Sizing the mitral annulus in healthy subjects and patients with mitral regurgitation: 2D versus 3D measurements from cardiac CT

Three-dimensional cardiac computed tomography compared with autopsied material for the assessment of the mitral valve

To compare the morphometrical features of non-diseased mitral valves imaged in three-dimensional (3D) cardiac computed tomography with those analyzed macroscopically in autopsied healthy human hearts. A total of 51 cardiac computed tomography scans and 120 adult autopsied human hearts without cardiovascular disease were examined. The 3D reconstruction and visualization software (Mimics Innovation Suite 22, Materialise) was used for heart chambers semi-automatic segmentation and myocardial manual segmentation to visualize a 3D structure of the mitral valve complex and to perform all measurements. Direct comparison of corresponding mitral valve parameters revealed significant differences between obtained results. Significantly larger intercommisural diameter, aorto-mural diameter, and perimeter of the mitral annulus were observed in tomographic scans (all p < 0.0001). However, the intercommissural/aorto-mural diameter ratio showed comparable values for both groups. Nevertheless, the size of anterior mitral leaflet was higher in autopsied material. The height of the P2 scallops was the only parameter that show no significant difference between two groups (p = 0.3). The use of 3D postprocessing algorithms provides a very accurate image of the mitral valve structure, which could be useful for the precise non-invasive assessment of mitral valve size and structure. Three-dimensional contrast enhanced cardiac computed tomography significantly overestimates the measurements of the mitral annulus compared to postmortem analysis.

Three-Dimensional Transthoracic Static and Dynamic Normative Values of the Mitral Valve Apparatus: Results from the Multicenter World Alliance Societies of Echocardiography Study

BACKGROUND

Recent advances in mitral valve (MV) percutaneous interventions have escalated the need for a more quantitative and comprehensive assessment of the MV, which can be best achieved using three-dimensional echocardiography. Understanding normal valve size, structure, and function is essential for differentiation of healthy from disease states. The aims of this study were to establish normative values for MV apparatus size and morphology and to determine how they vary across age, sex, and race groups using data from the World Alliance Societies of Echocardiography Normal Values Study.

METHODS

Three-dimensional volumetric data sets obtained on transthoracic echocardiography in 748 normal subjects (51% men) were analyzed using commercial MV analysis software (TomTec Imaging Systems) to determine annular and leaflet dimensions and areas. The subjects were divided into groups by sex (378 men and 370 women) and age (18 to 40 years [n = 266], 41 to 65 years [n = 249], and >65 years [n = 233]) to identify sex- and age-related differences. In addition, differences among black, white, and Asian populations were studied. Inter- and intraobserver variability was assessed in a subset of 30 subjects and expressed as mean absolute difference between pairs of repeated measurements.

RESULTS

Compared with women, men had larger annular size measurements, larger tenting size parameters, and larger leaflet length and area. Compared with the black and white populations, the Asian population showed significantly smaller mitral annular size. Although many of the age, sex, and race differences in MV parameters were statistically significant, they were comparable with or smaller than the corresponding measurement variability. Indexing to body surface area and height did not eliminate these differences consistently, suggesting that parameters may need to be indexed according to their dimensionality.

CONCLUSIONS

This analysis of the World Alliance Societies of Echocardiography data provides normative values of mitral apparatus size and morphology. Although sex- and age-related differences were noted, they need to be interpreted with caution in view of the associated measurement variability.

Tricuspid annular dimensions in patients with severe mitral regurgitation without severe tricuspid regurgitation

Background

Concomitant TV repair during mitral valve (MV) surgery based on tricuspid valve annulus (TVA) dilation, rather than the degree of tricuspid regurgitation (TR), is beneficial and supported by the valve guidelines. We sought to determine TVA geometry and dimensions in controls and assess the changes that occur in patients with severe primary (PMR) and secondary (SMR) mitral regurgitation without TR.

Methods

We analyzed cardiac computed tomographic angiography (CCTA) of 125 consecutive subjects: 50 controls with normal coronary CCTA and no valvular dysfunction, 50 PMR patients referred for robotic repair, and 25 SMR patients referred for transcatheter therapy. Patients with >2+ TR on echocardiography were excluded. Annular measurements were performed using dedicated software and compared. Correlations and determinants of TVA dimensions were analyzed.

Results

Patients with SMR were older and had significantly more comorbidities. In controls, the TVA was larger and more planar and eccentric compared to the MV annulus (all P<0.01). Dimensions of both annuli correlated significantly (r≥0.5; P<0.001 for all dimensions) in controls and patients with severe MR. In both PMR and SMR, the TVA enlarged in all dimensions (P<0.01) with a trend towards becoming more circular. On multivariable regression, the MV annular area was the primary determinant of the TVA area (adjusted β=0.430, P<0.001).

Conclusions

Substantial changes in TVA dimensions are encountered in patients with severe MR even in the absence of severe TR such that TVA and MVA dimensions remain correlated. Close attention to the TVA in patients with severe MR is warranted.

