What is the recommended treatment for a patient with a dimensional index of 0.35 indicating moderate to severe aortic stenosis?

Management of Aortic Stenosis with Dimensional Index of 0.35

For patients with a dimensional index of 0.35 indicating moderate to severe aortic stenosis, aortic valve replacement (AVR) is recommended, particularly if the patient is symptomatic or has other high-risk features. 1, 2

Understanding the Dimensional Index in Aortic Stenosis

A dimensional index (velocity ratio) of 0.35 falls within the moderate aortic stenosis range according to current guidelines:

• Severe AS: velocity ratio <0.25
• Moderate AS: velocity ratio 0.25-0.50
• Mild AS: velocity ratio >0.50 1

This corresponds with other parameters for moderate-to-severe aortic stenosis:

• AVA between 0.60-0.85 cm²/m² (indexed)
• Mean gradient between 20-40 mmHg
• Peak velocity between 3.0-4.0 m/s 1

Treatment Algorithm Based on Symptom Status

For Symptomatic Patients:

1. Symptomatic patients with moderate-to-severe AS (dimensional index 0.35):

   • AVR is strongly recommended (Class I recommendation) 1, 2
   • Choice between TAVR vs. SAVR depends on surgical risk:
     • High/intermediate risk: Either TAVR or SAVR is appropriate 2
     • Low surgical risk: SAVR is preferred, especially in younger patients 2, 3

2. Pre-operative management while awaiting surgery:

   • Target heart rate ≤60 beats per minute
   • Maintain systolic blood pressure between 100-120 mmHg
   • Consider beta blockers for rate control
   • Restrict physical activity 2

For Asymptomatic Patients:

1. Asymptomatic with moderate-to-severe AS (dimensional index 0.35):

   • Watchful waiting with close monitoring is generally recommended 4
   • Serial echocardiography every 6-12 months 4

2. Consider early AVR if any of these high-risk features are present:

   • Moderate to severe valve calcification
   • Rapid progression (increase in velocity ≥0.3 m/s per year)
   • Reduced left ventricular ejection fraction (<50%)
   • Very severe AS (peak velocity ≥5 m/s or mean gradient ≥60 mmHg)
   • Abnormal exercise test (symptoms, hypotension, or limited exercise capacity) 1, 2, 5

Special Considerations

1. Low-flow, low-gradient AS with preserved EF:

   • If dimensional index is 0.35 but other parameters are discordant (AVA <1.0 cm² with mean gradient <40 mmHg)
   • Additional testing may be needed:
     • Calcium scoring by CT to confirm severity
     • Careful exclusion of measurement errors 1, 2

2. Low-flow, low-gradient AS with reduced EF:

   • Dobutamine stress echocardiography to distinguish true severe AS from pseudo-severe AS
   • AVR is appropriate if AS is confirmed to be truly severe 1, 2

Prognostic Implications

Without intervention, patients with moderate-to-severe AS face significant mortality risk:

• Survival rates in untreated symptomatic patients are poor, with 1-year survival of 67%, 2-year survival of 56%, and 5-year survival of 38% 6
• Even asymptomatic patients with moderate-to-severe calcification have poor event-free survival (60% at 1 year, 47% at 2 years) 5

Pitfalls and Caveats

1. Symptom assessment challenges:

   • Symptoms may be subtle or attributed to aging
   • Exercise testing may be valuable to unmask symptoms in apparently asymptomatic patients 1

2. Measurement accuracy:

   • Ensure proper measurement of LVOT diameter to avoid underestimation of flow
   • Confirm consistency between multiple parameters of stenosis severity 1

3. Concurrent conditions:

   • Hypertension can alter gradient measurements and should be controlled during assessment
   • Concurrent coronary artery disease may require simultaneous intervention 1, 4

4. Medical therapy limitations:

   • No medical therapy has been proven to halt progression of AS
   • Vasodilators must be used with extreme caution in severe AS due to risk of dangerous hypotension 2, 7

By following this algorithm and considering these factors, appropriate management decisions can be made for patients with aortic stenosis with a dimensional index of 0.35.