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Aortic Valvular Stenosis

Basics

  • Narrowing of aortic valve area (AVA) from leaflet fibrosis or calcification causing LV outflow obstruction.
  • Long asymptomatic latency period.
  • Symptoms of severe obstruction: syncope, angina, congestive heart failure (CHF).
  • High mortality without surgical intervention.

Epidemiology

  • Most common acquired valve disease needing surgery in Europe and North America.
  • Causes by age:
  • <30 years: congenital
  • 30–65 years: congenital or rheumatic fever (RF)

  • 65 years: degenerative calcification

  • Prevalence increases with age: 1% in 65–74 years, 2% in 75–84 years, 4% >84 years.
  • Bicuspid aortic valve (1–2% population) predisposes to earlier AS.

Etiology & Pathophysiology

  • LV systolic pressure increases to maintain cardiac output → concentric LV hypertrophy (LVH).
  • LVH reduces coronary perfusion and causes diastolic dysfunction.
  • Loss of LA contraction (e.g., atrial fibrillation) can worsen symptoms.
  • Calcific degeneration follows endothelial dysfunction → inflammation → fibrosis → calcification.
  • Congenital causes: unicuspid, bicuspid, or fused tricuspid valves; hypoplastic annulus.
  • RF causes commissural fusion and scarring.
  • Genetic mutations: NOTCH1, GATA1 linked to bicuspid valve calcification.

Risk Factors

  • Congenital unicommissural or bicuspid valves.
  • Rheumatic fever.
  • Degenerative calcification linked to hypercholesterolemia, hypertension, smoking, diabetes, male sex, age.

Associated Conditions

  • Coronary artery disease (50%)
  • Hypertension (40%)
  • Aortic insufficiency (common with bicuspid and rheumatic valves)
  • Mitral valve disease (95% of rheumatic AS cases)
  • Acquired von Willebrand disease → bleeding (ecchymosis, epistaxis) in 20%
  • GI arteriovenous malformations
  • Calcium embolic stroke risk

Diagnosis

History

  • Angina (most frequent symptom)
  • Exertional syncope
  • CHF symptoms: fatigue, dyspnea, orthopnea, PND
  • Palpitations, TIA/CVA from emboli
  • Symptoms correlate with AVA <1 cm², jet velocity >4 m/s, or mean gradient ≥40 mm Hg.
  • Geriatric patients may present subtly.

Physical Exam

  • Systolic crescendo-decrescendo murmur at 2nd right sternal border radiating to carotids.
  • Murmur peak delays with increasing severity.
  • Possible high-pitched blowing diastolic murmur if aortic insufficiency present.
  • Paradoxical split or absent A2.
  • S4 gallop.
  • Signs: pulsus parvus et tardus, LV heave, signs of CHF.

Differential Diagnosis

  • Mitral regurgitation (pansystolic murmur at apex, radiates to axilla).
  • Hypertrophic obstructive cardiomyopathy (murmur louder with standing/Valsalva).
  • Subaortic stenosis (associated with PDA, VSD, coarctation).
  • Supravalvular stenosis (Williams syndrome, familial hypercholesterolemia).

Diagnostic Tests & Interpretation

Initial Tests

  • Chest X-ray: normal or boot-shaped heart, poststenotic aortic dilatation, valve calcification.
  • ECG: normal or LVH, LA enlargement, nonspecific ST-T changes.

Echocardiography

  • Transthoracic echo is gold standard.
  • Findings: valve thickening/calcification, decreased mobility, reduced AVA, increased gradient.
  • AS severity staging:
  • Stage A (at risk): jet velocity <2 m/s
  • Stage B (mild to moderate): 2–3.9 m/s velocity
  • Stage C (severe asymptomatic): AVA ≤1 cm², velocity ≥4 m/s
  • Stage D (severe symptomatic): gradient >40 mm Hg, symptoms present.

Other Tests

  • Exercise stress test: to reveal symptoms in asymptomatic severe AS.
  • Dobutamine stress echo: in low-flow low-gradient AS with LV dysfunction.
  • Cardiac catheterization: pre-op CAD evaluation and valve gradient measurement.
  • CT calcium scoring: helps confirm severity in low-flow AS.

Treatment

Medical

  • No effective medical therapy for severe/symptomatic AS.
  • Statins, PCSK9 inhibitors, lipoprotein(a) lowering agents studied but not proven.
  • Antibiotic prophylaxis for rheumatic AS (penicillin G IM q4wks).
  • ACE inhibitors cautiously used for comorbid hypertension.
  • Avoid vasodilators due to risk of hypotension.

Surgical

  • Aortic valve replacement (AVR) is definitive for symptomatic severe AS.
  • Indications for AVR:
  • Symptomatic severe AS with low/intermediate surgical risk.
  • Asymptomatic severe AS with LVEF <50%.
  • Severe AS undergoing other cardiac surgery.
  • Transcatheter AVR (TAVR) is alternative for high/intermediate risk or older patients.
  • Balloon valvuloplasty: palliative or bridge in unstable/high-risk patients.

Ongoing Care & Follow-up

  • Monitor symptoms (angina, syncope).
  • Serial echocardiograms: yearly for severe, 1–2 years for moderate, 3–5 years for mild AS.
  • Physical activity:
  • Mild AS: no restrictions.
  • Moderate to severe AS: avoid strenuous exercise.
  • Exercise stress test recommended before starting exercise program.

Prognosis

  • Asymptomatic patients have near-normal survival.
  • Symptomatic patients without AVR have poor prognosis:
  • 25% annual mortality.
  • Average survival 2–3 years.
  • Perioperative mortality:
  • AVR alone: ~4%
  • AVR + CABG: ~6.8%
  • Poor prognostic factors: advanced age, NYHA class III/IV, cerebrovascular disease, renal dysfunction, CAD.

Clinical Pearls

  • Diagnosed clinically by systolic crescendo-decrescendo murmur and delayed carotid pulse.
  • Classic symptoms: angina, syncope, heart failure.
  • Surgical intervention critical for symptomatic AS to prevent mortality.