercise in the 2020 ACC/AHA; a sustained fall of more than 20 mmHg in the 2021 ESC/EACTS) that re-classifies the patient as AVR-indicated.^[1][2]

Biomarkers — the "asymptomatic" patient who is hiding symptoms

BNP or NT-proBNP is increasingly used in apparently asymptomatic severe AS: a level more than three times the age- and sex-corrected normal range, confirmed on repeat measurement and with no other explanation, is a Class 2a trigger for intervention in low-risk patients in both the 2020 ACC/AHA and the 2021 ESC/EACTS — the reasoning being that "asymptomatic" patients with a high BNP are often exercising less and hiding their symptoms.^[1][2]

Acute decompensation — the three drugs that collapse the ventricle

A patient with severe AS who presents in acute pulmonary oedema or cardiogenic shock is a high-risk emergency. The fixed outflow obstruction means the LV is exquisitely preload- and afterload-sensitive.^[1]

Immediate measures (ABCDE):^[1]

• Sit upright with oxygen. CPAP or NIV relieves breathlessness and metabolic disturbance faster than oxygen alone in acute cardiogenic pulmonary oedema.^[10]
• Cautious IV loop diuretic — lower than usual doses; over-diuresis empties the stiff, hypertrophied LV and forward output falls.
• IV access, monitoring, bloods (troponin, BNP, lactate, cultures if sepsis is suspected).
• Treat precipitants: AF (rate-control cautiously; cardiovert if unstable), ischaemia, anaemia, infection, arrhythmia.^[1]

AVOID — these are the classic traps:^[1]

• Vasodilators — nitrates, ACE-inhibitors, hydralazine: they drop afterload, collapse LV output, and cause profound hypotension.
• Aggressive diuresis — empties the stiff LV, drops preload, drops output.
• Negative inotropes — beta-blockers and the non-dihydropyridine calcium-channel blockers (verapamil, diltiazem) depress the compensation that is keeping the LV ejecting.^[1]

Refractory or cardiogenic shock:^[1]

• Cautious inotrope — low-dose dobutamine to augment contractility and forward output (and it may raise the gradient).
• Mechanical support — an intra-aortic balloon pump if necessary (used with caution — it raises the afterload the LV must pump against); VA-ECMO in extremis as a bridge.
• Balloon aortic valvuloplasty (BAV) — percutaneous balloon inflation splits fused commissures and acutely lowers the gradient; a bridge to definitive AVR or TAVI in the critically ill, or palliation in those not fit for AVR. It is not definitive — restenosis occurs within about 6 months.^[1][2]

Definitive AVR should be planned during the index admission once the patient is stabilised — survival without it is poor.^[1]

Definitive management — AVR is the only thing that changes survival

Enlarge

Aortic valve replacement is the only therapy proven to improve survival in severe AS. No drug halts or reverses the valve process. Two routes — surgical AVR (SAVR) and transcatheter AVR (TAVI, also written TAVR) — are now available across the entire risk spectrum.^[1][2]

Class I indications for AVR (2020 ACC/AHA)

AVR is indicated in any of:^[1]

1. Symptomatic severe AS (any of the triad — angina, syncope, heart failure — or a symptomatic exertional BP drop).
2. Asymptomatic severe AS with LVEF under 50 percent.
3. Severe AS when other cardiac surgery is planned (CABG, mitral surgery, ascending aorta repair).

