Mitral leaflet separation index in assessing the severity of mitral stenosis

Yeo's index: A novel index that combines anatomic and haemodynamic assessment of the severity of mitral stenosis

BACKGROUND

A mitral leaflet separation index (MLSI), measuring the anatomical separation of the mitral valve (MV) leaflet tips in diastole, was previously described as an accurate method of assessing mitral stenosis (MS). We propose a novel modification of the MLSI by including a hemodynamic assessment which we term Yeo's index that may improve its diagnostic performance.

METHODS AND RESULTS

We retrospectively studied 174 patients with varying severity of MS without significant mitral regurgitation, aortic valve disease or ventricular septal defect. MLSI was measured in 2 orthogonal views on transthoracic echocardiography as previously described. MV dimensionless index (DI) was calculated by dividing the left ventricular outflow tract pulsed-wave Doppler time velocity integral (TVI) by the MV continuous-wave Doppler TVI. We defined Yeo's index as the product of MLSI and DI. With linear correlation, Yeo's index demonstrated good correlation against MVA by planimetry (r = 0.728), pressure half-time (r = 0.677), and continuity equation (r = 0.829), with improved performance over the MLSI. Using ROC analysis, Yeo's index demonstrated good ability to correctly classify MS as severe (MVA ≤1.5cm2) (AUC 0.874, 95% CI 0.816-0.920). Yeo's index ≤0.260 cm correctly classified severe MS with sensitivity of 82% and specificity of 80%. Presence of AF did not affect the performance of Yeo's index. Yeo's index ≤0.147 cm also identified very severe MS (MVA ≤ 1.0 cm2) with specificity of 94% and sensitivity of 78%.

CONCLUSION

Yeo's index performed well in identifying severe MS and may be a useful adjunct to existing measures of MS severity.

Optimal vortex formation time index in mitral valve stenosis

Left ventricular vortex formation time (VFT) is a novel dimensionless index of flow propagation during left ventricular diastole, which has been demonstrated to be useful in heart failure and cardiomyopathy. In mitral stenosis (MS), flow propagation in the LV may be suboptimal. We studied VFT in varying degrees of MS. Echocardiography was performed on 20 healthy controls and 50 cases of rheumatic MS. Patients with atrial fibrillation, LV ejection fraction < 50% and other valvular heart diseases were excluded. VFT was obtained using the length-to-diameter ratio (L/D), where L is the continuous-wave Doppler velocity time integral stroke distance, divided by D, the mitral leaflet separation index. This was correlated against varying degrees of MS severity, left atrial (LA) volume and function. In controls, VFT was 3.92 ± 2.00 (optimal range) and was higher (suboptimal) with increasing severity of mitral stenosis (4.98 ± 2.43 in mild MS; 7.22 ± 2.98 in moderate MS; 11.55 ± 2.67 in severe MS, p < 0.001). VFT negatively correlated with mitral valve area (R² = 0.463, p < 0.001) and total LA emptying fraction (R² = 0.348, p < 0.001), and positively correlated with LA volume index (R² = 0.440, p < 0.001) and mean transmitral pressure gradient (R² = 0.336, p < 0.001). More severe MS correlated with suboptimal (higher) VFT. The restricted mitral valve opening may disrupt vortex formation and optimal fluid propagation in the LV. Despite the compensatory increase in LA size with increasingly severe MS, reduced LA function also contributed to the suboptimal LV vortex formation.

Mitral leaflet separation index for mitral valve assessment during balloon mitral valvuloplasty

OBJECTIVE

The objective of the study was to evaluate the accuracy of the mitral leaflet separation index (MLSI) in selected patients with mitral stenosis, before and after percutaneous balloon mitral valvuloplasty (PBMV), compared to conventional methods with transthoracic echocardiography [TTE].

METHODS

A prospective study was conducted in 30 patients, ages 20-60 years, with severe symptomatic mitral stenosis (MS) who had PBMV in the Cardiology Department, Zagazig University and National Heart Institute. A mean of three to five measurements of MLSI was taken in diastole in the parasternal long-axis and apical four-chamber views. The MLSI was re-measured 24-48 hours after PBMV. We calculated the correlation of the MLSI, pre and post BMV, with two-dimensional (2D) MV planimetry and pressure half-time (PHT) methods to assess MVA.

