Aortic Stenosis

Table of Contents

  1. Overview
  2. Epidemiology
  3. Pathophysiology
  4. Etiology and Grading
  5. Classic Symptomatic Triad
  6. Diagnosis
  7. Medical Management
  8. TAVR (Transcatheter Aortic Valve Replacement)
  9. SAVR (Surgical Aortic Valve Replacement)
  10. Bicuspid Aortic Valve and Aortopathy
  11. Complications and Prognosis
  12. Research Papers
  13. Connections
  14. Featured Videos

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1. Overview

Aortic stenosis (AS) is the most common valvular heart disease in developed countries and the most common valvular cause of cardiac surgery. It involves progressive narrowing of the aortic valve orifice, obstructing left ventricular (LV) outflow. The three primary etiologies are calcific/degenerative disease (adults >65), bicuspid aortic valve (BAV — adults 40–60, affecting 1–2% of the population), and rheumatic disease.

Severe AS is defined by a valve area <1.0 cm², peak jet velocity ≥4 m/s, and mean gradient ≥40 mmHg. Once symptoms appear, clinical deterioration is rapid and survival is markedly reduced without intervention. Transcatheter aortic valve replacement (TAVR) has revolutionized management for patients across all surgical risk strata, transforming AS from a near-universally lethal condition in poor surgical candidates to one with broadly available effective treatment options.

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2. Epidemiology

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3. Pathophysiology

Calcific Aortic Stenosis

The pathogenesis of calcific AS shares features with atherosclerosis: endothelial injury leads to lipid infiltration, followed by local inflammation, oxidative stress, and progressive calcium deposition on valve leaflets. Risk factors overlap significantly with those for coronary artery disease — age, male sex, hypertension, hyperlipidemia, diabetes, and smoking all accelerate valve calcification.

Leaflet stiffening and reduced valve opening area create an increasing transvalvular pressure gradient. The LV compensates with concentric hypertrophy (pressure overload pattern): sarcomeres added in parallel increase wall thickness while cavity dimensions remain relatively unchanged, normalizing wall stress per the Laplace law. Over time, this compensatory hypertrophy leads to diastolic dysfunction (a stiff, non-compliant LV), and eventually to systolic dysfunction when afterload exceeds the LV's compensatory capacity — a phenomenon called afterload mismatch.

Concentric hypertrophy also reduces coronary reserve: thickened walls compress intramural coronary vessels, and the hypertrophied myocardial mass demands more oxygen than the coronary circulation can supply during stress. This explains why angina is common in severe AS even in the absence of obstructive coronary artery disease. When ventricular output falls critically, systemic vascular resistance rises and cardiogenic shock can ensue.

Bicuspid Aortic Valve (BAV)

BAV most commonly results from abnormal fusion of the right and left cusps (less often the right and non-coronary cusps). Turbulent, asymmetric transvalvular flow accelerates leaflet degeneration and calcium deposition, typically producing severe AS 10–20 years earlier than in patients with a tricuspid aortic valve (median age 60–65 vs. 75–80 years). BAV is also independently associated with aortopathy — medial degeneration of the aortic wall driven by abnormal NOTCH1 signaling and fibrillin-1 deficiency — not solely by hemodynamic turbulence.

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4. Etiology and Grading

Etiology

Grading by 2021 AHA/ACC Valvular Heart Disease Guideline

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5. Classic Symptomatic Triad

The landmark natural history data established by Ross and Braunwald in 1968 define expected survival once each symptom of severe AS appears. Before symptoms develop, the prognosis is relatively good. Symptom onset signals LV decompensation and marks a critical inflection in prognosis:

Physical Examination Findings

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6. Diagnosis

Echocardiography (Primary Diagnostic Tool)

Transthoracic echocardiography with Doppler is the standard first-line investigation. Key measurements include:

CT Calcium Scoring

Aortic valve calcium (AVC) scoring by CT is important for TAVR planning and for confirming severity in low-gradient AS. An Agatston score >3,000 in men or >1,600 in women strongly supports severe AS regardless of gradient. CT also provides annular sizing critical for TAVR prosthesis selection.