Mitral annular calcification in the elderly - Quantitative assessment

PURPOSE

To determine the reliability of subjective and objective quantification of mitral annular calcification (MAC) in elderly patients with severe aortic stenosis, to define quantitative sex- and age-related reference values of MAC, and to correlate quantitative MAC with mitral valve disease.

METHODS

In this retrospective, IRB-approved study, we included 559 patients (268 females, median age 81 years, inter-quartile range 77-85 years) with severe aortic stenosis undergoing CT. Four independent readers performed subjective MAC categorization as follows: no, mild, moderate, and severe MAC. Two independent readers performed quantitative evaluation of MAC using the Agatston score method (Agatston_MAC). Mitral valve disease was determined by echocardiography.

RESULTS

Subjective MAC categorization showed high inter-reader agreement for no (k ​= ​0.88) and severe MAC (k ​= ​0.75), whereas agreement for moderate (k ​= ​0.59) and mild (k ​= ​0.45) MAC was moderate. Intra-reader agreement for subjective MAC categorization was substantial (k ​= ​0.69 and 0.62). Inter- and intra-reader agreement for Agatston_MAC were excellent (ICC ​= ​0.998 and 0.999, respectively), with minor inconsistencies in MAC involving the left ventricular outflow tract/aortic valve. There were significantly more women than men with MAC (n ​= ​227, 85% versus n ​= ​209, 72%; p ​< ​0.001), with a significantly higher Agatston_MAC (median 597, range 81-2055 versus median 244; range 0-1565; p ​< ​0.001), particularly in patients ≥85 years of age. Agatston_MAC showed an area-under-the-curve of 0.84 to diagnose mitral stenosis, whereas there was no association of Agatston_MAC with mitral regurgitation (p ​> ​0.05).

CONCLUSIONS

Our study in elderly patients with severe aortic stenosis shows that quantitative MAC scoring is more reliable than subjective MAC assessment. Women show higher Agatston_MAC scores than men, particularly in the elderly population. Agatston_MAC shows high accuracy to diagnose mitral stenosis.

A fully automated software platform for structural mitral valve analysis

OBJECTIVE

To evaluate a novel fully automated mitral valve analysis software platform for cardiac computer tomography angiography (CCTA)-based structural heart therapy procedure planning.

METHODS

The study included 52 patients (25 women; mean age, 66.9 ± 12.4 years) who had undergone CCTA prior to transcatheter mitral valve replacement (TMVR) or surgical mitral valve intervention (replacement or repair). Therapeutically relevant mitral valve annulus parameters (projected area, circumference, trigone-to-trigone (T-T) distance, anterior-posterior (AP) diameter, and anterolateral-posteromedial (AL-PM) diameter) were measured. Results of the fully automated mitral valve analysis software platform with and without manual adjustments were compared with the reference standard of a user-driven measurement program (3mensio, Pie Medical Imaging). Measurements were compared between the fully automated software, both with and without manual adjustment, and the user-driven program using intraclass correlation coefficients (ICC). A secondary analysis included the time to obtain all measurements.

RESULTS

Fully automated measurements showed a good to excellent agreement (circumference, ICC = 0.70; projected area, ICC = 0.81; T-T distance, ICC = 0.64; AP, ICC = 0.62; and AL-PM diameter, ICC = 0.78) compared with the user-driven analysis. There was an excellent agreement between fully automated measurement with manual adjustments and user-driven analysis regarding circumference (ICC = 0.91), projected area (ICC = 0.93), T-T distance (ICC = 0.80), AP (ICC = 0.78), and AL-PM diameter (ICC = 0.79). The time required for mitral valve analysis was significantly lower using the fully automated software with manual adjustments compared with the standard assessment (134.4 ± 36.4 s vs. 304.3 ± 77.7 s) (p < 0.01).

CONCLUSION

The fully automated mitral valve analysis software, when combined with manual adjustments, demonstrated a strong correlation compared with the user-driven software while reducing the total time required for measurement.

KEY POINTS

• The novel software platform allows for a fully automated analysis of mitral valve structures. • An excellent agreement was found between the fully automated measurement with manual adjustments and the user-driven analysis. • The software showed quicker measurement time compared with the standard analysis of the mitral valve.

Integrated imaging of echocardiography and computed tomography to grade mitral regurgitation severity in patients undergoing transcatheter aortic valve implantation

Aims

Quantitative mitral regurgitation (MR) grading remains challenging. This study evaluated the concept of integrating echocardiography and computed tomography for grading MR severity. Specifically, an integrated parameter was developed that combines the true cross-sectional mitral regurgitant orifice area (ROA) assessed with multi-detector row computed tomography (MDCT) with flow data from echocardiography.

