Ischemic Mitral Regurgitation

1. Surgical Treatment of Ischemic Mitral
Regurgitation
Nora Albogami
PGY-3

2. Contents:
Introduction
Anatomy and physiology
Medical therapies
Revascularization
Addressing the Mitral Valve
a) Current evidence
b) Advances in surgical techniques
c) Valvular techniques
d) Subvalvular techniques
e) Surgical and external ventricular remodeling

3. Ischemic mitral valve regurgitation (IMR) occurs as 2 related but distinct complications of myocardial
infarction.
1. Acute IMR. results from acute papillary muscle rupture following a myocardial infarction.
Patients with acute IMR usually present in extremis and often require urgent surgical
intervention with increased perioperative risk.
2. Conversely, chronic IMR (cIMR), is a result of ventricular remodeling following myocardial
infarction and has a more indolent progression.

4. • Chronic IMR occurs in approximately 25% of patients status after myocardial infarction and in up
to half of patients after myocardial infarction with left ventricular dysfunction and heart
failure.
• It is associated with poor outcomes that worsen in direct correlation to the severity of valvular
insufficiency, with even mild cIMR resulting in significantly worse outcomes than similar
ischemia without cIMR.
• As the population ages and the incidence of coronary artery disease increases, the number of
patients with cIMR will only continue to grow.

5. Anatomy
Annulus
Leaflets
Subvalvular
Apparatus

6. • The anterior papillary muscle
most often has a type I configuration with occasionally an adjacent
type III papillary muscle attaching the commissural chordae.
• The posterior papillary muscle
usually has a type II configuration with one head attaching the chordae
of the anterior leaflet, one head attaching the commissural chordae,
and one head attaching chordae of the posterior leaflet.

7. Mitral leaflet perfusion:
• Mitral valves are traditionally thought to be
avascular, and recent publications have proposed
that the presence of blood vessels in the valves is
pathologic.
• In 1852, Luschka first reported findings that
demonstrated the presence of blood vessels
within the leaflets of normal human heart valves.
• Luschka identified a network of vessels in the
broad portion of the human mitral valve, with
small vessels running to the line of coaptation
and a few vessels in the chordae tendineae

8. Based on previous dye and histologic studies that have shown vessels in the chordae
tendineae in multiple species (including humans), it is likely that the AML inflow via
chordal vessels.

9. Carpentier classification of mitral valve regurgitation

10. Anatomy and Physiology
• MI causes negative ventricular remodeling and alterations in valve-ventricle interactions.
• Chronic IMR results from a combination of loco-regional changes in ventricular anatomy includin:
1. Annular dilatation (carpentier class I mitral regurgitation)
2. Leaflet tethering in systole (class iiib)
3. Global left ventricular hypokinesis.
 Although each pathologic derangement is usually present in cIMR, the relative contribution of each
is variable.

11. • In cIMR has a more pronounced
derangement of the annulus in the P2-P3
region resulting from infarction of the
posterior wall of the ventricle.
• The Apical and posterior displacement of
the papillary muscles toward the infarct zone
causes negative ventricular remodeling
results in worsening left ventricular
dilatation, the tethering becomes more
complex.
• The end result is that the interpapillary
muscle distance increases and the
individual tips of the papillary muscles move
away from the coaptation zone, preventing
the leaflets from reaching the annular
plane and coapting in systole

12. • The associated left ventricular and papillary muscle dyssynchrony results in worsened dynamic leaflet
tethering and cIMR.
• The vast majority of cIMR is caused by posterior left ventricular infarction, resulting in asymmetric
dilation of the left ventricle (LV) with apical and posterior displacement of the posteromedial
papillary muscle.
• Chronic IMR is further worsened by the resultant asymmetric dilatation of the P2-P3 portion of the
posterior mitral annulus.
• This is in contrast to the symmetric dilatation seen in nonischemic dilated cardiomyopathy where
apical tethering may be more pronounced but mitral regurgitation is less common.

