Normal flow, low gradient aortic stenosis - is LVOT the determinant?

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Severe aortic stenosis is characterized for a high mean gradient (>40mmHg) and an aortic valve area (AVA ≤1cm2). These patients present with a lower mean gradient (<40mmHg) and area (AVA ≤1cm2). However, the treatment strategies focus on the population with a reduced indexed stroke volume (≤35mL/m2). There is less clarity concerning those with a normal stroke volume. An important determinant of the area and stroke volume is the LVOT diameter, which may have a significant impact in the classification of the severity. There is some literature supporting an expected diameter according to the body surface area. Purpose This paper aims to analyse the population with normal flow, low gradient aortic stenosis, as well as compare the impact of the expected LVOT diameter in the classification of patients. Methods We present a retrospective study from all consecutive patients to whom an echocardiogram was performed in our hospital during the years 2017 and 2018 which meet the criteria for low gradient aortic stenosis. Comorbidities were analysed as well as echocardiographic variables to properly characterize aortic stenosis. Results A total of 79 patients met the criteria for normal flow, low gradient aortic stenosis with a valvular area ≤1cm2. Mean age was 79.5 ± 8.6 years-old and 38% was male. The mean LVOT diameter was 2.11 ± 0.18 cm which correlated to a mean AVA of 0.88 ± 0.10 cm2. Should the LVOT diameter align with the expected diameter according to the formula [(5,7× BSA +12,1)/10], the mean LVOT diameter would be 2.18 ± 0.11 cm, which correlated to a mean AVA of 0.96 ± 0.22cm2. This represents a statistically significant difference in the value, with the expected diameter being 0.075cm higher than the measured (p = 0.002), which translates in a statistically significant higher AVA (+0.085, p < 0,001). With the above data, 31 (38.8%) patients would have been reclassified as moderate aortic stenosis, according to the recalculated AVA alone. Taking into account the indexed AVA, only 22 (27.8%) patients would be reclassified. 8 other patients (10.1%) would have been reclassified as low flow, low gradient aortic stenosis as the recalculated stroke volume would be lower than 35mL/m2. Conclusion This paper reminded us of the importance of an appropriately measured LVOT diameter, and the potential impact in reclassification of valvular heart disease. This is more important when the classification may alter our conduct. Other imaging techniques, such as transoesophageal echocardiogram or CT scan, may obviate the squared error of the LVOT measurement as well as account for the geometry of the LVOT, especially in dubious cases. Abstract Figure.