Ep 170 – Aortic stenosis

Aortic stenosis (AS) is an obstruction of blood flow from the left ventricle into the aorta due to narrowing at the level of the aortic valve. In Europe, it is the most common valvular disease requiring treatment and is the second most frequent cause for cardiac surgery. By the age of 80, it occurs in almost 10% of adults and has a mortality rate of about 50% at 2 years unless the outflow obstruction is relieved. In this episode, Dr Roger Henderson looks at the aetiology, pathophysiology, clinical presentation, diagnostic evaluation, treatment options and prognosis associated with this common condition usually seen in our elderly patients.

Key take-home points

• AS is essentially an obstruction of blood flow from the left ventricle into the aorta due to narrowing at the aortic valve.
• It is no longer thought to reflect simple age-related wear and tear, but is recognised as an active and progressive process.
• Calcification and fibrosis of normal trileaflet valves is the most common cause of AS in adults and accounts for as many as 80% of cases, with congenitally bicuspid valves accounting for most of the remainder.
• AS is the most common valvular disease requiring treatment in the US and Europe and is the second most frequent cause for cardiac surgery.
• By the age of 80, it occurs in almost 10% of adults and has a mortality rate of about 50% at 2 years unless the outflow obstruction is relieved.
• The clinical manifestations of AS follow a well-recognised triad: dyspnoea on exertion, angina and syncope.
• These symptoms typically do not appear until the disease is advanced, often after a latent period of one to two decades during which the patient may be entirely asymptomatic.
• The typical murmur of AS is a systolic murmur at or greater than grade 3, with a diamond-shaped crescendo–decrescendo pattern that peaks in mid-systole and radiates to the carotid arteries.
• An electrocardiogram is indicated in the initial work-up of all patients and is abnormal in at least 90% of those with AS, with the most common abnormality being left ventricular hypertrophy due to pressure overload.
• Transthoracic echocardiography remains the gold-standard test and is essential for the diagnosis of AS, since it can reliably and accurately detect the presence of a pressure gradient across the aortic valve as well as assessing left ventricle function and the presence of hypertrophy.
• The management is largely surgical, and NICE recommends referral to a specialist for adults with moderate or severe AS, or bicuspid aortic valve disease of any severity (including mild disease).
• No medical therapy has been shown to halt or reverse the progression of valve narrowing, including statin treatment.
• Once symptoms appear, the prognosis without valve replacement is poor, with the average survival dropping to 1–3 years.
• Trans-catheter aortic valve implantation (TAVI) has revolutionised care for intermediate-risk and high-risk patients, offering comparable or superior outcomes to surgical aortic valve replacement with reduced recovery times.
• The 1-year survival rates following TAVI range from 60 to 80%, and the majority of survivors experience a significant improvement in quality of life.

Key references

1. NICE. 2021. https://www.nice.org.uk/guidance/ng208.
2. Vahanian A, et al. Eur Heart J. 2022;43(7):561-632. doi: 10.1093/eurheartj/ehab395.
3. NICE. 2018. https://www.nice.org.uk/guidance/ipg624.
4. Czarny MJ, Resar JR. Clin Med Insights Cardiol. 2014;8(Suppl 1):15-24. doi: 10.4137/CMC.S15716.
5. NICE. 2017. https://www.nice.org.uk/guidance/ipg586.
6. Smith CR, et al. N Engl J Med. 2011;364(23):2187-98. doi: 10.1056/NEJMoa1103510.