Mitral regurgitation
Mechanism first (primary, ventricular or atrial secondary), integrated severity, then LV and LA triggers.
Numbers to remember
- Severe primary MR: VC ≥7 mm, EROA ≥0.40 cm², RVol ≥60 mL, RF ≥50% [4,34]
- Asymptomatic severe primary MR → surgery if LVEF ≤60% or LVESD ≥40 mm [6,7]
- Also consider repair for new AF, PASP >50 mmHg, or marked LA dilatation [6]
- EROA ≥0.40 cm² → about 58% 5-year survival in asymptomatic degenerative MR [59]
Questions echo must answer
MR is two diseases. Primary MR is a disease of the leaflets or chords, and repair cures it. Secondary MR is a disease of the ventricle or atrium, and treating the chamber comes first [4,6]. Echo must name the mechanism, quantify, and measure the LV and LA consequences that time surgery [6,7].
- MechanismCarpentier class I (normal motion: perforation, cleft, annular dilatation), II (excessive motion: prolapse or flail), IIIa (rheumatic restriction), IIIb (systolic tethering) [4].
- Primary or secondary?Ventricular versus atrial functional MR [6].
- SeverityVC, PISA EROA and RVol, CW density, pulmonary vein flow, E velocity [4].
- ConsequencesLVEF, LVESD, LA volume, PASP, AF [6,7].
- RepairabilityLocation (P2 flail is simplest), calcification, leaflet length; TOE and 3D when surgery is planned [35].
Acquisition protocol
- PLAX / PSAX-MV / apical viewsIdentify the scallop involved (A1–A3, P1–P3); flail versus prolapse; annular calcification.
- Colour zoomVena contracta in a view perpendicular to the coaptation line (PLAX), with a narrow sector and high frame rate [4].
- PISAShift the baseline towards the jet direction (Nyquist 30–40 cm/s). Measure the radius in mid-systole. EROA = 2πr² × Va / Vmax(MR); RVol = EROA × VTI-MR [4].
- CWDensity and shape (triangular, early peak = high LA pressure); timing (holosystolic versus late-systolic) [4].
- PWMitral E velocity; pulmonary vein flow (systolic blunting or reversal) [4].
- VolumetricRVol = mitral SV − LVOT SV (check).
- LV / LALVESD, volumes, LVEF, GLS; LAVI; PASP [6,7].
- ExerciseSymptoms discordant with severity: exercise echo for PASP (exercise PH) and change in EROA [28,189].
- Mechanism and scallop
- VC
- PISA EROA and RVol
- CW density and timing
- Pulmonary vein flow
- LVEF, LVESD
- LAVI, rhythm
- PASP
- Grade (integrated)
Diagnosis & severity
| Parameter | Mild | Moderate | Severe |
|---|---|---|---|
| Vena contracta (mm) | <3 | 3–6.9 | ≥7 |
| EROA (cm²) | <0.20 | 0.20–0.39 | ≥0.40 |
| RVol (mL) | <30 | 30–59 | ≥60 |
| RF (%) | <30 | 30–49 | ≥50 |
| CW jet | Faint, parabolic | Dense | Dense, triangular |
| Pulmonary vein | Systolic dominance | Blunted | Systolic reversal |
| Mitral E | A-wave dominant | Variable | >1.2 m/s |
Sources: ASE 2017, EACVI [4,34].
NoteIn secondary MR, the orifice is elliptical and PISA underestimates it. A lower EROA may already be haemodynamically significant. Proportionality to LV volume (EROA ÷ LVEDV) explains why COAPT benefited and MITRA-FR did not [4,185,186].
Thresholds that change management
- Symptomatic severe primary MR → surgery (repair preferred). TEER if surgical risk is high and the anatomy is suitable [6,7].
- Asymptomatic severe primary MR → surgery if LVEF ≤60% or LVESD ≥40 mm. Consider early repair at a heart valve centre with new AF, PASP >50 mmHg at rest, or significant LA dilatation, if durable repair is likely [6,7].
- Flail leaflet with LVEF <60% or LVESD ≥40 mm carries higher long-term mortality even after surgery [92].
- Exercise PASP ≥60 mmHg in asymptomatic degenerative MR predicted earlier symptoms [189].
- Secondary MR → GDMT, CRT and revascularisation first; then TEER if still severe and in the COAPT profile [64,185].
- Atrial functional MR → rhythm control and treat the atrium and annulus [6,182].
Pitfalls & mimics
PitfallLate-systolic MR (mitral valve prolapse) looks severe on a single-frame PISA. Calculate RVol with the MR VTI, which captures its short duration [4].
- Eccentric wall-hugging jets (Coanda effect) look small on colour area. Use VC and PISA.
- Colour gain, Nyquist limit and a wide sector all change the jet area. Do not grade by colour area alone.
- Hypertension during the study increases MR. Note the BP.
- Multiple jets make PISA and VC not additive. Use volumetric methods or 3D VCA.
- MAC makes E velocity and E/e′ unreliable.