13. • The regurgitant jet in cIMR is usually central as it results from leaflet tethering
and not abnormal leaflet motion; however, the asymmetric P2-P3 dilatation and
posterior tethering may sometimes lead to “pseudo-prolapse” of the anterior leaflet in
which more pronounced tethering of the posterior leaflet results in an overriding
anterior leaflet and a posteriorly directed jet.

14. Medical Therapies
• The only class I, level A recommendations for the management of cIMR are related to medical
management.
1. Patients with cIMR with heart failure and reduced ejection fraction should receive standard medical
therapy for heart disease as indicated, including ACE inhibitors, angiotensin- receptor blockers, beta-
blockers, and aldosterone antagonists.
 In a randomized, double-blind, placebo- controlled trial of patients in NYHA class II-III heart failure,
reduced left ventricular ejection fraction, and moderate or worse cIMR
 patients were randomized to captopril or placebo.
 The patents receiving the ACE inhibitor at higher doses had improvements in mitral regurgitation, stroke
volume, systemic vascular resistance, left atrial size, left ventricular size, although survival data are
lacking.

15. 1. Cardiac resynchronization with biventricular pacing for symptomatic patients with cIMR who meet
criteria for resynchronization.
 Cardiac resynchronization has been shown to improve both left ventricular systolic and diastolic function and
decrease mitral regurgitation in patients undergoing optimal medical management.

16. Benjamin H. Trichon. Circulation. Survival After Coronary Revascularization, With and Without Mitral Valve Surgery, in Patients With Ischemic Mitral Regurgitation,
Volume: 108, Issue: 10_suppl_1, Pages: II-103-II-110, DOI: (10.1161/01.cir.0000087656.10829.df)
• Coronary revascularization, including both PCI and
coronary artery bypass grafting (CABG), has been
shown to be superior to medical therapy alone
in patients with cIMR.
Revascularization

17.  In a study by Trichon and colleagues, patients with moderate or greater cIMR had worse long-term
outcomes with medical management alone compared with PCI or CABG with or without mitral valve
intervention.
 Five-year survival was approximately 60% in patients with intervention compared with 41% in patients
with medical management only.

18. • The outcomes of patients with cIMR following myocardial revascularization remain
poor, and revascularization alone often does not reduce the amount of moderate to
severe IMR.
 In the study by Trichon and colleagues, they compared patients who underwent mitral valve intervention
with those who did not, showed a trend toward improved survival with mitral valve intervention
despite higher mean preoperative NYHA functional class and more severe mitral regurgitation

19. which is better preoperative TEE or intraoperative TEE in
evaluating cIMR?
The decision to address the mitral valve must be made based on preoperative data as
intraoperative transesophageal echocardiography (TEE) performed under GA can be
misleading in regard to the severity of mitral regurgitation.
One report demonstrated that 90% of preoperatively determined 3+ mitral regurgitation
was downgraded by intraoperative TEE.
The amount of downgrading by intraoperative TEE has no bearing on the amount of
residual MR following repair and cannot be used as a marker of technical success with
mitral repair.

20. The Historical Approach
• Although there is a clear benefit to mitral valve repair over replacement in degenerative mitral
valve regurgitation in most patient cohorts, the choice is less clear in cIMR.
• Mitral valve replacement was the initial procedure of choice for treating cIMR; however, results were
suboptimal, possibly due to the lack of the subvalvular-sparing techniques.
• As such, the standard of care for many years for patients with cIMR requiring revascularization
became CABG plus mitral valve repair with reduction annuloplasty.
• High recurrence rates after mitral valve repair,
 6-month recurrence rates as high as 33%
 5-year recurrence rates greater than 70%

21. • The theoretical benefits of mitral valve repair over replacement include lower operative morbidity
and mortality, fewer thromboembolic complications, less structural valve deterioration, and better
improvements in left ventricular remodeling and function however the heterogeneity in these cohorts
of patients with cIMR was not fully addressed in these studies.
• Adding mitral valve repair to CABG does not significantly increase perioperative risk.
• The operative mortality for CABG alone in patients with concomitant cIMR has ranged from 0% to
12%, with lower mortality series tending to have fewer emergent operations and less severe mitral
regurgitation.