Class 2a indications in asymptomatic severe AS (low surgical risk)

• Rapid progression — a rise in Vmax of at least 0.3 m/s per year in high-gradient severe AS.
• Very severe AS — Vmax at least 5.0 m/s (2020 ACC/AHA); mean gradient at least 60 mmHg or Vmax over 5 m/s with LVEF over 55 percent and a normal exercise test (2021 ESC/EACTS).
• Abnormal exercise test — symptoms, reduced exercise tolerance, or a fall in systolic BP of at least 10 mmHg from baseline to peak exercise (a sustained fall over 20 mmHg in the ESC).
• Markedly raised BNP — more than three times the age- and sex-corrected normal range, confirmed on repeat, with no other cause.^[1][2]

SAVR versus TAVI — a heart-team decision by age, risk and anatomy

The 2020 ACC/AHA guideline uses age cut-points:^[1]

^[1]

The 2021 ESC/EACTS guideline uses a single cut-point: SAVR in patients under 75 at low surgical risk (STS-PROM or EuroSCORE II under 4 percent); TAVI in patients 75 or over, at high surgical risk, or unsuitable for surgery — with the heart team arbitrating everyone else.^[2]

SAVR is favoured when the patient is young; the anatomy is bicuspid with an unfavourable TAVI landing zone; concomitant cardiac surgery is needed (CABG, mitral repair, ascending aorta replacement); the vascular access is unfavourable (tortuous, calcified iliofemoral); annular or LVOT calcium raises the TAVI risk of rupture or paravalvular leak; there is infective endocarditis; or the indication is one of the Class 2a asymptomatic triggers (abnormal exercise test, very severe AS, rapid progression, raised BNP), for which the guideline recommends SAVR in preference to TAVI.^[1]

TAVI is favoured when the patient is elderly or frail; the surgical risk is high or prohibitive (STS-PROM or EuroSCORE II); the chest is hostile (previous thoracotomy, radiation); there is a porcelain aorta; the iliofemoral access and annular anatomy are favourable; or the patient is a poor candidate for extracorporeal circulation.^[1]

Prosthetic choice for SAVR (mechanical versus bioprosthetic): a mechanical prosthesis is reasonable under 50 years; a bioprosthesis is reasonable over 65, and either is acceptable between 50 and 65; a bioprosthesis is recommended at any age when vitamin-K-antagonist anticoagulation is contraindicated, cannot be managed properly or is not wanted. The PARTNER, SURTAVI and Evolut trials established TAVI non-inferiority across risk strata.^{[1][3][4][5][6][7][16]}

Medical therapy — supportive only

• No drug halts calcific AS. The SEAS trial (ezetimibe plus simvastatin, NEJM 2008) and the ASTRONOMER trial (rosuvastatin, Circulation 2010) both failed to show any reduction in progression or clinical events, despite the atherosclerosis-like biology.^[8][9]
• Treat comorbidities carefully: hypertension (ACE-inhibitor cautiously, low dose, watching for hypotension); heart failure (diuretics; avoid over-diuresis); atrial fibrillation (restore or control the rate promptly — losing the atrial kick can precipitate pulmonary oedema).
• Endocarditis prophylaxis is no longer routine for unrepaired native valves, but is reasonable in high-risk subsets (previous endocarditis, prosthetic valve) before dental procedures.^[1]

Balloon aortic valvuloplasty — a bridge, never a destination

Not definitive. Restenosis in about 6 months; used as a bridge to AVR in the critically ill, in pregnancy, or as palliation in patients not fit for AVR. In young patients with non-calcified bicuspid AS it may have a role, but AVR remains definitive.^[1]

Special situations you will actually meet

Low-flow low-gradient AS — confirm before you refer

Two subtypes, both frequently missed by the standard thresholds:^[2]

^[1]

Confirming true severity is the whole point. A small AVA with a low gradient could be pseudo-severe (a moderate valve made to look tight by low flow) or truly severe. Dobutamine stress echo and CT calcium score distinguish them and decide who is referred for AVR.^[1]

