Comparison of mitral annulus geometry between patients with ischemic and non-ischemic functional mitral regurgitation: implications for transcatheter mitral valve implantation

Three-dimensional anatomic features of the mitral valve that predict systolic anterior motion occurring during dobutamine stress echocardiography

BACKGROUND/AIM

Left ventricular outflow tract obstruction related to systolic anterior motion (SAM) of the mitral valve is a common complication of dobutamine stress echocardiography (DSE). However, the mechanisms underlying SAM have not been fully characterized. The objective of the present study was to use three-dimensional echocardiography to identify anatomic features of the mitral valve that predispose to SAM during DSE.

METHODS

We retrospectively evaluated consecutive patients included prospectively in our database and who had undergone 3D echocardiography (including an assessment of the mitral valve) before DSE. Patients who had developed SAM during DSE (the SAM+ group) were matched 2:3 with patients who did not (the SAM- group).

RESULTS

One hundred patients were included (mean age: 67 ± 10). Compared with SAM- patients (n = 60), SAM+ patients (n = 40) had a lower mitral annular area, a smaller perimeter, and a smaller diameter (p < .01 for all, except the anteroposterior diameter). The SAM+ group had also a narrower mitral-aortic angle (126 ± 12° vs. 139 ± 11° in the SAM- group; p < .01) and a higher posterior mitral leaflet length (1.4 ± .27 cm vs. 1.25 ± .29, respectively; p < .01). Furthermore, the mitral annulus was more spherical, more flexible, and more dynamic in SAM+ patients than in SAM- patients (p < .05 for all). In a multivariate analysis of anatomic variables, the mitral-aortic angle, the mitral annular area, and posterior leaflet length were independent predictors of SAM (p ≤ .01 for all). In a multivariate analysis of standard echo and hemodynamic variables, the presence of wall motion abnormalities at rest (p < .01) was an independent predictor of SAM.

CONCLUSION

SAM during DSE is multifactorial. In addition to the pharmacologic effects of dobutamine on the myocardium, 3D echocardiographic features of the mitral valve (a smaller mitral annulus, a narrower mitral-aortic angle, and a longer posterior leaflet) appear to predispose to SAM.

Mitral regurgitation outcomes after transcatheter atrial septal defect closure

BACKGROUND

Worsening mitral regurgitation (MR) is a complication of intervention for atrial septal defect (ASD). Little is known about mitral valve (MV) characteristics associated with worsening MR. We aimed to elucidate MR outcomes and predictors of worsening MR after transcatheter ASD closure.

METHODS

We analyzed changes in MR from prior to transcatheter ASD closure to 6 months after the procedure and predictors of worsening MR via baseline transthoracic echocardiography in 238 patients (64.7% females; mean age, 53 ± 22 years).

RESULTS

Worsening MR was defined as worsening to moderate in patients with less than or equal to mild MR at baseline or vena contracta width increasing of ≥2 mm by 6-month follow-up in patients with moderate MR. Worsening MR was observed in 29 patients (12.2%). The associated echocardiographic findings were pseudoprolapse, hamstringing, stiffness, and anteroposterior and intercommissural mitral annulus diameter in the univariable logistic regression analysis (all P < 0.05). Multivariable analysis after adjusting for age; long-standing persistent atrial fibrillation; and ASD size showed that models combining MV leaflet findings such as pseudoprolapse or hamstringing, or anterior leaflet stiffness with the ratio of the sum of anterior and posterior leaflet lengths to intercommissural mitral annulus diameter were statistically significant for predicting worsening MR (R2 = 0.393, P < 0.001 and R2 = 0.385, P < 0.001, respectively).

CONCLUSIONS

Worsening MR after transcatheter ASD closure might depend on MV leaflet findings and annulus size in patients with long-standing persistent atrial fibrillation.

Functional anatomy and echocardiographic assessment in secondary mitral regurgitation

BACKGROUND

Mitral valve apparatus is complex and involves the mitral annulus, the leaflets, the chordae tendinae, the papillary muscles as well as the left atrial and ventricular myocardium. Secondary mitral regurgitation is a consequence of regional or global left ventricle remodeling due to an acute myocardial infarction (75% of cases) or idiopathic dilated cardiomyopathy (25% of cases). It is associated with an increase in mortality and poor outcome. There is a potential survival benefit deriving from the reduction in the degree of severity of mitral regurgitation. So the correction of the valve defect can change the clinical course and prognosis of the patient. The rationale for mitral valve treatment depends on the mitral regurgitation mechanism. Therefore, it is essential to identify and understand the pathophysiology of mitral valve regurgitation.

AIM OF THE STUDY

The aim of this review is to describe the crucial role of transthoracic and trans-esophageal echocardiography, in particular with three-dimensional echocardiography, for the assessment of the severity of secondary mitral regurgitation, anatomy, and hemodynamic changes in the left ventricle. Moreover, the concept that the mitral valve has no organic lesions has been abandoned. The echocardiography must allow a complete anatomical and functional evaluation of each component of the mitral valve complex, also useful to the surgeon in choosing the best surgical approach to repair the valve.

