Mitral regurgitation (MR) is a common valvular heart disorder and conveys significant excess morbidity and mortality.1,2 Guidelines for transthoracic echocardiography (TTE) underscore the importance of quantifying MR severity, preferably using a multiparametric approach.3 This includes the vena contracta width (VCW), the effective regurgitant orifice area (EROA), and regurgitant volume (RV), most commonly assessed with the proximal isovelocity surface area (PISA) method.3 These methodologies rely on single-frame acquisitions and therefore inherently ignore dynamic variations in MR flow during systole, which can be significant.4,5 Notably, MR flow may occur exclusively at the beginning (protosystolic MR) or at the end of systole (telesystolic MR) or can be present during the entire systole (holosystolic MR), albeit often with significant flow variation. While several echocardiographic methods have been developed to evaluate MR flow variation throughout systole, their intricacy and time-consuming nature limit their use in routine clinical practice.4,6,7

In patients with mitral valve prolapse (MVP), the continuous-wave Doppler (CWD) signal of the MR jet is prototypical to illustrate telesystolic MR. Here the duration of the visible part of the CWD signal may provide a rough estimate of MR flow variation, as the contour of the Doppler spectrum is easily demarcated by clear differences in pixel intensities between proto-midsystole and telesystole.3,8,9 Accordingly, in telesystolic MVP-MR, it is advised to trace only the clearly visible part of the CWD spectrum to measure the time-velocity integral (TVI) for calculating either the MR volume (RV) for the PISA method or the EROA in the case of the two-dimensional or Doppler volumetric method.2,3,10, 11, 12 However, in many patients, more subtle fluctuations in pixel intensities occur in the CWD signal throughout systole (Figure 1). In fact, in clinical practice, the TVI is mostly obtained irrespective of pixel variations throughout the CWD spectrum (which likely reflects variable MR flow during systole), and therefore TVI does not account for MR flow variation.9,10,13,14

Therefore, the aim of the present study was to investigate whether the assessment of MR regurgitant flow variation is feasible through the assessment of the temporal changes in pixel intensity of the MR-CWD using a pixel variation score (PVS). Next, we investigated whether this PVS echocardiographic index relates to MR hemodynamics and MR severity and whether PVS is a clinically meaningful parameter with respect to outcome in patients with MVP and FMR.