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Interventional Cardiology
Percutaneous Mitral Annuloplasty for Treatment of
Functional Mitral Regurgitation
Lutz Buellesfeld,
1
Lazar Mandinov
2
and Eberhard Grube
1
1. Department of Cardiology, HELIOS Heart Centre, Siegburg; 2. Mitralign Inc.
Abstract
Functional mitral regurgitation affects a substantial proportion of patients with congestive heart failure due to myocardial infarction or
dilated cardiomyopathy. Functional mitral regurgitation greatly increases morbidity and mortality. Surgical annuloplasty is the standard of
care for symptomatic patients with moderate or severe functional mitral regurgitation; however, a large number of patients are refused
surgery. Several percutaneous approaches have been developed to address the need for less invasive treatment of mitral annulus
dilatation. Devices using coronary sinus to cinch the mitral annulus are relatively easy to use; however, a number of factors may limit their
clinical application, such as suboptimal anatomical relationship between the coronary sinus and mitral annulus, risk of coronary artery
compression, large variability in the coronary venous anatomy and conflict with other therapies such as ablation or cardiac
resynchronisation. Direct mitral annuloplasty is anticipated to be more effective than the coronary sinus approaches; however, it has yet
to prove its safety and efficacy in carefully designed clinical trials. The best candidates and the best timing for each percutaneous mitral
annuloplasty therapy, whether direct or indirect, have yet to be identified.
Keywords
Functional mitral regurgitation, mitral annulus, percutaneous annuloplasty
Disclosure: Lutz Buellesfeld has no conflicts of interest to declare. Eberhard Grube serves on the Advisory Board of Mitralign Inc. Lazar Mandinovtock is a full-time employee
of Mitralign Inc. and receives stock options.
Received: 22 June 2009 Accepted: 29 June 2009
Correspondence: Lutz Buellesfeld, Department of Cardiology/Angiology, HELIOS Heart Centre Siegburg, Ringstrasse 49, 53721 Siegburg, Germany. E: LuB@gmx.com
Mitral regurgitation (MR) is a complex haemodynamic abnormality patients with MR were more likely than those without MR to
of various aetiologies that may lead to heart failure and sudden experience cardiovascular mortality (29 versus 12%; p<0.001) or
cardiac death.
1–3
The prevalence of MR in unselected populations severe heart failure (24 versus 16%; p=0.0153).
2
In a sub-group
increases with age, from less than 10% among individuals under 40 analysis in the Thrombolysis in Myocardial Infarction (TIMI) trial, MR
years of age to approximately 33% among those over 70 years of was associated with a seven-fold increased risk of mortality.
10
Even
age.
2,4
Most instances of MR found in the general middle-aged mild MR was an independent predictor of cardiac death.
1
population are mild; however, in ageing populations the prevalence
of MR is 13%, and is projected to rise substantially in the years to The mechanisms of FMR are complex. Left ventricular (LV) systolic
come.
3
Mitral valve prolapse, usually resulting from myxomatous dysfunction and remodelling can result in annular dilatation and
connective tissue degeneration, has been estimated to be present papillary muscle displacement with consequent tethering of the mitral
in 4% of the normal population and has replaced rheumatic heart leaflets.
6,11
The papillary muscles are normally aligned directly under
disease as the leading cause of mitral valve regurgitation. the mitral annular area so that they exert a perpendicular force on
Rheumatic fever is now uncommon in the western world, but the leaflets, producing normal coaptation. The final position of the
remains an important aetiology in developing countries.
5
Ischaemic mitral leaflets is determined by the balance of the forces acting on
heart disease is the cause of functional MR (FMR) in one-third to them, including the tethering forces of the annular and papillary
half of all cases. muscles and LV-generated closing forces. With LV remodelling and
papillary muscle displacement, the muscles exert forces in an oblique
Functional Mitral Regurgitation direction, resulting in increased tethering and ineffective coaptation.
12
FMR occurs without any alteration of the structure of the mitral valve This tethering produces a leak in the mitral valve by both causing a
leaflets and is secondary to myocardial dysfunction due to coronary lack of coaptation due to the restricted leaflet motion and creating a
artery disease and myocardial infarction (MI) or dilated change in the geometry of the posterior leaflets with a consequent
cardiomyopathy.
6,7
FMR can be found in 84% of patients with interscallop malcoaptation.
13
Once tethering is increased, leaflet
congestive heart failure (CHF), and in 65% of them the degree of closure is further impaired when less LV contractile force is available
regurgitation is moderate or severe. Several studies have to oppose tethering.
14
The direction and degree of tethering are
documented the strong impact of FMR on early and late survival after critically important for the development of FMR.
14
The
acute MI.
1,2,8,9
In the Survival And Ventricular Enlargement (SAVE) trial, posterior–lateral with apical displacement of the papillary muscles,
© TOUCH BRIEFINGS 2009 67
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