Bicuspid aortic valve — address the valve, never forget the aorta

BAV affects 1 to 2 percent of the population and is the commonest congenital cardiac lesion. The valve has two cusps (with a raphe marking the fused commissure), predisposes to early AS and/or AR, and carries an aortopathy of the ascending aorta and root (risk of dilatation, dissection, rupture). Coarctation of the aorta co-exists in a subset — so every BAV patient needs Doppler of the descending and abdominal aorta (or arm-versus-leg blood pressures), and every coarctation patient needs a BAV screen. Surveillance of the aortic sinuses and ascending aorta is mandatory: lifelong serial imaging once the diameter reaches 4.0 cm, with CT or MRI when echo is inadequate, and at least annual imaging once it exceeds 4.5 cm; surgical replacement above 5.5 cm (5.0 to 5.5 cm when there is a risk factor for dissection — family history of dissection, growth over 0.5 cm per year, or coarctation), and concomitant aortic replacement at SAVR once the diameter is 4.5 cm or more.^[1]

Rheumatic AS — bring the mitral valve into the answer

Defined by commissural fusion (especially the medial commissures producing a fish-mouth orifice), almost always with co-existing mitral disease. Predominant in young patients in India and other rheumatic-fever-endemic regions. The ejection click is usually absent (calcified) and the murmur may be softer. Management is the same — AVR when severe and symptomatic — often combined with mitral surgery.^[1]

Asymptomatic severe AS — safe now, not safe forever

Most are safe in the short term — survival through the asymptomatic phase matches age-matched controls and sudden death runs under 1 percent per year — but risk climbs steeply with Vmax: in very severe AS the rate of symptom onset is about 50 percent at 2 years^[1], and in the prospective very-severe cohort (Vmax at least 5.0 m/s) event-free survival was 64 percent at 1 year, 36 percent at 2 years and 25 percent at 3 years, with peak velocity — not valve area — the independent predictor.^[18] Surveillance TTE every 6 to 12 months for severe AS, 1 to 2 years for moderate and 3 to 5 years for mild.^[1][15] Patient education is critical: report any new symptom — especially exertional dyspnoea, chest pain or pre-syncope — immediately, because symptoms re-classify the patient as AVR-indicated.^[1]

Pregnancy and special populations

Pregnancy imposes a large rise in blood volume and cardiac output and a fall in afterload — poorly tolerated by a fixed LV outflow obstruction. Asymptomatic mild-to-moderate AS usually tolerates pregnancy with careful monitoring. Symptomatic severe AS carries a significant risk of pulmonary oedema, syncope and maternal death.^[1][2]

• Pre-conception counselling is ideal: AVR before pregnancy if severe AS, or BAV as a bridge in symptomatic severe AS to permit pregnancy.
• During pregnancy: avoid volume depletion (epidural preferred over general anaesthesia for delivery; avoid supine hypotension; left lateral position), beta-blockade cautiously for rate, monitor in a joint obstetric-cardiology clinic, deliver in a cardiac centre.
• Severe symptomatic AS in pregnancy: BAV in the second trimester as a bridge; TAVI or SAVR reserved for refractory cases (high foetal radiation risk with TAVI).^[1][2]

Frailty is now a formal part of the heart-team assessment. In the FRAILTY-AVR cohort of 1,020 patients (median age 82) the 4-item Essential Frailty Toolset (lower-extremity weakness, cognitive impairment, anaemia, hypoalbuminaemia) was the strongest predictor of death at 1 year after TAVI or SAVR (adjusted odds ratio 3.72).^[27] TAVI is preferred in the over-80s, the frail, and those with hostile chests or prohibitive surgical risk, on the strength of the PARTNER and Evolut data.^{[3][4][5][6][7][16]}

End-stage renal disease accelerates valve calcification, raises surgical risk, and biases choice toward TAVI in suitable anatomy. Outcomes remain worse than in non-renal patients.^[1]

How patients with aortic stenosis come to harm (the preventable list)

• Delaying AVR once symptoms appear — untreated 1-year mortality reaches 50 percent; the window closes.^[15]
• Reading a softening murmur as improvement — it is a failing ventricle, and the patient is referred too late.^[1]
• Treating AS decompensation with vasodilators, aggressive diuresis or beta-blockers — collapsing the underfilled, preload-dependent LV.^[1]
• Missing the bicuspid aortopathy — the valve is replaced and the ascending aorta forgotten, then dissection follows.^[1]
• Failing to confirm low-flow low-gradient AS — pseudo-severe AS does not need AVR, and true-severe AS is missed without dobutamine stress echo or CT calcium.^[2]
• Exercising a symptomatic severe AS patient — contraindicated; syncope, arrhythmia or death can follow.^[1]
• Missing Heyde syndrome — attributing the GI bleed to colonic cancer while the acquired von Willebrand syndrome from the stenotic valve goes untreated.^[22]

