Mitral Regurgitation

Acute MR

• Common causes include:
  • Endocarditis
  • Papillary muscle rupture or chordal muscle rupture, e.g. after recent MI or infarction
    • Can result in flail leaflet
• Sudden ↑ in LA and LV volume in the absence of compensatory LV or atrial dilation.
• Management
  • Urgent surgery

Post-MI Mitral Regurgitation

Papillary muscle rupture

• Complicates 1-5% of acute Medications
• Usually 2-7 days after the acute ischemic event; typically first MI
• Posteromedial papillary muscle more commonly ruptured (10x more likely) due to have single blood supply (posterior descending artery)
  • The anterolateral papillary muscle has dual blood supply
• ⚠️ Exam may not have feature a hyperdynamic precordium or audible murmur
  • d/t rapid and complete equalization of pressure between the LV and LA.
  • By contrast, ventricular septal rupture would present similarly, but you’ll hear a loud murmur.

Ischemic Mitral Regurgitation

Chronic Mitral Regurgitation

• “If you see MR, you need to ask why?”
  • “A comprehensive evaluation of valvular regurgitation should include identifying the mechanism and the severity of valvular regurgitation, along with adaptation of the heart to the volume overload.”

• Results in LV volume overload → ventricular (and atrial) remodeling w/ eccentric hypertrophy, i.e. LV dilation w/o increased wall thickness.
• Can be tolerated for several years. Only after several years (typically), may it lead to ↓ contractility and systolic dysfunction → ↑ pulmonary venous pressure, ↓ SV and ↓ CO.
  • ↑ LAP: pulmonary congestion, pulmonary hypertension, and atrial fibrillation

4, 5, 6, 7 of Severe MR

EROA ≥ 0.4 cm2 Regurgitant fraction ≥ 50% Regurgitant volume ≥ 60 mL Vena contracta ≥ 0.7 cm

Source: Figure 18 of 2017 ASE Valvular Guidelines

• Primary or Secondary (functional) MR?
  • differentiates 1˚ lesions of the mitral leaflets and subvalvular apparatus from 2˚ dysfunction d/t annular or LV dilatation/remodeling and/or dysfunction.
• Most common causes of MR: Secondary MR is the most prevalent form of MR, followed by Mitral Valve Prolapse (MVP), ischemic MR.
• Primary MR includes:
  • myxomatous ∆, notably Mitral Valve Prolapse (MVP)
  • Mitral Annular Calcification (MAC)
  • Rheumatic Heart Disease
  • Connective Tissue Disease
  • radiation therapy ☢️
  • adverse effects of medications 💊

Carpentier Classification ![[Mitral Regurgitation-20240909204253253.webp]] [Figure source](https://www.ahajournals.org/doi/full/10.1161/CIRCINTERVENTIONS.120.008998)

• Echo
  • Don’t forget to provide information regarding the associated conditions or sequelae of MR, such as pulmonary hypertension, tricuspid regurgitation, LA dilation, and ventricular dilation or systolic dysfunction
  • ⚠️ In the presence of severe primary or secondary MR, use of LVEF may overestimate systolic function because of the lower impedance of the LA chamber.
    • Be sure to check LVESD
  • TEE can also be helpful given its ↑ spatial resolution and the proximity of the probe to the MV.
    • MV surgical views are 🔥
  • Echo Doppler
    • vena contracta width, ERO, spatial distribution of MR jet w/in the LA, flow convergence
• Screening
  • After the initial echocardiographic evaluation, repeat echocardiography is indicated for patients with moderate or greater MR, even in the absence of symptoms
  • Frequency
    • Severe MR: every 6-12 months
    • Moderate MR: every 1-2 years
    • Mild MR: every 3-5 years
    • ⚠️ Repeat echocardiography is also recommended for patients with any degree of MR and a change in clinical status or physical examination findings.

Primary Mitral Regurgitation

“Primary MR is a fancy way for saying prolapse.”

- David Skolnick, August 9, 2024

Common Causes of Chronic Primary MR

Etiology	Affected Valve Level(s)
Degenerative (see MVP)	leaflets, chordae, annulus
Mitral Annular Calcification (MAC)	annulus, leaflets
CAD → ruptured papillary mm.	papillary mm.
Rheumatic Heart Disease	leaflets, chordae
Endocarditis	leaflets, chordae
Hypertrophic Cardiomyopathy	leaflets, chordae, papillary mm.
Connective Tissue Dz (RA, SLE, APLS)	leaflets, annulus
Radiation ☢️	leaflets, chordae
Drugs (ergotamines, methysergide, pergolide, fenfen, dexfen)	leaflets, chordae

• “A mechanical problem requires a mechanical solution”
  • Primary MR is a mechanical problem of the leaflet coaptation that only has a mechanical solution, i.e. MV intervention

Secondary Mitral Regurgitation

• Secondary MR occurs in approximately 65% of cases reported with left ventricular dysfunction or remodeling as the predominant cause.