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Abstract 17072: A Novel Algorithm for Quantification of Mitral Valve Regurgitation Based on Pixel Density Analysis of Continuous Wave Doppler Imaging


 Introduction:
 Echocardiography is important for the assessment of mitral valve regurgitation (MR) and to guide clinical decision making. Echocardiographic methods are being used to quantify MR severity but their applicability, accuracy, and reproducibility have been debated.
 
 
 Hypothesis:
 To test the feasibility and in vitro validation of a novel custom-made transthoracic echocardiographic method for the assessment of MR severity based on pixel density analysis (PDA) of the continuous wave (CW) envelope in digital images.
 
 
 Methods:
 MR was prospectively assessed in 290 patients on a VIVID E9 echo machine (GE) with fixed settings. MR severity was evaluated according to international guidelines using color doppler, vena contracta (VC) width, proximal iso-velocity surface area (PISA) method, and PDA. The applicability, inter-observer, and intra-observer variability of all methods were compared. For validation of the PDA algorithm, a pulsatile in vitro cardiac phantom was used with prosthetic mitral valves with different regurgitant orifices (13.2, 27.2, 54.7, and 86.5 mm2). Regurgitant volume (RV) was calculated by multiplying the regurgitant orifice with the time velocity integral.
 
 
 Results:
 The PDA method showed a linear correlation with color doppler (r=0.82), VC width (r=0.67), PISA-effective regurgitant orifice area (EROA, r=0.72), and PISA-RV (r=0.67); p<0.001 for all. The PDA was significantly more applicable than VC width (n= 275/290, 95% vs. 218/290, 75% p<0.001) and PISA-based methods (n=191/290, 65% p<0.001). Additionally, PDA showed a stronger intra- and inter-observer agreement compared to the VC, PISA-EROA, and PISA-RV (intra-observer ICC = 0.96 vs. 0.79, 0.87, and 0.82 respectively; inter-observer ICC = 0.96 vs. 0.46, 0.89, and 0.85 respectively). In the in vitro validation, PDA showed a strong linear correlation with regurgitant volumes (r=0.92, p<0.001).
 
 
 Conclusions:
 We showed the clinical feasibility and in vitro validation of a novel digital quantitative echocardiographic method to assess MR severity. This method is more applicable and has less inter- and intra-observer variability compared to current quantitative methods. Patient follow-up is ongoing to validate the novel methods against clinical endpoints in MR.