The landmark TAVI trials — across the risk spectrum

The TAVI evidence base is one of the most rapidly assembled in cardiology. The major trials established non-inferiority (and in low-risk patients superiority) of TAVI to SAVR across every risk stratum:^[1]

^{[3] [4] [5] [6] [7] [16] [28]}

Statin failure — SEAS and ASTRONOMER

Despite the atherosclerosis-like biology, lipid-lowering does not halt AS:^[8]

• SEAS (Rossebo, NEJM 2008) — simvastatin plus ezetimibe in mild-to-moderate AS — no effect on the primary composite of major cardiovascular events, no reduction in aortic-valve replacement, and no effect on aortic-valve events (ischaemic cardiovascular events were fewer, chiefly less CABG).^[8]
• ASTRONOMER (Chan, Circulation 2010) — rosuvastatin in asymptomatic mild-to-moderate AS — no slowing of haemodynamic progression.^[9]

The lesson: the biology resembles but is not identical to atherosclerosis. Once calcification is established, the valve progresses through mechanisms that lipid lowering does not modify.^[8][9]

Regional guideline differences

^[1]

Prognosis — the symptom threshold is everything

The central prognostic fact in AS is the symptom threshold.^[1]

• Asymptomatic severe AS — survival through the asymptomatic phase matches age-matched controls and sudden death is under 1 percent per year^[1]; but risk rises with Vmax (symptom onset about 50 percent at 2 years in very severe AS, and event-free survival 36 percent at 2 years and 25 percent at 3 years once Vmax reaches 5 m/s)^[18], LVEF decline, BNP elevation and rapid progression.
• Symptomatic severe AS — mean survival after symptom onset in the classical series: angina about 5 years, syncope about 3 years, heart failure about 2 years^[19]; 1-year mortality reaches 50 percent without AVR.^[15]
• After successful AVR — symptoms improve dramatically and valve replacement restores an average life expectancy, reducing mortality towards that of age-matched controls, provided EF recovers and there is no significant paravalvular leak.^[15]
• Follow-up — post-AVR patients need lifelong surveillance with a baseline post-procedural echo and periodic imaging thereafter, plus prosthesis-specific care (anticoagulation for mechanical valves, endocarditis precautions). Asymptomatic severe AS in the community needs 6- to 12-monthly echo with symptom review.^[1]

The take-home rule: once severe AS is symptomatic, AVR should not be delayed — there is no plateau and no medical alternative.^[1]

The mantra, and the viva honesty line

^{[1] [19]}

The mantra: feel the carotid, read the valve area, and replace before the ventricle fails.^[1][2]

Ward-round test — three stems, thirty seconds each

Stem 1 — the dog-walker from the top of the topic (answer)ShowHide

A 74-year-old with a slow-rising pulse, ejection systolic murmur radiating to the carotids, single S2 and an S4, who has stopped walking his dog and felt faint carrying shopping. What is the diagnosis, the severity, and the next step? Model: This is severe symptomatic aortic stenosis — the murmur and pulse are classic, and the exertional pre-syncope with reduced exercise tolerance are symptoms that re-classify him as AVR-indicated regardless of the exact numbers. Confirm severity with transthoracic echocardiography (continuity-equation AVA, Vmax, mean gradient, EF), exclude significant coronary disease with CT or invasive angiography, and refer to the heart team for AVR — SAVR or TAVI by his age (he is over 70), frailty and anatomy. Do not exercise-test him; he is already symptomatic.^[1][2]

