What is the assessment and management approach for a patient with suspected prosthetic mismatch?

Assessment and Management of Prosthetic Valve Mismatch

Patient-prosthesis mismatch (PPM) should be suspected in any patient with persistent cardiac symptoms after aortic valve replacement who has high prosthetic valve velocity or gradient (mean gradient >20 mmHg) with a small calculated indexed effective orifice area (iEOA ≤0.85 cm²/m²), after excluding other causes of increased transvalvular gradient. 1

Definition and Diagnostic Criteria

PPM occurs when the effective orifice area of a normally functioning prosthetic valve is too small relative to the patient's body size and metabolic demands. 1

Severity Classification:

• Moderate PPM: iEOA 0.65-0.85 cm²/m² 1
• Severe PPM: iEOA <0.65 cm²/m² 1

Clinical Assessment Algorithm

Step 1: Initial Evaluation

When a patient fails to improve or deteriorates after valve replacement, perform comprehensive testing: 1

• Transthoracic echocardiography (TTE) with 2D and Doppler assessment 1
• Measure peak velocity, mean gradient, and calculate effective orifice area by continuity equation 1
• Assess left ventricular function, hypertrophy regression, and other valve disease 1
• Transesophageal echocardiography (TEE) if TTE is inadequate or results are discordant 1

Step 2: Distinguish PPM from Prosthetic Valve Stenosis

Critical distinction: PPM shows high gradients with normal leaflet morphology and mobility, while prosthetic stenosis shows abnormal leaflet structure or motion. 1

Key differentiating features of PPM: 2

• High transprosthetic velocity and gradients
• Normal calculated effective orifice area for that specific prosthesis model
• Small indexed effective orifice area (<0.85 cm²/m²)
• Normal leaflet morphology and mobility on imaging
• Stable measurements over time (not progressive)

Use TEE or CT to assess leaflet morphology and mobility - this is the cornerstone of differential diagnosis. 1, 2

Step 3: Exclude Other Causes of High Gradients

Before attributing symptoms to PPM, rule out: 1

• Prosthetic valve thrombosis (consider if inadequate anticoagulation history, acute onset) 1
• Structural valve degeneration 1
• Prosthetic valve endocarditis 1
• Paravalvular leak or dehiscence 1
• Progression of other valve disease 1
• Coronary artery disease 1

Important caveat: With bileaflet mechanical valves, significant pressure recovery may result in high velocity that should not be mistaken for PPM, particularly in patients with small aortic diameters. 1

Clinical Impact Assessment

Severe PPM is especially detrimental in patients with reduced left ventricular ejection fraction and may decrease the likelihood of symptom resolution and LVEF improvement. 1

PPM is associated with: 1

• High transvalvular gradients
• Persistent left ventricular hypertrophy
• Increased rate of cardiac events

Management Approach

Medical Management

Patients with postoperative LV systolic dysfunction should receive standard medical therapy for systolic heart failure, continued indefinitely even if systolic function improves. 1

Surgical Intervention Considerations

Repeat valve replacement is indicated for severe symptomatic prosthetic valve stenosis. 1 However, for PPM specifically:

Re-intervention should only be considered if: 1

• Symptoms persist despite optimal medical therapy
• Severe PPM (iEOA <0.65 cm²/m²) is confirmed
• Patient has reduced LVEF or significant functional limitation
• Expected benefits justify the surgical risk

The only effective intervention is redo surgery with implantation of a larger valve and/or annular enlargement. 3

Decision requires careful hemodynamic evaluation based on: 1

• Hemodynamic abnormalities
• Symptom severity
• Ventricular function
• Surgical risk assessment

Alternative Options for Bioprosthetic Valves

For severely symptomatic patients with bioprosthetic aortic valve stenosis at high or prohibitive surgical risk, transcatheter valve-in-valve procedure with fracturing of the surgical valve stent may be considered. 1, 2

Prevention Strategy (For Future Reference)

PPM can be largely prevented by prospective planning at the time of initial valve replacement: 1

• Calculate predicted iEOA using the normal reference EOA of the selected prosthesis and patient's body surface area
• Choose valve prosthesis that will provide adequate iEOA (>0.85 cm²/m²)
• Consider annular enlargement procedures if needed
• Consider transcatheter AVR over surgical AVR in patients with small (<21 mm) aortic annulus 4, 2