2. Definition
• Mitral regurgitation (MR) is a systolic retrograde flow from the LV to
the left atrium (LA) because of the lack of adequate coaptation of the
leaflets.
• Ischaemic mitral regurgitation (MR) is defined as MR caused by
changes of left ventricular structure and function related ultimately to
ischaemia.
• The term ischaemic MR is usually related to chronic MR, occurring >2
weeks after infarction and in the absence of structural mitral valve
disease
Marwick, T. H., Lancellotti, P., & Pierard, L. (2009). Ischaemic mitral regurgitation: mechanisms
and diagnosis. Heart, 95(20), 1711–1718. doi:10.1136/hrt.2007.135335
3. • Primary MR- is an organic disease of one
or more components of the mitral valve
apparatus namely
Annulus
Leaflets
Chordae
Papillary muscles
• Secondary MR- is not a valve disease, but
represents the valvular consequences of
a LV disease.
4. • In Functional MR valve leaflets and chordae are structurally normal
and MR is secondary to alterations in the left ventricle (LV) geometry.
• Idiopathic cardiomyopathy/ Ischaemic cardiomyopathy
• Secondary functional MR in the setting of ischaemic cardiomyopathy
is known as ischaemic MR
5. Mitral leaflet adaptation in chronic MI
• Structural changes occurs in leaflets
• Adaptation is leaflet enlargement
• Stiffness increased due to profibrotic changes
• The development of significant MR is associated with insufficient
leaflet area relative to that demanded by tethering geometry
Circulation: Cardiovascular Imaging. 2018; editorial- based on the study by Nishino etal. Mitral
Valve Adaptation Can We Win the Race? Dae-Hee Kim, MD, PhD Jacob P. Dal-Bianco, MD Elena
Aikawa, MD, PhD Joyce Bischoff, PhD Robert A. Levine, MD
6. Carpentier classification of IMR
• Most common carpentier class in IMR is Type III b dysfunction
- Restricted leaflet tip motion in systole
• Type I- normal leaflet motion
annular dilatation
• Type II- excess motion
Acute MI
- chordae rupture
Chronic MI
- PM contractile dysfunction
7. Consequences of LV disease
Tethering & Tenting
• Dilatation and Remodeling of LV
• Annular dilatation predominantly in
the septo-lateral direction.
• Less in IMR than degenerative MR or dilated
cardiomyopathy
• Apical, posterior & lateral displacement of papillary
muscles
• Increased traction on mitral leaflets- Tethering
• Produces a tent shaped area between annular plane
and leaflets- Tenting
8. Mechanism of Ishaemic MR
Valvular consequence of the imbalance between
tethering and closing forces acting over valve
leaflets
increased tethering forces
reduced closing forces
loss of dynamic balance
9. Determinants of the degree of functional mitral
regurgitation
• Leaflet tethering & tenting
• causes displacement of coaptation point
from annulus towards apex
• along with loss of systolic annular
contraction
• altogether creating an incomplete systolic
valve coaptation
Yiu SF, Enriquez-Sarano M,Tribouilloy C, et al.
Determinants of the degree of functional mitral
regurgitation in patients with systolic left ventricular
dysfunction with 2D echo: a quantitative clinical study.
Circulation 2000
10. Tenting volume and Area
• Quantification and classification
• 3-Dimensional tenting volume correlates well with EROA
Watanabe N, Ogasawara Y, Yamaura Y, Kawamoto T, Toyota E, Akasaka T, Yoshida K. Quantitation
of mitral valve tenting in ischemic mitral regurgitation by transthoracic real-time three-
dimensional echocardiography. JACC 2005;45:763– 769.
11. PM dysfunction & dyssynchrony
• Usually seen with Posterior & transmural infarction
• PM will show contractile dysfunction
• In LBBB, mechanical activation occurs first in the segment adjacent to the
posterior papillary muscle and is delayed in the segment with the
anterolateral papillary muscle insertion causing dyssynchrony.
• With cardiac resynchronisation therapy , the interpapillary muscle activation
time delay is shortened and this causes significant decrease in mitral
regurgitant fraction
12. Paradox- PM dysfunction decreases IMR
• PM contraction increases apical
tethering & IMR
• Papillary muscle contractile
dysfunction occurs
• Tethering is decreased, which inturn
improves coaptation.
Messas E, Guerrero JL, Handschumacher MD, Chow
CM, Sullivan J, Schwammenthal E, Levine AR. Paradoxic
decrease in ischemic mitral regurgitation with papillary
muscle dysfunction: insights from three-dimensional
and contrast echocardiography with strain rate
measurement. Circulation 2001;104:1952–1957
13. Role of Annular configuration in IMR
• IMR patients presents with dilated and flattened annulus
• Loss of saddle configuration is more evident with Anterior MI
• Isolated annulus dilation does not lead to mitral regurgitation
because normal leaflet area is more than double the annular area
resulting in an adequate reserve.
