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 2 – Clinical and Echocardiographic Characteristics of the Low Flow Low Gradient Aortic Stenosis Patients with Flow Variation calculated by both methods ≥ |15| % with Dobutamine Infusion Low Flow Low Gradient Aortic Stenosis with Classic and Alternative ΔQ ≥ |15|% (n = 9) Demographics and Physical Examination Age, yr 73 ± 7,1 Male sex, n (%) 6 (67) Weight, Kg 67 ± 13,0 Height, cm 162 ± 5,8 Body surface area, m 2 1,70 ± 0,164 Hemodynamic Indices Basal Peak Dobutamine Heart rate, bpm 67 ± 10,6 81 ± 19,8 Systolic Blood Pressure, mmHg 113 ± 23,9 134 ± 35,2 Diastolic Blood Pressure, mmHg 60 ± 12,6 58 ± 14,1 Classic Q, mL/s 174 ± 45,3 155 ± 42,3 Alternative Q, mL/s 254 ± 55,5 242 ± 56,7 SV, mL 47 ± 13,9 65 ± 15,0 SVI, mL/m 2 28 ± 6,9 38 ± 8,4 LVEDV, mL 155 ± 74,9 129 ± 46,6 LVESV, mL 107 ± 47,2 72 ± 25,6 LVEF, % 30 ± 9,5 42 ± 13,7 Indices of Aortic Stenosis Severity Basal Peak Dobutamine V max , m/s 3,2 ± 0,47 4,0 ± 0,64 G mean , mmHg 24 ± 5,7 39 ± 13,9 VTI Ratio 0,20 ± 0,056 0,27 ± 0,066 EOA, cm 2 0,68 ± 0,185 0,94 ± 0,238 EOAi, cm 2 /m 2 0,40 ± 0,093 0,55 ± 0,126 Classification of Aortic Stenosis in Terms of Severity True Severe Low Flow Low Gradient AS, n (%) 4 (44) Pseudo-Severe Low Flow Low Gradient AS, n (%) 2 (22) Persistent Area-Gradient Mismatch Low Flow Low Gradient AS, n (%) 3 (33) Simplified Aortic Valve Area at flow rate 250 mL/min Classic EOA proj , cm 2 0,94 ± 0,246 Alternative EOA proj , cm 2 0,98 ± 0,248 Data are presented as mean ± standard deviation or number (%) of patients, as appropriate. ΔQ: variation of flow rate from the baseline with dobutamine infusion, presented as fractional change (%); 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. the aortic velocity spectrum. Also, as it only requires 2 different measurements, it is less prone to increased inter-observer and intra-observer variability. This study aimed to assess how much the EOA proj calculated using an alternative method to estimate flow rate differs from the EOA proj calculated by the standard formula. The Bland-Altman method was used to assess agreement between the two methods. As previously published, Pearson correlation and linear regression analysis can be misleading in terms of assessing agreement between two measurement methods, as data which seem to be in poor agreement (for instance, a change in scale of measurement) can be highly correlated. 6,9 Bland-Altman method assesses how well the methods agree on average 136