Average pixel intensity method for prediction of outcome in secondary mitral regurgitation

The Pixel Variation Score: An Echocardiographic Index to Assess Temporal Variation of Mitral Regurgitant Flow

BACKGROUND

In mitral regurgitation (MR), temporal variation of MR flow has been considered an important reason for inaccurate MR grading. Current echocardiographic methods for assessing temporal MR flow variation are complex, and their clinical relevance has not been investigated. In this study, we investigated whether assessing MR flow variation using a dimensionless index with echocardiography is feasible, clinically meaningful, and related to patient outcomes.

METHODS

Consecutive patients with mitral valve prolapse (MVP, n = 244) and functional MR (FMR, n = 396) underwent comprehensive echocardiography. Mitral regurgitation severity was assessed using an integrated approach advocated by current guidelines. The MR continuous-wave Doppler envelope was divided into 3 segments of equal duration. Each segment's pixel intensity was assessed to calculate the pixel variation score (PVS).

RESULTS

The PVS was lower in FMR patients than in MVP patients. Lower PVS was associated with worse MR, larger left atrial and left ventricular dimensions, lower ejection fraction, and higher pulmonary artery pressures. In MVP, PVS was significantly associated with postoperative left ventricular reverse remodeling and was able to reclassify most patients in whom single-frame measures overestimated MR severity. Finally, PVS had incremental prognostic value on top of clinical and echocardiographic predictors of outcome.

CONCLUSIONS

Temporal variation in MR flow can reliably be assessed with echocardiography through analysis of the continuous-wave Doppler signal. A high PVS value may alert the echocardiographer to defer from single-frame MR grading and also suggests that the MR is probably not severe.

Prognostic value of myocardial work and global longitudinal strain in patients with heart failure and functional mitral regurgitation

In patients with heart failure and functional mitral regurgitation (FMR), the assessment of left ventricular (LV) function is important for risk stratification and decision making. As LV ejection fraction (LVEF) might not be an optimal metric for LV systolic performance in this population, alternatives such as global longitudinal strain (GLS) and global myocardial work index (GWI) have been proposed. In the present study, we investigated the prognostic value of GLS and GWI and compared these measures to other LV systolic performance parameters. A prospective and consecutive cohort of 181 patients (median age 72 years, 76% male) with LVEF < 50% and FMR underwent comprehensive echocardiographic examination including speckle tracking echocardiography and grading of FMR severity. During a median follow-up of 42 months, 72 cardiovascular (CV) events occurred. In univariate analysis, LVEF, GLS, GWI, mitral S', LV outflow tract time velocity integral, forward LVEF and LV ejection time were associated with CV events. After multivariate adjustment only GLS (hazard ratio (HR) = 0.884, p = 0.015) and GWI (HR = 0.927, p = 0.034) remained independently associated with CV events. There was no difference in the incremental prognostic value of GWI compared to GLS (delta -2 log likelihood = 0.8; p = 0.37). In this cohort of heart failure patients with FMR, GLS and GWI were independently associated with cardiovascular events, whereas other systolic performance parameters were not. However, GWI did not outperform GLS, and further research is required to determine the value of these strain-based measures in clinical practice.

Diagnostic and Prognostic Value of Several Color Doppler Jet Grading Methods in Patients With Mitral Regurgitation

Color Doppler is a widely used ultrasound imaging method for assessing mitral regurgitation (MR) in clinical practice. Nevertheless, color Doppler-based grading of the MR jet has been rarely considered in clinical studies. We investigated the diagnostic and prognostic value of several color Doppler MR jet grading methods and compared them with quantitative grading of MR. The MR color Doppler jet was assessed in 476 MR patients using an 'integrated' eyeballing approach by quantifying the color Doppler jet area, jet area/left atrium area and jet length and using quantitative methods. Clinical endpoints were scored as major adverse clinical events, including cardiovascular death, heart failure hospitalization and mitral valve intervention. When assessed by three echocardiographers, there was a moderate inter-observer agreement for eyeballing color Doppler grade of MR (intraclass correlation coefficient 0.69, p < 0.001). The intra-observer agreement was good for all color Doppler approaches. In primary MR, eyeballing color Doppler correlated well with (in)direct measures of MR severity, with a negative predictive value of 91% when using a grade 2 color Doppler as cut-off. In secondary MR, eyeballing color Doppler grade and jet length were predictors of clinical outcome in Cox proportional hazards analysis (p = 0.003), independent of pulmonary pressures, atrial and ventricular volumes. Overall, the integrated eyeballing approach performed better than color Doppler quantification of the MR jet area and length. In conclusion, this study shows that color Doppler grading of the distal MR jet performs well in predicting events in primary and secondary MR, compared to quantitative grading methods.

Proportionate or disproportionate secondary mitral regurgitation: how to untangle the Gordian knot?

Recent randomised percutaneous mitral intervention trials in patients with heart failure with secondary mitral regurgitation (SMR) have yielded contrasting results. A 'relative load' or 'proportionality' conceptual framework for SMR has been proposed to partly explain the disparate results. The rationale behind the framework is that SMR depends on the left ventricular dimension and not vice versa. In this review, we provide an in-depth analysis of the proportionality parameters used in this framework and also discuss the regurgitant fraction. We also consider haemodynamic observations in SMR that may affect the interpretation and comparisons among proportionality parameters. The conclusion is that the proportionality concept remains hypothetical and requires prospective validation before envisaging its use at individual patient level for risk stratification or therapeutic decision-making.