• if the annulus dilation is combined with the leaflet tethering, they
both contribute to FMR
Watanabe N, Ogasawara Y, Yamaura Y, Kawamoto T, Toyota E, Akasaka T, Yoshida K. Quantitation
of mitral valve tenting in ischemic mitral regurgitation by transthoracic real-time three-
dimensional echocardiography. JACC 2005;45:763– 769
14. Mechanism contd….
• Reduction in closing forces occurs due
to
decreased LV contractility
altered systolic annular contraction
PM & mechanical LV dyssynchrony
15. LV dyssynchrony
i. Decreased LV contraction efficiency and the decreased closing
forces- most important mechanism
ii. Uncordinated regional LV mechanical activation in segments
supporting papillary muscles which increases mitral leaflet
tethering
iii. A positive pressure gradient which develops between LA & LV due
to improper timing of AV relaxation and contraction cycles
Ischemic mitral regurgitation: mechanisms and echocardiographic classification. Eustachio
Agricola*, Michele Oppizzi1, Matteo Pisani, Alessandra Meris, Francesco Maisano and Alberto
Margonato. European Journal of Echocardiography (2008)9,207-
221doi:10.1016/j.euje.2007.03.034
16. Asymmetric & symmetric IMR
Posterior infarction reduces mobility of PML close to medial
commissure causing AML override
• Hence tenting area as well as the jet will be assymetric
Large anterior or multiple infarcts
• LV dilatation is more global
• Causes bileaflet apical tethering
• Shift of leaflet coaptation into ventricle
• Symmetric tenting area/ central jet
17. Classification
• Symmetric & Asymmetric tethering pattern
• Acute IMR-
Rupture of a papillary muscle
Secondary to a transient active ischaemic episode.
• Sudden-onset LV dysfunction in AMI may cause loss of MV coaptation
even with a relatively mild degree of valve tethering
• Chronic IMR left ventricular geometry will be disturbed secondary to
myocardial ischemia.
19. Left atrial remodeling cause or consequence?
• Ischemic MR progression affects atrial structural remodeling
• Due to LA volume & pressure overload
• In an animal study, acute atrial dilation and dysfunction due to LA
infarction has contributed to the early occurrence of ischemic MR
Aguero J, Galan-Arriola C, Fernandez-Jimenez R, Sanchez-Gonzalez J, Ajmone N, Delgado V, Solis J,
Lopez GJ, de Molina-Iracheta A, Hajjar RJ, Bax JJ, Fuster V, Ibanez B. Atrial infarction and ischemic
mitral regurgitation contribute to post-MI remodeling of the left atrium. JACC. 2017;70:2878–
2889. doi: 10.1016/jacc.2017.10.013.
20. Dynamic aspect of IMR
• Anaesthetic induction can substantially reduce MR, confounding
decisions regarding repair.
• Example for this dynamic behavior is a vanishing MR during intra-op
TEE.
• EROA is determined by changes in trans-mitral pressure & loading
conditions
• Phenylephrine can restore the driving pressures.
• Intravenous volume loading can be done to titrate mean blood
pressure ≥90 mm Hg, and wedge pressure of around 12 mm Hg
21. A clinical puzzle- patients with exertional dyspnea out of
proportion to their resting MR
• Dynamism aspect of IMR seen during exercise
• EROA/ RV changes during exercise
• 30% patients have an increase in EROA by >20 mm2 (enough to
change clinical grade)
• Decrease in EROA noticed only in patients
with recruitable LV contractile reserve
reduction in LV dyssynchrony & reverse remodeling due to Rx
• Exercise can unmask the severity of what might otherwise be
considered a mild MR.
Even though IMR is a secondary functional one, based on the study of Nishino etal, editorial of circulation cardiovascular imaging 2018 mentions that there is an evidence of MV leaflet adaptation in IMR
Carpentier’s classification applied to IMR.
What are the consequences of LV disease? Often come across 2 terms T & T. Post MI there will be dilatation and remodeling. Remodeling can be global or regional
Tethering force pulls the leaflets towards apex and closing forces push the leaflets away from apex
A clinical study published in circulation, found that 2 main determinants of IMR are tethering and tenting which are the consequences of LV ischemia
Another important aspect of tenting is its volume and area
One of the main contributors to the mechanism of IMR is PM dysfunction and dyssynchrony
PM contraction increases apical tethering and IMR
Change in annular configuration is a contributory factor in the mechanism of FMR
Mechanisms causing reduction in closing forces are
LV synchrony can contribute to IMR by 3 mechanisms
There are 2 phenotypes of IMR
The more the MR, the more the volume overload which causes
An animal study published in JACC 2017 found a close association between LA infaction and IMR