Aortic Stenosis: An Evidence-Based Approach

Background

Aortic stenosis (AS) is the narrowing of the aortic valve orifice, obstructing blood flow from the left ventricle into the aorta during systole. This results in increased left ventricular pressure, concentric hypertrophy, and eventually left ventricular dysfunction. If untreated, AS can lead to syncope, angina, heart failure, and sudden cardiac death.

Classification / Types

By Etiology:

• Calcific (Degenerative) AS: Most common in the elderly due to progressive calcium deposition on a trileaflet valve.
• Bicuspid Aortic Valve (Congenital): Predisposes to early calcification and stenosis; often presents before age 65.
• Rheumatic AS: Rare in high-income countries; commissural fusion from rheumatic fever.
• Radiation-Induced AS: Post mediastinal radiation leading to fibrosis and calcification.

By Severity (Based on Echocardiographic Criteria).

Epidemiology

• Sex: More common in males (especially bicuspid valve).
• Age: Degenerative AS typically manifests >65 years old.
• Geography: Degenerative AS common in high-income countries; rheumatic causes still present in low- and middle-income regions.
• Comorbidities: Often coexists with hypertension, coronary artery disease, and diabetes.

Pathophysiology

Progressive outflow obstruction raises left ventricular systolic pressure, driving concentric hypertrophy to preserve wall stress. Over time, the hypertrophied ventricle develops diastolic dysfunction, subendocardial ischemia, and — late in the disease — systolic failure. Fixed cardiac output explains the classical triad of exertional angina, syncope, and dyspnea.

Etiology

• Calcific degeneration of a normal or bicuspid valve
• Congenital bicuspid aortic valve
• Rheumatic heart disease
• Prior chest radiation
• Rare: systemic conditions (e.g., Paget disease, end-stage renal disease with hyperparathyroidism)

Risk Factors

• Age >65 years
• Congenital bicuspid aortic valve
• Rheumatic fever history
• Male sex
• Hyperlipidemia
• Smoking
• Hypertension
• Chronic kidney disease

Clinical Presentation

History (Symptoms)

Often asymptomatic until severe. The classic triad, when symptomatic:

• Angina: Due to increased myocardial oxygen demand and decreased perfusion.
• Syncope: Especially on exertion from fixed cardiac output.
• Dyspnea / heart failure symptoms: From elevated LVEDP and pulmonary congestion.

Other symptoms:

• Fatigue
• Dizziness
• Decreased exercise tolerance
• Sudden cardiac death (rare, advanced cases)

Physical Exam (Signs)

Vital Signs:

• Narrow pulse pressure
• Delayed and diminished carotid upstroke (pulsus parvus et tardus)

Cardiac Exam:

• Harsh crescendo-decrescendo systolic murmur at the right upper sternal border, radiating to the carotids
• S4 gallop (due to a stiff LV)
• Soft or absent A2 (delayed aortic valve closure)
• Paradoxical splitting of S2

Pulmonary: rales in advanced heart failure.

Peripheral: cool extremities and low-output signs; peripheral edema late in the course.

Differential Diagnosis

• Hypertrophic obstructive cardiomyopathy (HOCM)
• Subaortic stenosis
• Mitral regurgitation
• Aortic sclerosis (no obstruction)
• Pulmonary embolism (if presenting with syncope)
• Anemia (if exertional symptoms are out of proportion)

Diagnostic Testing

Initial Tests

• Transthoracic Echocardiogram (TTE): determines severity (valve area, gradients, velocity); assesses LV function, wall thickness, and aortic root.
• Electrocardiogram (ECG): LV hypertrophy, left atrial enlargement, possible conduction abnormalities (e.g., LBBB).
• Chest X-ray: post-stenotic dilation of the ascending aorta; pulmonary congestion in decompensated heart failure.
• BNP / NT-proBNP: elevated in symptomatic or decompensated patients.
• Cardiac CT (calcium scoring): when echo is inconclusive, particularly for valve morphology.
• Cardiac catheterization: confirms severity if noninvasive data is conflicting; assesses coronary anatomy preoperatively.

Treatment

Medical Management

There is no medical therapy proven to halt disease progression; management focuses on symptom control and timely intervention.

• Diuretics for pulmonary congestion (use cautiously to avoid hypotension).
• Beta-blockers or ACE inhibitors for comorbid conditions (e.g., hypertension, CAD) — use cautiously in severe AS.
• Statins for concomitant atherosclerotic disease (not shown to slow AS progression).

Interventional / Surgical

• Surgical Aortic Valve Replacement (SAVR): symptomatic severe AS, asymptomatic with EF <50%, or undergoing other cardiac surgery.
• Transcatheter Aortic Valve Replacement (TAVR): severe symptomatic AS in high-risk or inoperable candidates; increasingly used in intermediate- and low-risk patients.
• Balloon Aortic Valvuloplasty: temporary measure in select non-surgical patients (e.g., bridge to TAVR).

Consults

• Cardiology: all moderate to severe AS, or symptomatic patients.
• Cardiothoracic Surgery: for SAVR evaluation.
• Interventional Cardiology: for TAVR eligibility.
• Anesthesiology: pre-op evaluation if surgery planned.
• Primary Care: comorbidity optimization.

Patient Education, Screening, Vaccines

• Educate on symptoms that warrant urgent evaluation: syncope, worsening dyspnea, chest pain.
• Emphasize regular follow-up and imaging.
• Avoid strenuous activity in symptomatic patients.
• Limit salt intake if volume overload is present.
• Maintain good dental hygiene to reduce endocarditis risk.

Vaccinations:

• Annual influenza vaccine
• Pneumococcal vaccination
• COVID-19 vaccination

Follow-Up

Echocardiography cadence:

• Mild AS: every 3–5 years
• Moderate AS: every 1–2 years
• Severe AS: every 6–12 months (or sooner if symptomatic)

• Monitor for symptom development (dyspnea, angina, syncope).
• Assess LV function and new conduction abnormalities.
• Reevaluate for valve intervention as disease progresses.
• Optimize cardiovascular risk factors (BP, lipids, diabetes).

Published in HMD MedDigest — Substance Over Noise. Written for working physicians, by working physicians.