CONCLUSIONS

Echocardiography is the first-line imaging modality for a better selection of patients, according to geometrical modifications of mitral apparatus and left ventricle viability, especially in preoperative phase.

Dynamic changes of mitral valve annulus geometry at preprocedural CT: relationship with functional classes of regurgitation

BACKGROUND

We investigated mitral valve annular geometry changes during the cardiac cycle in patients with severe mitral regurgitation (MR) who underwent cardiac computed tomography angiography (CCTA) prior to percutaneous mitral valve replacement or annuloplasty.

METHODS

Fifty-one patients with severe MR and high surgical risk (Carpentier classification: 3 type I, 16 type II, 16 type IIIa, 16 type IIIb) underwent multiphase electrocardiographically gated (0-90%) CCTA, using a second generation dual-source CT scanner, as pre-procedural planning. Twenty-one patients without MR served as controls. The mitral valve annulus was segmented every 10% step of the R-R interval, according to the D-shaped segmentation model, and differences among groups were analysed by t-test or ANOVA.

RESULTS

Mitral annular area and diameters were larger in MR patients compared to controls, particularly in type II. Mitral annular area varied in MR patients throughout the cardiac cycle (mean ± standard deviation of maximum and minimum area 15.6 ± 3.9 cm² versus 13.0 ± 3.5 cm², respectively; p = 0.001), with greater difference between annular areas versus controls (2.59 ± 1.61 cm² and 1.98 ± 0.6 cm², p < 0.001). The largest dimension was found in systolic phases (20-40%) in most of MR patients (n = 27, 53%), independent of Carpentier type (I: n = 1, 33%; II: n = 10, 63%; IIIa: n = 8, 50%; IIIb: n = 8, 50%), and in protodiastolic phases (n = 14, 67%) for the control group.

CONCLUSIONS

In severe MR, mitral annular area varied significantly throughout the cardiac cycle, with a tendency towards larger dimensions in systole.

Atrial fibrillation is associated with large beat-to-beat variability in mitral and tricuspid annulus dimensions

AIMS

Beat-to-beat variability in cycle length is well-known in atrial fibrillation (Afib); whether this also translates to variability in annulus size remains unknown. Defining annulus maximal size in Afib is critical for accurate selection of percutaneous devices given the frequent association with mitral and tricuspid valve diseases.

METHODS AND RESULTS

Images were obtained from 170 patients undergoing 3D echocardiography [100 (50 sinus rhythm (SR) and 50 Afib) for mitral annulus (MA) and 70 (35 SR and 35 Afib) for tricuspid annulus (TA)]. Images were analysed for differences in annular dynamics with a commercially available software. Number of cardiac cycles analysed was 567 in mitral valve and 346 in tricuspid valve. Median absolute difference in maximal MA area over four to six cycles was 1.8 cm2 (range 0.5-5.2 cm2) in Afib vs. 0.8 cm2 (range 0.1-2.9 cm2) in SR, P < 0.001. Maximal MA area was observed within 30-70% of the R-R interval in 81% of cardiac cycles in SR and in 73% of cycles in Afib. Median absolute difference in maximal TA area over four to six cycles was 1.4 cm2 (range 0.5-3.6 cm2) in Afib vs. 0.7 cm2 (range 0.3-1.7 cm2) in SR, P < 0.001. Maximal TA area was observed within 60-100% of the R-R interval in 81% of cardiac cycles in SR, but only in 49% of cycles in Afib.

CONCLUSION

MA and TA reach maximal size within a broad time interval centred around end-systole and end-diastole, respectively, with significant beat-to-beat variability. Afib leads to a larger beat-to-beat variability in both timing of occurrence and values of annulus size than in SR.

Geometrical remodeling of the mitral and tricuspid annuli in response to exercise training: a 3-D echocardiographic study in elite athletes