Stem 2 — the murmur that went quiet (answer)ShowHide

A 78-year-old with known severe AS returns to clinic. Her daughter says she is "much better — the doctor said the murmur is quieter." She now needs to sit after climbing one flight, and her echo shows EF 42 percent with a mean gradient of 28 mmHg. What has happened, and what is the trap? Model: This is low-flow low-gradient AS with a failing ventricle, not improvement. The murmur and the gradient have softened because the LV can no longer generate flow across the stenotic valve. Confirm true severity with dobutamine stress echo (contractile reserve) or CT aortic calcium score (ESC: severe highly likely above 3000 AU in men). She needs urgent AVR — the softening is a late, dangerous sign, and delaying it for "medical optimisation" costs the window.^[1][2]

Stem 3 — the young athlete with a murmur (answer)ShowHide

A 19-year-old cricketer has an ejection systolic murmur at the left sternal edge that gets louder when he stands up and strains, a jerky bifid pulse, and no radiation to the carotids. What is this, and what must you NOT do? Model: This is hypertrophic obstructive cardiomyopathy, not aortic stenosis — the murmur increases with Valsalva and standing (the opposite of AS), the pulse is jerky not slow-rising, and there is no carotid radiation. Confirm with echocardiography (LV hypertrophy, systolic anterior motion, LVOT gradient). Do not give vasodilators, nitrates or inotropes, and do not diurese aggressively — all worsen LVOT obstruction. Refer to the inherited-cardiac-conditions pathway; beta-blocker or disopyramide for symptoms, septal reduction therapy if refractory.^[1]