Methods and results

Systolic MDCT data of 73 patients, referred for transcatheter aortic valve implantation (TAVI) who also had MR, were evaluated. The MDCT systolic phase with the smaller left ventricular volume and the largest mitral regurgitant orifice was selected. Using planimetry, the mitral ROA was measured. The mitral ROA was multiplied with the velocity time integral of the MR jet on echocardiography for the calculation of the integrated regurgitant volume (RVol). MDCT analysis showed a mean mitral ROA of 11.3 ± 7.4 mm2 and a mean integrated RVol of 21.4 ± 14.7 mL/beat, whereas echocardiography showed a mean effective ROA and RVol of MR of 13.3 ± 8.2 mm2 and 23.9 ± 13.6 mL/beat, respectively. Compared with echocardiography, grading based on integrated mitral RVol resulted in reclassification of 10% of the patients from severe to non-severe MR and 14% of the patients from non-severe to severe MR.

Conclusions

Integrated mitral RVol is a quantitative parameter of MR severity by combining the true cross-sectional mitral ROA assessed with MDCT and Doppler mitral haemodynamics which resulted in a significant reclassification of MR grade in patients with severe aortic stenosis undergoing TAVR.

Role of MDCT Imaging in Planning Mitral Valve Intervention

PURPOSE OF REVIEW

Recent advancements in transcatheter valvular interventions have resulted in a growing demand for advanced cardiac imaging to help guide these procedures.

RECENT FINDINGS

Both echocardiography and multi-detector computed tomography have played essential roles in the maturation of transcatheter aortic valve replacement and are now building on these experiences and helping inform the nascent field of transcatheter mitral interventions. Advanced imaging is essential to aid in the diagnosis and determination of the mechanism of mitral regurgitation. In addition, they are integral to annular sizing, determination of the suitability of patient anatomy for specific devices and increasingly important in the determination of the risk of left ventricular outflow tract obstruction and providing appropriate patient-specific fluoroscopic angulation in advance of the procedure.

Changes in mitral annular morphology and function in young patients with type 1 diabetes mellitus-results from the three-dimensional speckle tracking echocardiographic MAGYAR-Path Study

BACKGROUND

Alterations in mitral annular size and function could be demonstrated in cardiomyopathies and ischaemic heart disease. The present study was designed to evaluate mitral annulus (MA) morphology and function in young type 1 diabetes mellitus (T1DM) patients by three-dimensional speckle tracking echocardiography (3DSTE) and to compare their results to matched healthy controls.

METHODS

The study comprised 18 patients with T1DM (mean age: 33.0±8.0 years). Their results were compared to that of 20 age- and gender-matched healthy controls (mean age: 37.8±10.9 years). Complete two-dimensional (2D) Doppler echocardiography and 3DSTE have been performed in all cases.

RESULTS

No significant differences could be demonstrated in demographic and standard echocardiographic parameters between the groups. Significantly enlarged diastolic MA diameter (2.87±0.27 mm vs. 2.58±0.32 mm, P=0.01), MA diameter index 1.61±0.20 cm/m(2) vs. 1.30±0.39 cm/m(2), P=0.008, and MA area index (4.81±0.88 cm(2)/m(2) vs. 3.91±1.35 cm(2)/m(2), P=0.03) could be demonstrated in T1DM together with augmented MA fractional shortening (28.64±9.63% vs. 20.35±12.50%, P=0.05).

CONCLUSIONS

Early alterations in MA size and function could be demonstrated in young patients with T1DM by 3DSTE.

A simplified D-shaped model of the mitral annulus to facilitate CT-based sizing before transcatheter mitral valve implantation

BACKGROUND

The nonplanar, saddle-shaped structure of the mitral annulus has been well established through decades of anatomic and echocardiographic study. Its relevance for mitral annular assessment for transcatheter mitral valve implantation is uncertain.

OBJECTIVE

Our objectives are to define the methodology for CT-based simplified "D-shaped" mitral annular assessment for transcatheter mitral valve implantation and compare these measurements to traditional "saddle-shaped" mitral annular assessment.

METHODS

The annular contour was manually segmented, and fibrous trigones were identified using electrocardiogram-gated diastolic CT data sets of 28 patients with severe functional mitral regurgitation, yielding annular perimeter, projected area, trigone-to-trigone (TT) distance, and septal-lateral distance. In contrast to the traditional saddle-shaped annulus, the D-shaped annulus was defined as being limited anteriorly by the TT distance, excluding the aortomitral continuity. Hypothetical left ventricular outflow tract (LVOT) clearance was assessed.

RESULTS

Projected area, perimeter, and septal-lateral distance were found to be significantly smaller for the D-shaped annulus (11.2 ± 2.7 vs 13.0 ± 3.0 cm(2); 124.1 ± 15.1 vs 136.0 ± 15.5 mm; and 32.1 ± 4.0 vs 40.1 ± 4.9 mm, respectively; P < .001). TT distances were identical (32.7 ± 4.1 mm). Hypothetical LVOT clearance was significantly lower for the saddle-shaped annulus than for the D-shaped annulus (10.7 ± 2.2 vs 17.5 ± 3.0 mm; P < .001).

CONCLUSION

By truncating the anterior horn of the saddle-shaped annular contour at the TT distance, the resulting more planar and smaller D-shaped annulus projects less onto the LVOT, yielding a significantly larger hypothetical LVOT clearance than the saddle-shaped approach. CT-based mitral annular assessment may aid preprocedural sizing, ensuring appropriate patient and device selection.