Aortic stenosis is the most prevalent valvular heart disease in elderly adults, characterized by progressive narrowing of the aortic valve orifice, which causes left ventricular outflow tract obstruction, elevated left ventricular pressure, and eventual left ventricular hypertrophy, heart failure, and sudden cardiac death. It is classified by etiology: calcific degenerative AS (~80% of adult cases), congenital bicuspid aortic valve (BAV)-related AS (~10-15% of cases), and rheumatic AS (still prevalent in developing regions).

• Etiology: Degenerative calcific AS is driven by age-related atherosclerotic processes, including lipid accumulation, inflammation, and progressive leaflet calcification. BAV, the most common congenital heart defect, causes accelerated stenosis onset 10-20 years earlier than tricuspid aortic valves. Rheumatic AS results from post-rheumatic fever commissural fusion and scarring.
• Clinical Manifestations: Early AS is asymptomatic for decades. The classic symptomatic triad includes exertional dyspnea (heart failure), angina pectoris, and syncope. Symptomatic severe AS has a 50% 2-year mortality rate without intervention, with advanced disease presenting with severe heart failure, arrhythmias, and sudden cardiac death.
• Diagnosis: TTE is the first-line gold standard, quantifying aortic valve area (AVA), mean transvalvular gradient, peak jet velocity, and left ventricular structure and function. Severe AS is defined as AVA <1.0 cm², mean gradient ≥40 mmHg, or peak velocity ≥4.0 m/s. Cardiac CTA and TEE are used for pre-procedural planning for transcatheter intervention.

• Conservative Management: Indicated for asymptomatic mild-moderate AS, with serial echocardiographic surveillance (every 1-5 years based on severity), cardiovascular risk factor modification, and comorbidity management. No medical therapy has been proven to halt or reverse calcific AS progression.
• Surgical Aortic Valve Replacement (SAVR): The historical gold standard for severe symptomatic AS in low-to-moderate surgical risk patients, involving sternotomy, cardiopulmonary bypass, and replacement with a mechanical or bioprosthetic valve. SAVR has a 30-day mortality rate <2% in low-risk patients, with excellent long-term outcomes.
• Transcatheter Aortic Valve Replacement (TAVR): A minimally invasive catheter-based procedure (most commonly transfemoral access) that eliminates the need for sternotomy or cardiopulmonary bypass. Initially for inoperable/high-risk patients, TAVR is now the first-line guideline-recommended treatment for severe symptomatic AS across all risk strata.
• Balloon Aortic Valvuloplasty (BAV): A palliative procedure for temporary hemodynamic stabilization in critically ill patients, or as a bridge to TAVR/SAVR, with limited long-term efficacy due to rapid restenosis.