Cardiac Catheterization

Direct measurement of the transvalvular gradient via simultaneous aortic and LV pressure measurement is reserved for cases where echocardiography and CT are discordant, or for pre-SAVR coronary angiography. Coronary CT angiography (CCTA) is increasingly used for pre-TAVR coronary assessment to reduce procedural risk.

Cardiac MRI (CMR)

CMR quantifies LV fibrosis via late gadolinium enhancement — a predictor of post-intervention recovery and long-term outcomes. CMR also provides precise aortic root and ascending aortic dimensions in BAV aortopathy and accurate AVA planimetry when echocardiography is technically limited.

Additional Studies

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7. Medical Management

There is currently no proven pharmacologic therapy that slows AS progression or improves outcomes in asymptomatic severe AS. Management is focused on cardiovascular risk factor control, monitoring for symptom onset, and optimal timing of valve intervention.

Echocardiographic Surveillance Intervals

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8. TAVR (Transcatheter Aortic Valve Replacement)

TAVR involves percutaneous delivery and deployment of a bioprosthetic valve within the diseased native aortic valve, eliminating the need for open-heart surgery. The PARTNER (Placement of Aortic Transcatheter Valves) trial series has provided the definitive evidence base across all surgical risk groups:

Current Indications (2021 AHA/ACC Guideline)

TAVR Complications

TAVR Durability

Long-term structural valve deterioration (SVD) data are accumulating. Five-year outcomes from PARTNER trials show low rates of clinically significant SVD. Landmark 10-year TAVR durability data — including the FRANCE TAVI and CoreValve/Evolut registries — demonstrate generally favorable durability for patients with intermediate or high surgical risk. For younger patients requiring longer valve lifetimes, valve durability remains an area of active investigation.

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9. SAVR (Surgical Aortic Valve Replacement)

Surgical aortic valve replacement via median sternotomy and cardiopulmonary bypass remains the gold standard for:

Prosthesis Choice

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10. Bicuspid Aortic Valve and Aortopathy

BAV is the most common congenital cardiac malformation, present in 1–2% of the population. Its clinical importance extends beyond valve disease to thoracic aortic aneurysm and dissection risk. Aortopathy affects up to 50% of BAV patients and is driven by intrinsic aortic wall weakness from NOTCH1 pathway mutations and abnormal smooth muscle cell function — independent of hemodynamic turbulence from the valve itself.

Aortopathy Screening and Management

Genetics and Family Screening

BAV is heritable with an autosomal dominant pattern with variable penetrance; 5–10% of first-degree relatives have BAV. Echocardiographic screening of all first-degree relatives is recommended at diagnosis. Genetic testing for NOTCH1, GATA5, and ROBO4 mutations is emerging but not yet standard of care outside research settings. TAVR in BAV-AS is technically more challenging (asymmetric annulus, leaflet morphology) and historically excluded from major trials, though contemporary data and dedicated BAV TAVR techniques show increasingly favorable results.

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11. Complications and Prognosis

Natural History Without Intervention

Untreated symptomatic severe AS carries an extremely poor prognosis: approximately 50% 2-year mortality and 75% 5-year mortality from symptom onset. Sudden cardiac death accounts for approximately 15% of AS-related deaths and can occur even in previously asymptomatic patients, particularly those with very severe gradients or rapid hemodynamic progression.

Post-Intervention Prognosis

With successful TAVR or SAVR, survival approaches age-matched population norms in intermediate- and high-risk patients. In PARTNER 3 (low-risk patients), 5-year outcomes confirm durable survival benefit for both TAVR and SAVR over prior medical therapy benchmarks. The primary determinants of long-term post-intervention prognosis include pre-existing LV dysfunction, degree of LV reverse remodeling (regression of hypertrophy and recovery of EF), and comorbidities (AF, chronic kidney disease, frailty).

Major Complications

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Research Papers

The following PubMed topic searches return current peer-reviewed literature relevant to aortic stenosis. Each link opens a live PubMed query.

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Connections

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