What is the management approach for patients with abnormal Proximal Isovelocity Surface Area (PISA) values indicating significant mitral regurgitation?

Management of Abnormal PISA Values in Mitral Regurgitation

The management of patients with abnormal Proximal Isovelocity Surface Area (PISA) values indicating significant mitral regurgitation requires a comprehensive evaluation that integrates multiple parameters rather than relying on PISA measurements alone, as PISA has significant technical limitations that can lead to misclassification of MR severity.

Understanding PISA Limitations

PISA measurements have several important limitations that can affect clinical decision-making:

• Geometric assumptions: PISA assumes a hemispheric flow convergence and circular orifice, which often doesn't apply in secondary MR where the regurgitant orifice is typically crescentic 1
• Timing issues: Single-frame PISA measurements can overestimate MR severity when regurgitation is non-holosystolic (early, late, or biphasic) 1
• Measurement errors: Small differences in radius measurement (e.g., 7mm vs 8mm) can result in significant differences in calculated EROA due to the squared relationship 1
• Multiple jets: PISA may underestimate severity when multiple jets are present 1
• Patient factors: PISA can overestimate MR severity in patients with smaller LV volumes, particularly women 2

Integrated Assessment Approach

Step 1: Confirm MR Severity with Multiple Parameters

• Integrate PISA with other quantitative and qualitative parameters:
  • Effective Regurgitant Orifice Area (EROA)
  • Regurgitant Volume (RVol)
  • Regurgitant Fraction (RF)
  • Vena contracta width
  • Pulmonary vein flow pattern
  • Left atrial and ventricular size
  • Continuous wave Doppler characteristics 1

Step 2: Differentiate Primary vs Secondary MR

• Primary MR: Morphological abnormalities of leaflets/chordae

  • Flail leaflet, leaflet destruction, or perforation are specific markers of severe MR
  • LV/LA dilation typically indicates severe chronic MR 1

• Secondary MR: Normal leaflet morphology with LV/LA abnormalities

  • More challenging to assess as LV/LA dilation may be due to underlying cardiomyopathy
  • Consider using volumetric methods which have shown better prognostic value than PISA in functional MR 3

Step 3: Management Algorithm Based on MR Type

For Primary MR:

1. If symptomatic with moderate-severe/severe MR:

   • Refer for surgical mitral valve repair or replacement 1

2. If asymptomatic with moderate-severe/severe MR:

   • Surgical intervention if:
     • LV EF <60% or LV end-systolic diameter ≥4.0 cm
     • New-onset AF
     • Resting pulmonary artery systolic pressure >50 mmHg
     • Progressive increase in LV size or decrease in EF on serial studies 1
   • Otherwise, close monitoring with periodic echocardiography

For Secondary MR:

1. Optimize guideline-directed medical therapy (GDMT) first

   • MR severity often decreases with optimal heart failure treatment 1
   • Reassess MR after optimization of medical therapy, as MR is dynamic and can improve 1

2. If persistent moderate-severe/severe MR despite optimal GDMT:

   • Consider transcatheter edge-to-edge repair (TEER) if patient meets appropriate criteria 1
   • Surgical options may be considered in selected patients undergoing cardiac surgery for other indications 1

Special Considerations

When to Use Alternative Imaging Methods

• 3D echocardiography: Consider when PISA assumptions are violated (crescentic orifice)
• Cardiac MRI: When echocardiographic findings are inconsistent or equivocal 1
• Volumetric methods: Particularly valuable in secondary MR where they show better prognostic significance than PISA 3

High-Risk Features Requiring Closer Monitoring

• EROA ≥0.4 cm² and RVol ≥60 mL in primary MR 1
• EROA ≥0.2 cm² and RVol ≥30 mL in secondary MR, particularly when confirmed by volumetric methods 3
• Elevated pulmonary artery pressure
• Progressive LV dilation or dysfunction 1

Pitfalls to Avoid

1. Relying solely on PISA for decision-making: Always integrate multiple parameters 1

2. Ignoring the dynamic nature of MR: Assess under stable loading conditions and after medical optimization 1

3. Applying primary MR thresholds to secondary MR: Secondary MR may be significant at lower EROA/RVol values 1

4. Misinterpreting non-holosystolic MR: Recognize that early or late systolic MR can lead to PISA overestimation 1

5. Overlooking patient-specific factors: Consider LV size, gender, and body surface area when interpreting PISA values 2

By following this structured approach and understanding the limitations of PISA measurements, clinicians can more accurately assess MR severity and make appropriate management decisions that improve outcomes for patients with mitral regurgitation.