RESULTS

There was a positive, highly significant correlation between pre PBMV 2D planimetry and MLSI (r = .665, P-value < .001) as well as post PBMV 2D planimetry and MLSI (r = .410, P-value = .025). A positive highly significant correlation was also noted between pre PBMV PHT and MLSI (r = .678, P-value <.001) and between post PBMV PHT and MLSI (r = .706, P-value <.001).

CONCLUSION

Mitral leaflet separation index is an easy and reliable measurement for the assessment of mitral stenosis before and after PBMV.

Mitral leaflet separation to evaluate the severity of mitral stenosis: Validation of the index by transesophageal three-dimensional echocardiography

BACKGROUND

Determining severity of mitral stenosis (MS) by planimetry of mitral valve orifice area (MVA) has been a challenging issue in clinical practice, especially for less experienced cardiologists. Mitral leaflet separation (MLS) has shown a good correlation with MVA measurements. However, it has never been validated against multiplane 3DTEE planimetry (MVA_3D ). We aimed to evaluate the accuracy of MLS index (MLSI_2D ) in predicting MS severity.

METHODS

We prospectively enrolled 144 patients with MS who underwent clinically indicated 2DTTE and 3DTEE. MLSI_2D was yield by averaging the maximal leaflet tip distance in diastole, in parasternal long-axis and apical four-chamber views. MVA_3D was used as the reference method.

RESULTS

MLSI_2D showed an excellent discriminatory ability between different grades of MS (P < .001). There was a significant positive correlation between MLSI_2D and MVA_3D (r = .93, P < .001) irrespective of concurrent mitral regurgitation (r = .94, P < .001) and/or atrial fibrillation (r = .92, P < .001). By receiver operating characteristic (ROC) curves, MLSI_2D  ≤ 8.6 mm showed 100% sensitivity and 76% specificity for very severe MS. MLSI_2D  ≥ 11.2 mm determined progressive MS with 100% sensitivity and 82% specificity. The study population was then divided into a derivation group and a validation group. A regression equation for MVA by MLSI_2D was derived in first group. Then, the MVA was calculated by this equation in validation group and was not significantly different from MVA_3D .

CONCLUSION

MLSI_2D showed an excellent ability to assess MS severity and correlates well with planimetered MVA measured by 3DTEE.

3D Xplane Echocardiographic Technique for Validation of Mitral Leaflet Separation to Assess Severity of Mitral Stenosis

BACKGROUND

Determining the severity of mitral stenosis (MS) is important for both prognostic and therapeutic implications. Mitral valve area (MVA) calculation techniques have more limitations. Mitral leaflet separation (MLS) is a precise and operator friendly alternative to planimetry. In contrast to previous researchers, we have used a novel 3D Xplane technique to validate MLS for assessing the severity of MS. 3D Xplane is superior for validation of MLS due to simultaneous real time acquisition of MLS in parasternal long-axis view and corresponding MVA by planimetry in parsternal short-axis view.

METHODS

It was a prospective observational single center study. A total of 174 patients with MS were evaluated for MVA estimation by various echocardiographic modalities. Maximum leaflet separation and corresponding planimetered MVA were measured using novel 3D Xplane technique.

RESULTS

With 3D Xplane technique, there was strong positive correlation between planimetered MVA and MLS (R = 0.925, P < 0.001), irrespective of coexisting MR (R = 0.886, P < 0.001) or AF (R = 0.912, P < 0.001). Receiver operating characteristic curves of MLS demonstrated AUC for mild and severe MS to be 0.966 and 0.995, respectively. MLS less than 8.62 mm predicted severe MS with 95.5% sensitivity and 94.7% specificity and MLS more than 12.23 mm predicted mild MS with 93.2% sensitivity and 91.4% specificity.

CONCLUSION

In our study, a strong correlation between planimetered MVA and MLS was found using 3D Xplane technique. 3D Xplane thus validates and standardizes MLS by excluding errors due to temporal and spatial variations which are important limitations of 2D echocardiography.