ABC | Volume 110, Nº2, February 2018

Original Article Ferreira et al Alternative method to calculate simplified EOA proj Arq Bras Cardiol. 2018; 110(2):132-139 Table 1 – Clinical and echocardiographic characteristics of the low-flow low-gradient aortic stenosis patients at baseline and at 20 ug/Kg/min Dobutamine infusion Low Flow Low Gradient Aortic Stenosis (n = 22) Demographics and Physical Examination Age, yr 72 ± 8.8 Male sex, n (%) 15 (68) Weight, Kg 71 ± 12.7 Height, cm 163 ± 8.4 Body surface area, m 2 1.76 ± 0.183 Hemodynamic Indices Basal Peak Dobutamine Heart rate, bpm 66 ± 8.9 80 ± 18,9 Systolic Blood Pressure, mmHg 115 ± 20.7 139 ± 31,3 Diastolic Blood Pressure, mmHg 62 ± 12.1 64 ± 18,9 Classic Q, mL/s 202 ± 63.3 236 ± 56,3 Alternative Q, mL/s 169 ± 51.2 223 ± 53,9 SV, mL 54 ± 16.0 62 ± 14,4 SVI, mL/m 2 30 ± 8.4 35 ± 8,7 LVEDV, mL 145 ± 56.9 136 ± 41,7 LVESV, mL 97 ± 42.9 79 ± 38,5 LVEF, % 33 ± 9.8 43 ± 15,3 Indices of Aortic Stenosis Severity Basal Peak Dobutamine V max , m/s 3.2 ± 0.50 3,9 ± 0,55 G mean , mmHg 24 ± 7.3 37 ± 12,2 VTI Ratio 0.22 ± 0.06 0,25 ± 0,07 EOA, cm 2 0.43 ± 0.091 0,49 ± 0,116 EOAi, cm 2 /m 2 0.44 (0.35 – 0.50) 0,46 (0,43 – 0,54) Classification of Aortic Stenosis in Terms of Severity True Severe Low Flow Low Gradient AS, n (%) 8 (36) Pseudo-Severe Low Flow Low Gradient AS, n (%) 3 (14) Persistent Area-Gradient Mismatch Low Flow Low Gradient AS, n (%) 11 (50) Simplified Aortic Valve Area at flow rate 250 mL/min Classic EOA proj , cm 2 0.93 ± 0.220 (n = 14) * Alternative EOA proj , cm 2 0.98 ± 0.238 (n = 14) ** Data are presented as mean ± standard deviation or number (%) of patients, as appropriate. Classic Q: flow rate calculated by the classic formula; Alternative Q: flow rate calculated by the alternative formula; SV: stroke volume; SVI: stroke volume index; LVEDV: left ventricular end diastolic volume; LVESV: left ventricular end systolic volume; LVEF: left ventricular ejection fraction; V max : maximum velocity of aortic Doppler spectrum; G mean : transaortic mean pressure gradient; VTI Ratio: velocity time integral ratio; EOA: effective orifice aortic valve area; EOAi: indexed effective orifice aortic valve area; Classic EOA proj : simplified projected aortic valve area calculated using the classic flow rate formula; Alternative EOA proj : simplified projected aortic valve area calculated using the alternative flow rate formula; AS: aortic stenosis. * Only 14 patients had a flow rate variation with dobutamine infusion estimated with the classical formula ≥ |15| %, enabling the calculation of the classic EOA proj . ** Only 14 patients had a flow rate variation with dobutamine infusion estimated with the alternative formula ≥ |15| %, enabling the calculation of the alternative EOA proj. formula involves measurements acquired in different places and, inevitably, in different time points, encompassing an intrinsic bias. Flow rate can also be determined by the product of left ventricular outflow tract area and left ventricular outflow tract mean velocity, which requires only 2 measurements: 1) LVOT D and 2) mean velocity of blood at LVOT during the ejection period (LVOT Vmean ). LVOT Vmean is given automatically in most echocardiography software when assessing LVOT VTI (a fundamental step in EOA calculation by the continuity equation). This alternative formula is less cumbersome to calculate as it does not need an additional measurement in 135