How do you manage a patient with paradoxical severe aortic stenosis?

Management of Paradoxical Severe Aortic Stenosis

For symptomatic patients with paradoxical low-flow, low-gradient severe AS (preserved LVEF, AVA ≤1.0 cm², mean gradient <40 mmHg, stroke volume index <35 mL/m²), aortic valve replacement is recommended after careful confirmation that the stenosis is truly severe, with ACC/AHA providing a Class 1 recommendation and ESC/EACTS a Class IIa recommendation. 1

Confirming True Severe AS vs. Pseudo-Severe AS

The critical first step is distinguishing true-severe from pseudo-severe AS, as approximately 60% of patients with paradoxical low-flow, low-gradient AS have genuinely severe disease warranting intervention 2:

Initial Assessment

• Rule out measurement errors in echocardiographic parameters, particularly ensuring accurate AVA calculation and gradient measurements 2
• Aggressively treat hypertension, as elevated afterload can artificially reduce stroke volume and create the appearance of low-flow state 2

Multimodality Imaging for Confirmation

Aortic valve calcium scoring by cardiac CT is the preferred modality for confirming severity in paradoxical low-flow, low-gradient AS 1, 3:

• Men: calcium score ≥2000 Agatston units indicates true-severe AS 2
• Women: calcium score ≥1200 Agatston units indicates true-severe AS 2
• This approach is superior to traditional criteria and should be used when stress echocardiography is not feasible or inconclusive 2, 3

Dobutamine stress echocardiography is less useful in paradoxical AS (reserved for classical low-flow, low-gradient AS with reduced LVEF) but can calculate projected AVA if performed 2, 3

Intervention Decision Algorithm

Symptomatic Patients with Confirmed Severe AS

Proceed with aortic valve replacement once AS severity is confirmed 1:

• ACC/AHA gives Class 1 recommendation when AS is the most likely cause of symptoms, particularly with severely calcified valve and AVA ≤1.0 cm² 1
• ESC/EACTS gives Class IIa recommendation after comprehensive evaluation confirms significant valve obstruction 1

Symptom assessment must be objective, not relying solely on patient-reported symptoms:

• Perform formal exercise testing to objectively document exercise limitation 2
• Many patients unconsciously reduce activity levels and underreport symptoms 2

Asymptomatic Patients with Confirmed Severe AS

Close surveillance is generally recommended, but consider early intervention (Class IIb) if high-risk features are present 1:

High-risk markers warranting consideration of early AVR:

• Markedly reduced stroke volume index (<35 mL/m²) 2
• Myocardial fibrosis on cardiac MRI indicating advanced LV remodeling 1, 2
• Reduced global longitudinal strain by speckle tracking echocardiography 1, 2
• Moderate-to-severe LV diastolic dysfunction 2
• High calcium score (>2000 AU in men, >1200 AU in women) 1, 2

Mode of Intervention

TAVR vs. SAVR Selection

Both TAVR and SAVR are viable options, with choice depending on surgical risk and anatomic factors 1:

TAVR advantages in paradoxical AS:

• Lower risk of severe patient-prosthesis mismatch, which is particularly important given the small, non-compliant LV cavity typical in these patients 2
• Demonstrated hemodynamic benefits with increased post-TAVR valvular flow 1
• Superior to medical management in inoperable patients 2

TAVR considerations:

• Higher risk of paravalvular regurgitation, which may be poorly tolerated by patients with small, stiff LV cavities 2
• Some registry data suggest acceptable outcomes in paradoxical AS, though direct SAVR comparison groups are limited 1

SAVR remains appropriate for low-risk patients with favorable anatomy 1

Prognostic Context

Paradoxical low-flow, low-gradient AS with preserved LVEF carries worse prognosis than high-gradient AS:

• Associated with significantly higher 5-year all-cause mortality compared to moderate or high-flow AS 1
• However, intervention improves survival in patients with confirmed true-severe AS 1
• Decision-making must account for comorbidities, degree of valve calcification, extent of CAD, and feasibility of revascularization 1

Common Pitfalls to Avoid

• Do not rely on AVA alone without confirming with calcium scoring or other modalities, as pseudo-severe AS is common 2, 3
• Do not accept patient-reported "asymptomatic" status without objective exercise testing 2
• Do not delay intervention in symptomatic patients with confirmed severe AS, as outcomes worsen with medical management 1
• Do not use dobutamine stress echo as first-line confirmation tool in paradoxical AS (it's for classical low-flow, low-gradient with reduced EF) 2, 3