Aortic Stenosis

Aortic stenosis is obstruction of left ventricular outflow at the aortic valve, producing pressure overload and concentric hypertrophy.

Causes: calcific degeneration of a trileaflet valve (commonest, over 65 years), bicuspid aortic valve (presents 50 to 70), rheumatic disease.

Prevalence is about 3% over age 75, with severe disease in 3.4% of those over 75.

Severity: severe when peak velocity 4.0 m/s or more, mean gradient 40 mmHg or more, valve area 1.0 cm2 or less (0.6 cm2/m2 indexed). Low flow, low gradient variants need dobutamine stress echo or CT calcium scoring (men over 2000 AU, women over 1200 AU).

Natural history: after symptom onset, survival is 2 to 3 years for angina or syncope and 1 to 2 years for heart failure without intervention.

• Classic triad: exertional angina, syncope or presyncope, heart failure symptoms.
• Harsh crescendo decrescendo ejection systolic murmur at the right upper sternal border radiating to the carotids; late peaking murmur, soft or absent S2, slow rising pulse (pulsus parvus et tardus), sustained apical impulse.
• Gastrointestinal bleeding from angiodysplasia (Heyde syndrome) due to acquired von Willebrand syndrome.
• Sudden death in symptomatic disease.

• Echocardiography: valve morphology, velocity, gradient, area, left ventricular function and hypertrophy.
• ECG: left ventricular hypertrophy with strain, conduction disease.
• Low flow low gradient: dobutamine stress echo; CT calcium score.
• Coronary angiography or CT angiography before intervention.
• Cardiac CT for annular sizing, access routes (TAVI planning).
• BNP, exercise testing in asymptomatic severe disease (exercise testing is contraindicated if symptomatic).
• Heart team assessment with STS or EuroSCORE II.

• No medical therapy slows progression. Treat hypertension carefully (ACE inhibitor started low), manage atrial fibrillation, heart failure with diuretics cautiously. Avoid vasodilators and dehydration.
• Aortic valve replacement indications:
  • Symptomatic severe stenosis (class I).
  • Asymptomatic severe with ejection fraction under 50%, abnormal exercise test, very severe stenosis (velocity 5 m/s or more), rapid progression (0.3 m/s per year), rising BNP; early intervention supported by trials (EARLY TAVR, AVATAR).
  • Undergoing other cardiac surgery.
• Choice of procedure:
  • Surgical AVR (age under 65 or life expectancy over 20 years, bicuspid anatomy, need for other surgery, unsuitable TAVI anatomy). Mechanical valve needs warfarin (INR 2.5 to 3.5); bioprosthesis may need aspirin 75 to 100 mg.
  • Transcatheter AVR (age over 75, high surgical risk, or per heart team in the 65 to 80 group), transfemoral preferred; pacemaker rate 10 to 20%, stroke 1 to 3%, paravalvular leak.
  • Balloon valvuloplasty as a bridge in unstable patients.
• Post procedure: endocarditis prophylaxis, antiplatelet therapy after TAVI (aspirin 75 to 100 mg), echo follow up, dental hygiene, treat hypertension.