22. Repair vs Replacemnent
• Operative mortality for CABG + mitral valve repair in larger studies ranges from 1.6% to
12%, with the most recent studies having lower perioperative mortality, and the
determinants of operative risk more related to patient comorbidities than to the addition
of mitral valve repair.
 Glower and colleagues compared patients with cIMR undergoing CABG to patients who did not have cIMR,
and found an operative mortality of 4.3% vs 1.3% (P< 0.01), but analysis showed that only the number
of comorbidities predicted increased operative mortality, not the presence of cIMR.
 Additionally, operative risk is relatively low, compared with CABG + mitral valve replacement, which can
carry an operative mortality ranging from 4% to 45%.
 In MVR:
1. Endocarditis 2 to 3 times more likely with bioprosthetic valves than with valve repair
2. A risk of paravalvular leak and structural valve deterioration.

23. Repair vs Replacemnent
• Following the landmark study by Bolling and colleagues :
• Reduction annuloplasty for the treatment of cIMR, improved the perioperative risk; however, with
the introduction of chordal-sparing mitral valve replacement, the long-term outcomes following
MVR improved as well.
With the risk of functional mitral stenosis and the suboptimal long-term recurrence rates and
survival following mitral valve repair for cIMR, the ideal choice of mitral valve intervention
remains unclear.

24. Repair vs Replacemnent
• retrospective analysis of prospectively collected data by Magne and colleagues, 370 patients with
cIMR underwent mitral valve repair or replacement for cIMR between 1995 and 2008.
• Although hospital mortality was greater with mitral replacement than mitral repair (17.4% vs 9.7%,
P=0.03), there was no significant difference in short- or long-term survival after correction for
baseline characteristics using multivariable analyses and propensity scoring.

25. Current Evidence: Severe ischemic mitral regurgitation

26. • Although some more recent retrospective studies have shown no significant differences in survival
between mitral valve repair and mitral valve replacement for cIMR, others have shown a survival
benefit with mitral valve repair.
A. Lorusso and colleagues reported the results of a 15-year, multicenter analysis of 244
propensity matched pairs of patients with cIMR with left ventricular ejection fraction less
than 40% undergoing complete revascularization with CABG plus either mitral repair
(70.4%) or replacement.
1. They found no difference in perioperative mortality (3.3% vs 5.3%,P=0.32),
2. No difference in survival at 5 or 8 years (85% vs 86%, and 82% vs 80%, respectively), and no difference
in left ventricular ejection fraction or NYHA functional class at follow-up.
3. Mitral valve recurrence (mild to moderate or worse) was higher in the repair group (25% vs 6%) as were
valve- related reoperations (46% vs 31%, P=0.01).

27. • De Bonis and colleagues performed a retrospective analysis of 132 patients with moderate or severe
functional mitral regurgitation, of which two-thirds were ischemic in etiology and only half of whom
received revascularization.
• Approximately two-thirds underwent mitral valve repair with reduction ring annuloplasty with or without
edge-to-edge repair (~25%) and one-third underwent complete chordal-sparing mitral valve replacement.
1. They found that both hospital mortality (2.3% vs 12.7%, P=0.03) and 2.5-year actuarial survival (92% vs 73%,
P=0.02) were better with mitral valve repair.
2. The repair group had significant improvements in left ventricular ejection fraction and ventricular volumes and
trended toward improvement in NYHA functional class
3. Recurrence was higher in the repair group (21.6% vs 9.7%).

