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 pathophysiologically decrease VTI by reducing the pressure gradient between the aorta and LV. This study aimed to determine whether VTI is an echocardiographic marker of AR severity. Methods Study design and population This retrospective cross-sectional observational study was performed over ten months (from January to October 2016). All patients with AR who visited our cardiac imaging laboratory during this period were eligible to participate. Patients had to exhibit moderate to severe AR in a native (non-prosthetic) valve as well as sign an informed consent form to be included in the study. We excluded patients with atrial fibrillation or evidence of any type of arrhythmia, multiple or eccentric jets of AR. The study complied with the declaration of Helsinki and was approved by the ethics committee of our local research panel. Baseline Characteristics of the Population We gathered the following demographic and clinical information from all study participants: age, gender, history of arterial hypertension, dyslipidemia, diabetes mellitus, and smoking habits. Any type of antihypertensive, hypolipidemic, or antiarrhythmic drugs that the subjects were taking at the time of their inclusion in the study was also recorded. During the echocardiogram, the height and weight of each patient were collected, and three arterial blood pressure measurements were taken after 5 minutes of rest, using an M6 Comfort HEM-7221-E8 (Omron Healthcare, Kyoto, Japan) blood pressure monitor – validated through Dabl®Educational Trust and British Hypertension Society protocols –, following the European Society of Hypertension/European Society of Cardiology (ESH/ESC) recommendations. 14 The final arterial blood pressure was the average of the second and third values. Heart rate (HR) was determined at the moment of the measurement of the VTI of AR. All patients also had a blood test performed immediately after collection to determine the plasma creatinine level and calculate the glomerular filtration rate using the CKD-EPI (Chronic Kidney Disease – Epidemiology Collaboration) formula. 15 The blood test analyzer used was a PE Chemistry (Roche Diagnostics, Manheim, Germany). Echocardiographic Variables Echocardiograms were performed on all subjects with an Acuson Siemens SC2000 ultrasound system. We used the Simpson’s biplane method to obtain standard measurements, images, and clips, including left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), and left ventricular ejection fraction (LVEF), in accordance with recommendations from the American Society of Echocardiography. 16 Both thickness and diameter were determined in M-mode with proper alignment whenever possible; otherwise, measurements were made in 2D. The measurement of the VTI of AR flowwas taken using continuous Doppler readings from the view with the best alignment with the regurgitant jet, mainly the apical 5-chamber view (Figure 1) or the parasternal long-axis view in cases of vertical regurgitant jet. Given that HR behaves as a temporal determinant of aortic VTI, the VTI index (VTIi) was calculated in addition to the absolute VTI value by dividing VTI by HR (VTIi=VTI/ HR). The morphology of aortic valves was examined from the parasternal short-axis view. The systolic diameters of the right and left ventricular outflow tract were also measured. Pressure half-time (PHT) was calculated using the apical 5-chamber view. The vena contracta (VC) was estimated with color Doppler in two orthogonal planes, according to the recommendations. 16 ERO was calculated based on the PISA method. 10,17 To that end, images of the regurgitant flow were obtained using the best possible view for the alignment of the convergent flow. When zoomed in at this view, the color Doppler scale was optimized until the isovelocity hemisphere could be adequately differentiated. The PISA radius was measured between the first aliasing circumference relative to the center of the hemisphere in protodiastole, at the exact moment that the regurgitant flow reaches its maximum velocity. The RV was defined as the ERO x VTI product. Additionally, whenever possible, the RV was also determined quantitatively by estimating the aortic and pulmonary systolic volume. 18 The flow reversal in the thoracic aorta was established using Pulse Doppler in the proximal end of the descending aorta through the suprasternal view. Holodiastolic flow with end- diastolic velocity >20 cm/s was considered a positive flow reversal. Finally, following a comprehensive and integrative analysis of the different structural, qualitative Doppler and the semiquantitative parameters obtained and taking into account the latest recommendations, 3,6 two experienced echocardiographers separately quantified the AR. A third experienced echocardiographer assessed and conclusively quantified the AR in case of discordance between the two first cardiologists. Statistical Analysis We tested all variables for normal distribution using the Kolmogorov-Smirnov test. Continuous variables with normal distribution were expressed as mean±standard deviation (SD), and those with skewed distribution as median [interquartile range (IQR)]. Categorical variables were expressed as percentages. Correlations were studied through Spearman’s or Pearson’s method, as appropriate. Inter-rater variability for AR severity quantification was determined by the intraclass correlation coefficient and Bland-Altman plots. 19 Reliability analyses using kappa statistics ( κ ) defined the consistency between the two echocardiographers regarding AR severity (moderate or severe). Baseline differences between moderate or severe AR patients were assessed by unpaired Student’s t -test or Mann–Whitney U test for continuous variables and the χ 2 test for categorical variables. Logistic regression analysis evaluated the association between each baseline variable and severe AR. Multivariate logistic regression models determined the variables independently associated with severe AR. The variables included were those with p<0.05 in the univariate analysis, excluding RV, ERO, and 254