Quantitative Doppler Shape Analysis in Functional Tricuspid Regurgitation.

Background: The shape of the continuous wave Doppler (CWD) envelope in functional tricuspid valve regurgitation (fTR) results from the dynamic interplay between flow, pressure gradient and impedance. Although the v-wave cut-off shape in fTR is a well-recognized feature of severe TR, the complete spectrum of TR CWD shapes across the different fTR severity ranges has not been thoroughly explored, which is the scope of the present study.

Methods: In 245 patients with fTR, TR was graded with transthoracic echocardiography using the corrected proximal isovelocity surface area method and CWD shapes were scored, both qualitatively (using visual scoring into parabolic, triangular or v-wave cut-off categories) and quantitatively using a novel Vmax/Vmean parameter and time-to-peak velocity corrected for TR duration (TTP/TRD). Linear regression analysis was performed to identify associations of Vmax/Vmean and TTP/TRD. Vmax/Vmean was categorized into tertiles to assess its association with the composite endpoint of death and heart failure hospitalization. Survival analysis consisted of Kaplan-Meier curves with log-rank tests and a multivariate Cox regression model.

Results: The Vmax/Vmean ratio as a surrogate value for fTR CWD shapes increases from a parabolic shape (1.26 ±0.07) towards a more triangular shape without v-wave (1.32 ±0.10) and eventually the v-wave cut-off sign (1.42 ±0.14, P<0.001) in most severe fTR. Vmax, EROA and RV function parameters are significantly associated with Vmax/Vmean and TTP/TRD. Vmax/Vmean is independently associated with the occurrence of the composite endpoint (adjusted HR 1.32, 95% CI: 1.09-1.60 (P = 0.004), log rank P = 0.004 between the second (1.27-1.33) and third tertile (>1.33)). Hierarchical Cox models show no incremental value on top of EROA (P = 0.2), whereas TTP/TRD was not associated with outcome.

Conclusion: Vmax/Vmean reflects the hydraulic severity of fTR and is independently associated with adverse clinical outcomes, providing a simple tool for improved risk stratification in patients with fTR.