References30ShowHide

1. [1]Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines Circulation, 2021.PMID 33332150
2. [2]Vahanian A, Beyersdorf F, Praz F, et al. 2021 ESC/EACTS Guidelines for the management of valvular heart disease Eur Heart J, 2022.PMID 34453165
3. [3]Smith CR, Leon MB, Mack MJ, et al. Transcatheter versus surgical aortic-valve replacement in high-risk patients N Engl J Med, 2011.PMID 21639811
4. [4]Thourani VH, Kodali S, Makkar RR, et al. Transcatheter aortic valve replacement versus surgical valve replacement in intermediate-risk patients: a propensity score analysis Lancet, 2016.PMID 27053442
5. [5]Reardon MJ, van Mieghem NM, Popma JJ, et al. Surgical or Transcatheter Aortic-Valve Replacement in Intermediate-Risk Patients N Engl J Med, 2017.PMID 28304219
6. [6]Popma JJ, Deeb GM, Yakubov SJ, et al. Transcatheter Aortic-Valve Replacement with a Self-Expanding Valve in Low-Risk Patients N Engl J Med, 2019.PMID 30883053
7. [7]Makkar RR, Thourani VH, Mack MJ, et al. Five-Year Outcomes of Transcatheter or Surgical Aortic-Valve Replacement N Engl J Med, 2020.PMID 31995682
8. [8]Rossebø AB, Pedersen TR, Boman K, et al. Intensive lipid lowering with simvastatin and ezetimibe in aortic stenosis N Engl J Med, 2008.PMID 18765433
9. [9]Chan KL, Teo K, Dumesnil JG, et al. Effect of Lipid lowering with rosuvastatin on progression of aortic stenosis: results of the aortic stenosis progression observation: measuring effects of rosuvastatin (ASTRONOMER) trial Circulation, 2010.PMID 20048204
10. [10]Gray A, Goodacre S, Newby DE, et al. Noninvasive ventilation in acute cardiogenic pulmonary edema N Engl J Med, 2008.PMID 18614781
11. [11]Clavel MA, Magne J, Pibarot P. Low-gradient aortic stenosis Eur Heart J, 2016.PMID 27190103
12. [12]Clavel MA, Pibarot P, Dumesnil JG. Paradoxical low flow aortic valve stenosis: incidence, evaluation, and clinical significance Curr Cardiol Rep, 2014.PMID 24343152
13. [13]Tribouilloy C, Lévy F, Rusinaru D, et al. Outcome after aortic valve replacement for low-flow/low-gradient aortic stenosis without contractile reserve on dobutamine stress echocardiography J Am Coll Cardiol, 2009.PMID 19442886
14. [14]Dahou A, Clavel MA, Capoulade R, et al. B-Type Natriuretic Peptide and High-Sensitivity Cardiac Troponin for Risk Stratification in Low-Flow, Low-Gradient Aortic Stenosis: A Substudy of the TOPAS Study JACC Cardiovasc Imaging, 2018.PMID 28917673
15. [15]Otto CM, Newby DE, Hillis GS Calcific Aortic Stenosis: A Review JAMA, 2024.PMID 39527048
16. [16]Mack MJ, Leon MB, Thourani VH, et al. Transcatheter Aortic-Valve Replacement with a Balloon-Expandable Valve in Low-Risk Patients N Engl J Med, 2019.PMID 30883058
17. [17]Kang DH, Park SJ, Lee SA, et al. Early Surgery or Conservative Care for Asymptomatic Aortic Stenosis N Engl J Med, 2020.PMID 31733181
18. [18]Rosenhek R, Zilberszac R, Schemper M, et al. Natural history of very severe aortic stenosis Circulation, 2010.PMID 20026771
19. [19]Ross J, Braunwald E Aortic stenosis Circulation, 1968.PMID 4894151
20. [20]Ring L, Shah BN, Bhattacharyya S, et al. Echocardiographic assessment of aortic stenosis: a practical guideline from the British Society of Echocardiography Echo Res Pract, 2021.PMID 33709955
21. [21]Marcus ML, Doty DB, Hiratzka LF, et al. Decreased coronary reserve: a mechanism for angina pectoris in patients with aortic stenosis and normal coronary arteries N Engl J Med, 1982.PMID 6215582
22. [22]Nawaz S, Rao A, Khan MA, et al. Aortic stenosis severity gradient and gastrointestinal bleeding: Pathophysiological mechanisms, epidemiological evidence, and rationale for a gradient-stratified retrospective study Int J Cardiol, 2026.PMID 42471061
23. [23]Guner A, Havan N, Gunduz S, et al. Evaluation of the congenital supravalvular aortic stenosis by different imaging modalities Echocardiography, 2017.PMID 28681443
24. [24]Giles TD, Martinez EC, Burch GE Gallavardin phenomenon in aortic stenosis. A possible mechanism Arch Intern Med, 1974.PMID 4278106
25. [25]Karagoz U, Kahya Eren N, Ozdemir E, et al. Left Ventricular Hypertrophy Findings on Electrocardiogram Predict Impaired Left Atrial Functions Turk Kardiyol Dern Ars, 2024.PMID 38982819
26. [26]Waggoner AD, Adyanthaya AV, Quinones MA, et al. Left atrial enlargement. Echocardiographic assessment of electrocardiographic criteria Circulation, 1976.PMID 134852
27. [27]Afilalo J, Lauck S, Kim DH, et al. Frailty in Older Adults Undergoing Aortic Valve Replacement: The FRAILTY-AVR Study J Am Coll Cardiol, 2017.PMID 28693934
28. [28]Van Mieghem NM, Deeb GM, Sondergaard L, et al. Self-expanding Transcatheter vs Surgical Aortic Valve Replacement in Intermediate-Risk Patients: 5-Year Outcomes of the SURTAVI Randomized Clinical Trial JAMA Cardiol, 2022.PMID 36001335
29. [29]Brouwer J, Nijenhuis VJ, Delewi R, et al. Aspirin with or without Clopidogrel after Transcatheter Aortic-Valve Implantation N Engl J Med, 2020.PMID 32865376
30. [30]Dangas GD, Tijssen JGP, Wohrle J, et al. A Controlled Trial of Rivaroxaban after Transcatheter Aortic-Valve Replacement N Engl J Med, 2020.PMID 31733180