How to label and treat a patient with severe low-gradient aortic stenosis, preserved Left Ventricular Ejection Fraction (LVEF), and chronic kidney disease, who is fragile?

Management of Low-Gradient Severe Aortic Stenosis with Preserved LVEF in a Fragile Patient with CKD

For a fragile patient with chronic kidney disease and severe low-gradient aortic stenosis with preserved left ventricular ejection fraction, transcatheter aortic valve replacement (TAVR) is recommended after careful confirmation of true stenosis severity using multimodality imaging.

Diagnostic Classification

This patient presents with what is classified as "paradoxical low-flow, low-gradient severe aortic stenosis with preserved LVEF" (HAVEC stage D3), characterized by:

• Aortic valve area <1.0 cm² (by continuity equation)
• Mean pressure gradient <40 mmHg
• Preserved LVEF (≥50%)
• Low stroke volume index (<35 mL/m²)

This entity is recognized in both European and American guidelines 1 and represents a challenging diagnostic and therapeutic scenario.

Confirming True Stenosis Severity

Before proceeding with intervention, it's essential to confirm that this is truly severe AS:

1. Rule out measurement errors:

   • Verify LVOT diameter measurements
   • Ensure proper Doppler alignment
   • Confirm AVA calculation methodology

2. Multimodality imaging:

   • CT calcium scoring: Severe AS is likely with calcium scores ≥2000 AU for men or ≥1200 AU for women 2
   • Indexed AVA: An indexed AVA ≤0.6 cm²/m² strongly suggests severe AS 1

3. Additional parameters:

   • Evaluate valve morphology and calcification
   • Assess LV global longitudinal strain (often reduced despite normal LVEF)
   • Consider BNP levels (elevated in true severe AS)

Treatment Recommendation

According to the 2021 ESC/EACTS and 2020 ACC/AHA guidelines 1:

1. Intervention is indicated (Class IIa recommendation) for symptomatic patients with low-flow, low-gradient severe AS with preserved LVEF after careful confirmation of stenosis severity 1.

2. TAVR is preferred for this fragile patient with CKD for several reasons:

   • Lower procedural risk compared to surgical AVR
   • Reduced risk of acute kidney injury
   • Better outcomes in frail patients
   • Avoids cardiopulmonary bypass which can worsen kidney function

3. Heart Team approach is essential, involving:

   • Interventional cardiologist
   • Cardiac surgeon
   • Nephrologist
   • Geriatrician (for frailty assessment)

Special Considerations for CKD Patients

Patients with CKD and AS require special attention 3:

1. Pre-procedure optimization:

   • Minimize contrast volume during TAVR
   • Consider pre-procedure hydration (if not contraindicated)
   • Hold nephrotoxic medications

2. Valve choice considerations:

   • Bioprosthetic valves are generally preferred in CKD patients
   • Mechanical valves increase bleeding risk with anticoagulation in CKD
   • Risk of accelerated bioprosthetic valve deterioration exists in CKD

3. Post-procedure care:

   • Close monitoring of kidney function
   • Careful medication adjustment
   • Regular echocardiographic follow-up

Prognosis

Patients with paradoxical low-flow, low-gradient severe AS have worse outcomes compared to high-gradient severe AS 4, but significantly better outcomes with valve replacement compared to medical therapy alone. A recent study showed that patients with paradoxical low-flow, low-gradient AS had similar survival rates after TAVR as those with normal-flow high-gradient AS 5.

Conclusion

This patient should be labeled as having "paradoxical low-flow, low-gradient severe aortic stenosis with preserved LVEF" (HAVEC stage D3). After confirmation of true stenosis severity, TAVR is the recommended intervention given the patient's fragility and CKD. A Heart Team approach with nephrology involvement is essential for optimal outcomes.