ABC | Volume 115, Nº2, August 2020

Original Article Abellán-Huerta et al. Velocity-time integral of aortic regurgitation Arq Bras Cardiol. 2020; 115(2):253-260 and LVEF (Table 4). LVESD and left ventricular end-systolic volume were excluded from the multivariate analysis due to collinearity with LVEDD (r p =0.905, p<0.001) and LVEDV (r p =0.871, p<0.001), respectively. We also excluded ERO, RV, and VC from the multivariate analysis as they could not be obtained for all patients due to poor ultrasound window or difficulty in measuring. This model showed greater discrimination (Statistic C=0.837, 95%CI 0.728–0.947) and an accurate calibration (Hosmer-Lemeshow χ 2 =2.30, p=0.970). On the other hand, since HR and DBP could pathophysiologically influence the VTI measurement (DBP as a determinant of velocity, and HR of time), the association between VTI and AR severity was assessed adjusting for HR and DBP. VTI was also inversely related to AR severity, irrespective of these factors (OR 0.232, 95%CI 0.056–0.961, p=0.044). Finally, the VTIi of AR also showed an inverse association with AR severity (Table 3) and acted as a marker of AR severity, regardless of LVEDD, LVEDV, and LVEF in the multivariate analysis (Table 4). Additionally, this variable was also related to AR severity, irrespective of DBP (OR<0.001, 95%CI <0.001–0.001, p=0.029). Discussion This study suggests that the VTI of AR can be used as a marker of severity in patients with significant AR, considering that estimating severity through echocardiography is a difficult process involving the integration of several different tests and parameters. 2-4,20 Effectively, ERO by the PISA method works as a parameter for the stratification of AR severity, 3,7 and an indirect relationship can be found between ERO and VTI (ERO=RV/VTI). 3,10 More severe AR presents a larger ERO and RV, but the behavior of VTI is unknown. In this study, the VTI of the aortic regurgitant flow was inversely associated with AR severity. The scientific evidence available corroborating this relationship is scarce. Zarauza et al. 21 published a study that assessed the value of VTI of AR, amongst other parameters, in a sample of 43 patients with moderate to severe AR. 21 Their findings were similar to ours (severe AR VTI: 1.8±0.7 m vs. 1.9±0.5 m; moderate AR VTI: 2.2±0.8 m vs. 2.2±0.5 m, respectively). However, in the study by Zarauza et al., 21 the differences between VTI in severe and moderate AR did not reach statistical relevance. The difference in sample size for patients with moderate AR Figure 1 – Measurement of the velocity-time integral of aortic regurgitation flow from the apical 5-chamber view. MnPG: mean pressure gradient; PG: maximum pressure gradient; Vmax: maximum aortic regurgitant flow velocity; VTI: velocity-time integral of aortic regurgitation. 257