P296 The effect of ideal BSA in patients with moderate aortic stenosis

Abstract INTRODUCTION The current obesity epidemic has an impact on calculated BSA. Obesity significantly increases the calculated BSA from what the ideal BSA would be if based on a patient’s ideal body weight. PURPOSE To determine the effect of ideal BSA on AV area index in patients with moderate aortic stenosis and normal left ventricular function. METHODS Our ECHO database was searched for all patients with an LVEF >50% and moderate aortic stenosis based on a mean aortic gradient of 20-39 mmHg and an AV area >1.00 cm2. Patients with more than mild aortic regurgitation, previous valvular repair or replacement, significant mitral valve disease or any LV wall motion abnormalities were excluded. Ideal weight was calculated using the Devine formula = Constant + 2.3 x [height in inches-60], where constant= 50Kg in males and 45.5Kg in females). Body surface area in m2 was calculated using the formula = [√ (height in cm x weight in Kg)/3600]. The paired t-test was used to determine differences between means and the Fisher’s exact test was used to determine differences between proportions. A p value of <0.05 was considered significant. RESULTS There were 210 females (mean age 75.4 ± 11.9 years, mean AV gradient 25.3 ± 4.8 mmHg, mean AVA 1.28 ± 0.27 cm2) and 385 males (mean age 72.7 ± 11.3 years, mean AV gradient 25.9 ± 5.2 mmHg, mean AVA 1.32 ± 0.28 cm2). Other important variables are seen in table 1. There were highly significant differences between actual and ideal measurements of weight, BSA and AV area index. Based on the actual BSA there were 151 of 385 male patients (39.2%) with severe aortic stenosis (<0.60 cm2/m2), which dropped to 66 of 385 patients (17.1%) when the ideal BSA was used in the calculation (P < 0.0001, Fisher’s exact test). For females there were 44 of 210 patients with severe aortic stenosis (21.0%) which dropped to 3 (1.4%) when the ideal BSA was used in the calculation (P < 0.0001, Fisher’s exact test). CONCLUSIONS Use of the ideal BSA, based on ideal weight, significantly reclassifies women in terms of AS severity and will be consistent throughout time. All mean aortic gradients and AV areas, by definition, and 98.6% of the ideal AV area indices being in the moderate AS range. The data is less compelling in males but is still significantly improved with 82.9% of AV area indices being correctly assigned. Table 1. Weight/kg (Females) Weight/kg (Males) BSA/m2 (Females) BSA/m2 (Males) AVAI (Females) AVAI (Males) Actual. 77.5 ± 21.4 90.1 ± 16.9 1.79 ± 0.23 2.04 ± 0.20 0.72 ± 0.16 0.65 ± 0.14 Ideal. 51.6 ± 6.2 69.3 ± 7.1 1.51 ± 0.12 1.83 ± 0.14 0.85 ± 0.17 0.73 ± 0.16 P value. <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 AVAI = Aortic valve area index (cm2/m2). BSA = Body surface area (m2).