What is the recommended approach for a patient with moderate aortic stenosis, considering Transcatheter Aortic Valve Implantation (TAVI) as a treatment option?

TAVI is NOT Recommended for Moderate Aortic Stenosis

TAVI should only be performed in patients with confirmed severe aortic stenosis, not moderate stenosis, according to current evidence-based guidelines. 1, 2, 3

Severity Confirmation Required

Current guidelines explicitly restrict TAVI to severe aortic stenosis, defined by specific hemodynamic criteria 1, 3:

• Aortic valve area ≤1.0 cm² 4, 3
• Mean gradient ≥40 mmHg 4, 3
• Peak velocity ≥4.0 m/sec 4, 3

Moderate aortic stenosis does not meet these thresholds and therefore does not qualify for TAVI under any current guideline recommendation 3.

The Only Exception: Concomitant Cardiac Surgery

The sole scenario where moderate AS may warrant intervention is when the patient requires CABG or surgery on the ascending aorta or another valve 1:

• Surgical aortic valve replacement (SAVR) should be considered for moderate AS during concomitant cardiac surgery after Heart Team discussion (Class IIa, Level C) 1
• This recommendation applies to SAVR, not TAVI 1
• The decision requires multidisciplinary Heart Team agreement 1

Management of Moderate Aortic Stenosis

For patients with moderate aortic stenosis who do not require other cardiac surgery 3:

• Conservative management with surveillance is recommended 3
• Serial echocardiography every 1-2 years 3
• Monitor for symptom development or progression to severe stenosis 3
• Intervention is only indicated if stenosis progresses to severe and symptoms develop 3

Why TAVI Requires Severe Stenosis

The evidence base for TAVI exclusively studied severe symptomatic aortic stenosis 1, 2, 5:

• All landmark TAVI trials (PARTNER, Evolut) enrolled only patients with severe AS 6, 7, 5
• TAVI achieves a final valve area of 1.5-1.8 cm², which represents resolution of severe obstruction but would be unnecessary for moderate stenosis 2
• The procedural risks (stroke 3-9%, vascular complications 10-15%, pacemaker requirement up to 24%) cannot be justified without severe stenosis 2, 4

Emerging Research Context

While TAVI is being explored for moderate AS combined with heart failure with reduced ejection fraction in clinical trials, this remains investigational and is not yet guideline-recommended 6:

• Current trials are examining moderate AS with HFrEF as a specific research question 6
• No published guidelines recommend TAVI for isolated moderate AS 1, 3
• Until trial results demonstrate benefit, the standard of care remains observation 3

Critical Pitfall to Avoid

Do not confuse "low-gradient" severe AS with moderate AS 1, 4:

• Patients with low-flow, low-gradient AS may appear to have moderate stenosis by gradient alone 1, 4
• Perform dobutamine stress echocardiography to differentiate true severe from pseudo-severe stenosis 1, 4, 3
• If mean gradient rises >40 mmHg with dobutamine, this confirms severe AS and TAVI becomes appropriate 4