Relationship of Mitral Annular Remodeling to Severity of Chronic Mitral Regurgitation

Transthoracic echocardiography for arrhythmic mitral valve prolapse: Phenotypic characterization as first step

Mitral valve prolapse (MVP) is the most frequent valvulopathy with a prevalence of 1.2%-2.4% in general population and it is characterized by a benign course. Although it can be associated with some complications, ventricular arrhythmias (VA) and sudden cardiac death (SCD) as ultimate expressions, are the most worrying. The estimated risk of SCD in MVP is between 0.2% and 1.9% per year including both MVP patients with left ventricular (LV) dysfunction due to severe MR and MVP patients without significant MR. The latter ones constitute a particular phenotype called "malignant MVP" characterized by bileaflet myxomatous prolapse, ECG repolarization abnormalities and complex VAs (c-VAs) with polymorphic/right bundle branch block morphology (RBBB) and LV fibrosis of the papillary muscles (PMs) and inferobasal wall secondary to mechanical stretching visualized as late gadolinium enhancement (LGE) areas by cardiac magnetic resonance (CMR). In MVP, the first diagnostic approach is transthoracic echocardiography (TTE) that defines the presence of mitral annular disjunction (MAD) which seems to be associated with "arrhythmic MVP" (AMVP). From an ECG point of view, AMVP is characterized by frequent premature ventricular contractions (PVCs) arising from one or both PMs, fascicular tissue, and outflow tract, as well as by T-wave inversion in the inferolateral leads. The aim of the present paper is to describe TTE red flags that could identify MVP patients at high risk to develop complex arrhythmias as supported by the corresponding findings of LGE-CMR and anatomy studies. TTE could be a co-partner in phenotyping high-risk arrhythmic MVP patients.

Assessment of Mitral Annulus Size and Function by Real-time 3-Dimensional Echocardiography in Cardiomyopathy: Comparison with Magnetic Resonance Imaging

OBJECTIVE

We sought to assess mitral annular (MA) size and function in hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) using real-time 3-dimensional (3D) echocardiography (RT3DE).

METHODS

The study included 30 patients with HCM, 20 patients with DCM, and 30 control subjects. RT3DE measurements included end-systolic and end-diastolic MA area (MAA) (MAA(3D)), MA diameter(3D), MA fractional area change (MAFAC), and MA fractional shortening. In subgroup of 50 patients, magnetic resonance imaging (MRI) was used for MAA(MRI) and MA diameter(MRI) measurement.

RESULTS

End-diastolic MAA(3D) was larger in HCM than in control group (P < .0001). Higher MAFAC and MA fractional shortening were present in HCM than in control group (P = .001 and P = .006, respectively). End-systolic and end-diastolic MAA(3D) in DCM were higher than in HCM and control groups (P < .0001). Lower MAFAC and MA fractional shortening were present in DCM than in HCM and control groups (P < .0001). MAFAC correlated well with left ventricular function in control subjects (r = 0.94, P < .0001), whereas correlation was less in DCM (r = 0.53, P = .02) and HCM (r = 0.42, P < .01). RT3DE and MRI measurements were comparable.

CONCLUSION

RT3DE assessment of MA size and function in control subjects and patients with cardiomyopathy is accurate and well correlated with MRI.

Mitral Annular Remodeling with Varying Degrees and Mechanisms of Chronic Mitral Regurgitation

HYPOTHESES

Degree of mitral annular remodeling is directly associated with severity of chronic mitral regurgitation (MR). Mitral annular remodeling occurs in a symmetric fashion, regardless of MR severity. In addition to MR severity, MR mechanism plays a significant role in mitral annular remodeling.

BACKGROUND

Limited data exists on mitral annular remodeling in patients with MR. Identification of annular changes may be important in aiding surgical repair.

METHODS

Mitral annular dimensions (anteroposterior, intercommissural, surface area, and circumference) were measured in end systole and diastole using 3-dimensional reconstructive software in 83 patients: trace to no MR (23), mild MR (15), moderate MR (26), and severe MR (19). Annular sphericity indices were determined by dividing intercommissural by anteroposterior dimensions. Patients were further subgrouped by mechanism of MR.

RESULTS

With increasing MR severity, there was a corresponding increase in all annular measurements, most pronounced in the anteroposterior dimension, circumference, and area. Larger increases were seen in patients with prolapse/flail and dilated mechanisms. Furthermore, the mitral annulus became more circular (sphericity index approached 1.0) with increasing MR severity. Patients with prolapse/flail mechanisms exhibited normal left ventricular volumes despite significant annular enlargement.

CONCLUSIONS

Mitral annular remodeling is directly associated with MR severity and occurs in an asymmetric fashion, yet is not limited to one region of the annulus. Mechanism of MR plays a significant role in annular remodeling. Annular remodeling can occur independently of left ventricular remodeling.

True mitral annulus diameter is underestimated by two-dimensional echocardiography as evidenced by real-time three-dimensional echocardiography and magnetic resonance imaging

BACKGROUND

Mitral annulus assessment is of great importance for the diagnosis and treatment of mitral valve disease. The present study sought to assess the value of real-time three-dimensional echocardiography for the assessment of true mitral annulus diameter (MAD).

METHODS

One hundred and fifty patients (mean age 38 +/- 18 years) with adequate two-dimensional (2D) echocardiographic image quality underwent assessment of MAD(2D) and MAD(3D) (with real-time three-dimensional echocardiography). In a subgroup of 30 patients true MAD was validated with magnetic resonance imaging (MRI).

RESULTS

There was a good interobserver agreement for MAD(2D) (mean difference = -0.25 +/- 2.90 mm, agreement: -3.16, 2.66) and MAD(3D) (mean difference = 0.29 +/- 2.03, agreement = -1.74, 2.32). Measurements of MAD(2D) and MAD(3D) were well correlated (R = 0.81, P < 0.0001). However, MAD(3D) was significantly larger than MAD(2D) (3.7 +/- 0.9 vs. 3.3 +/- 0.8 cm, P < 0.0001). In the subgroup of 30 patients with MRI validation, MAD(3D) and MAD(MRI) were significantly larger than MAD(2D) (3.3 +/- 0.5 and 3.4 +/- 0.5 cm vs. 2.9 +/- 0.4 cm, both P < 0.001). There was no significant difference between MAD(MRI) and MAD(3D).

CONCLUSION

MAD(3D) can be reliably measured and is superior to MAD(2D) in the assessment of true mitral annular size.