Management and Prognosis of Severe Aortic Stenosis
Without intervention, severe aortic stenosis carries a poor prognosis with high mortality rates, but timely valve replacement (surgical or transcatheter) dramatically improves survival and should be offered to all symptomatic patients regardless of age.
Natural History and Prognosis
Severe aortic stenosis follows a predictable disease course with important prognostic implications:
Symptomatic severe AS: Average survival without intervention is extremely poor:
- 2 years after onset of heart failure symptoms
- 3 years after syncope
- 5 years after angina 1
Asymptomatic severe AS: While traditionally considered more benign, observational data shows 5-year survival rates of only 38% in non-operated patients versus 90% in those receiving valve replacement 2
Diagnosis and Assessment of Severity
Severe aortic stenosis is defined by:
| Parameter | Severe AS Threshold |
|---|---|
| Valve area | <1.0 cm² |
| Mean gradient | ≥40 mmHg |
| Maximum velocity | ≥4 m/s |
Management Algorithm
1. Symptomatic Severe AS
All symptomatic patients with severe AS should be evaluated for valve intervention, as medical therapy alone is associated with poor outcomes.
First-line treatment: Aortic valve replacement (AVR) - either surgical (SAVR) or transcatheter (TAVI/TAVR) 1, 3
Decision between SAVR vs. TAVI based on:
a) Age:
- <65 years: SAVR preferred
- 65-75 years: SAVR generally preferred over TAVI
80 years: TAVI preferred 1
b) Surgical risk:
- STS-PROM >8%: TAVI preferred
- STS-PROM ≤8%: Either SAVR or TAVI appropriate 1
- Prohibitive surgical risk: TAVI is standard of care 4
c) Valve selection (if SAVR chosen):
- <50 years: Mechanical valve
- 50-60 years: Mechanical preferred over bioprosthetic
- 60-65 years: Either mechanical or bioprosthetic
65 years: Bioprosthetic valve 1
2. Asymptomatic Severe AS
Even asymptomatic severe AS carries significant mortality risk and should be closely monitored with consideration for early intervention in specific scenarios.
AVR is recommended for asymptomatic severe AS with:
- Reduced LVEF (<50%) not due to other causes
- Very severe AS (Vmax >5 m/s or mean gradient >60 mmHg)
- Abnormal exercise test
- Rapid progression (increase in Vmax >0.3 m/s/year) 1, 3
3. Special Considerations
Low-Flow, Low-Gradient AS with Reduced LVEF (<50%)
- Dobutamine stress echocardiography needed to distinguish true-severe from pseudo-severe AS
- If true-severe AS confirmed, valve intervention recommended 1
Low-Flow, Low-Gradient AS with Preserved LVEF
- Careful confirmation of AS severity essential
- Intervention recommended if AS is the most likely cause of symptoms 1
Medical Management While Awaiting Intervention
While medical therapy is not a substitute for valve replacement, the following may be used while awaiting definitive intervention:
- First-line agents: ACE inhibitors/ARBs (start at low doses and titrate gradually) 3
- Second-line agents: Beta-blockers (particularly beneficial with concurrent CAD) 3
- Use with caution:
- Diuretics (may excessively reduce preload)
- Non-dihydropyridine calcium channel blockers (may worsen outcomes)
- Alpha blockers (increased cardiovascular events) 3
Monitoring and Follow-up
- Severe AS: Echocardiographic assessment every 6 months
- Moderate AS: Echocardiographic assessment every 12 months 3
Clinical Pitfalls to Avoid
Misattributing symptoms: Patients often subconsciously reduce activities to avoid symptoms - careful questioning is critical 3
Delaying intervention: The notion that asymptomatic severe AS has a benign prognosis is outdated - mortality is significantly higher without intervention 2
Overlooking low-flow states: Low-gradient severe AS with preserved LVEF requires careful confirmation of severity 1
Inappropriate activity recommendations: Restrict physical activity in moderate to severe AS; avoid competitive sports 3
Excessive afterload reduction: Maintain adequate preload; avoid medications that can cause excessive vasodilation 3