28. Moderate ischemic mitral regurgitation

29. The question for moderate cIMR is whether it requires intervention at all?
Will revascularization lead to enough reverse remodeling to stabilize or improve the mitral
regurgitation, or will the risk of cardiotomy and longer cardiopulmonary bypass and cross-
clamp times be more than made up for with faster ventricular remodeling aided by an acute
reduction in volume overload?
In a meta-analysis of 4 randomized controlled trials, including the 1-year outcome of the CTSNet
trial, Wang and colleagues
randomly assigned 301 patients with moderate ischemic mitral regurgitation to CABG alone or
CABG plus mitral-valve repair (combined procedure)
I. no differences in hospital mortality or rates of stroke, and no difference in medium-term mortality
(range 1- to 2.7-year mean follow-up).
II. mitral valve repair groups had lower postoperative NYHA III or IV functional classifications (OR
0.45, P=0.008) and lower rates of residual or recurrent moderate or worse mitral regurgitation
(OR -0.32, P=0.01).

30. Advances in Surgical
Techniques
• Historically, mitral valve replacement was
performed with complete resection of the leaflets
and chordae.
• We now know that preservation of the
subvalvular apparatus with chordal-sparing
techniques improves postoperative
ventricular function and short- and long-term
outcomes.
• However, it is still whether complete chordal-
sparing is necessary or if posterior leaflet
preservation alone is equivalent.

31. • Traditional mitral valve repair involves reduction annuloplasty using a rigid complete
annuloplasty ring that is 1 to 2 sizes smaller than determined by anterior leaflet size and
intertrigonal distance.
• This moves the posterior leaflet anteriorly to improve apposition and coaptation depth with
the anterior leaflet; however, this technique is still associated with poor outcomes in some
series,[53],[91] for a number of possible reasons.
• reduction annuloplasty alone, which although correcting IMR acutely, may contribute to both
short- and long-term recurrence by augmenting posterior leaflet tethering.
• By shifting the posterior annulus anteriorly, the posterior leaflet is pulled away from the posteriorly
and inferiorly displaced posterior papillary muscle, and may actually worsen leaflet tethering and
contribute to the considerable degree of recurrent IMR seen in many studies

32. • Additionally, recent modeling analysis has demonstrated that the reduction annuloplasty may
detrimentally increase inferior LV wall stress.[112] To combat this, a number of techniques have
been studied as both adjuncts and replacements to reduction annuloplasty for repair of IMR.

33. Valvular Techniques:
1. Leaflet augmentation
 The group from Wake Forest reported the use of anterior leaflet augmentation using a 1x3- cm patch in
combination with mitral annuloplasty.
 Although the operative mortality was 12%, the 24- month freedom from recurrent moderate or worse mitral
regurgitation was 82%.
 Others have performed posterior leaflet augmentation for patients with extensive posterior leaflet tethering with
favorable early results. Long-term data for either technique are limited.
2. Edge-to-edge repair is another technique that has been used for patients with IMR.
 Although positive results have been noted with degenerative disease, durability in patients with IMR is influenced by
concomitant use of mitral annuloplasty and the presence of mitral annular calcification and has shown higher rates of
progression of residual disease compared with degenerative disease.

34. Subvalvular Techniques
• Methods of altering the subvalvular apparatus to decrease leaflet tethering, which include
papillary muscle and chordal relocation as well as cutting of secondary chordae, are some of the
most promising adjuncts to reduction annuloplasty for repair of IMR.
 The “ring and sling” method combines mitral valve annuloplasty (ring) with an interventricular
polytetrafluoroethylene sling placed around the base of the papillary muscles, which is tightened to
reduce interpapillary muscle distance and thus tethering and IMR.
 Early data show excellent initial reduction in IMR and perioperative mortality, but long-term data is
mostly lacking.

35. Surgical and External Ventricular Remodeling
• Altough there have been reports of acute reduction in IMR using transverse infarct plication in
combination with CABG,[137],[138] the current European guidelines[109] note that left ventricular
reconstruction techniques have disappointing outcomes in cIMR and are not recommended.
• CorCap Cardiac Support Device
• COAPSYS

37. Refrences:
• STS Ebook
• 2021 ACC/AHA guidelines