Intense exercise exposes the heart to significant hemodynamic demands, resulting in adaptive changes in cardiac morphology and function. Nevertheless, the athletic adaptation of the atrioventricular valves remains to be elucidated. Our study aimed to characterize the geometry of mitral (MA) and tricuspid (TA) annuli in elite athletes using 3-D echocardiography. Thirty-four athletes presented with functional mitral regurgitation (FMR) were retrospectively identified and compared with 34 athletes without mitral regurgitation (MR) and 34 healthy, sedentary volunteers. 3-D echocardiographic datasets were used to quantify MA and TA geometry and leaflet tenting by dedicated softwares. MA and TA areas, as well as tenting volumes, were higher in athletes compared with controls. MA area was significantly higher in athletes with MR compared with those without (8.2 ± 1.0 vs. 7.2 ± 1.0 cm²/m², P < 0.05). Interestingly, athletes with MR also presented with a significantly higher TA area (7.2 ± 1.1 vs. 6.5 ± 1.1 cm²/m², P < 0.05). Nonplanar angle describing the MA's saddle shape was less obtuse in athletes without MR, whereas the values of athletes with MR were comparable with controls. The exercise-induced relative increases in left ventricular (35 ± 25%) and left atrial (40 ± 29%) volumes were similar; however, the increment in the MA area was disproportionately higher (63 ± 23%, overall P < 0.001). The relative increase in TA area (40 ± 23%) was also higher compared with the increment in right ventricular volume (34 ± 25%, P < 0.05). Atrioventricular annuli undergo a disproportionate remodeling in response to regular exercise. Athletic adaptation is characterized by both annular enlargement and increased leaflet tenting of both valves. There are differences in MA geometry in athletes presented with versus without FMR.NEW & NOTEWORTHY We have characterized the annular geometry of mitral and tricuspid valves in elite athletes using 3-D echocardiography. We have found that exercise-induced remodeling of the atrioventricular annuli comprises a disproportionate dilation of annular dimensions and increased leaflet tenting of both valves. Moreover, we have demonstrated a more pronounced saddle shape of the mitral annulus in athletes without mitral regurgitation, which was not present in those who had mild regurgitation.

Utility of Three-Dimensional Transesophageal Echocardiography for Mitral Annular Sizing in Transcatheter Mitral Valve Replacement Procedures: A Cardiac Computed Tomographic Comparative Study

BACKGROUND

Three-dimensional (3D) transesophageal echocardiographic (TEE) imaging is frequently used as an initial screening tool in the evaluation of patients who are candidates for transcatheter mitral valve replacement (TMVR). However, little is known about the imaging correlation with the gold standard, computed tomographic (CT) imaging. The aims of this study were to test the quantitative differences between these two modalities and to determine the best 3D TEE parameters for TMVR screening.

METHODS

Fifty-seven patients referred to the heart valve clinic for TMVR with prostheses specifically designed for the mitral valve were included. Mitral annular (MA) analyses were performed using commercially available software on 3D TEE and CT imaging.

RESULTS

Three-dimensional TEE imaging was feasible in 52 patients (91%). Although 3D TEE measurements were slightly lower than those obtained on CT imaging, measurements of both projected MA area and perimeter showed excellent correlations, with small differences between the two modalities (r = 0.88 and r = 0.92, respectively, P < .0001). Correlations were significant but lower for MA diameters (r = 0.68-0.72, P < .0001) and mitroaortic angle (r = 0.53, P = .0001). Receiver operating characteristic curve analyses showed that 3D TEE imaging had a good ability to predict TMVR screening success, defined by constructors on the basis of CT measurements, with ranges of 12.9 to 15 cm² for MA area (area under the curve [AUC] = 0.88-0.91, P < .0001), 128 to 139 mm for MA perimeter (AUC = 0.85-0.91, P < .0001), 35 to 39 mm for anteroposterior diameter (AUC = 0.79-0.84, P < .0001), and 37 to 42 mm for posteromedial-anterolateral diameter (AUC = 0.81-0.89, P < .0001).

CONCLUSIONS

Three-dimensional TEE measurements of MA dimensions display strong correlations with CT measurements in patients undergoing TMVR screening. Three-dimensional TEE imaging should be proposed as a reasonable alternative to CT imaging in this vulnerable population.

Relation of Mitral Annulus and Left Atrial Dysfunction to the Severity of Functional Mitral Regurgitation in Patients with Dilated Cardiomyopathy

METHODS

56 patients (58 ± 17 years, 42 men) with DCM and FMR and 52 controls, prospectively enrolled, underwent 3DTTE dedicated for mitral valve (MV), LA, and left ventricle (LV) quantitative analysis.

RESULTS

Patients with FMR vs. controls presented increased MA size and sphericity during the entire systole, whereas MA fractional area change (MAFAC) and MA displacement were decreased (15 ± 5 vs. 28 ± 5%; and 5 ± 3 vs. 10 ± 2 mm, p < 0.001). In patients with moderate/severe FMR, MA diameters correlated with PISA radius, EROA, and regurgitant volume (Rvol), as also did the MA area (with PISA radius, EROA, and Rvol: r = 0.48, r = 0.58, and r = 0.47, p < 0.05). MAFAC correlated inversely with EROA and Rvol (r = -0.32 and r = -0.35, p < 0.05), with both active and total LA emptying fractions and with LV ejection fraction as well. In a stepwise multivariate regression model, decreased MAFAC and increased LA volume independently predicted patients with severe FMR.

CONCLUSIONS

Patients with DCM and FMR have MA geometry remodeling and contractile dysfunction, correlated with the severity of FMR. MA contractile dysfunction correlated with both LA and left LV pumps dysfunctions and predicted patients with severe FMR. Our results provide new insights that might help with better selection of patients for MV transcatheter procedures.