Relationship Between Aortic Valve Calcification and Hemodynamic Severity of Aortic Stenosis: Effect of Aortic Valve Phenotype and Age - PROGRESSA Study -
BACKGROUND: Aortic valve calcification (AVC) measured by computed tomography (CT) is useful to assess actual severity (anatomic severity) of aortic stenosis (AS) in patients with discordant hemodynamic parameters or uncertain grading at echocardiography. However, impact of aortic valve phenotype (tricuspid vs. bicuspid) and age on the relationship between AVC and hemodynamic severity remains unknown. We hypothesized that the relationship between AVC and hemodynamic severity of AS is influenced and modulated by aortic valve phenotype and age.
METHODS: Two hundred (200) patients with AS and preserved left ventricular ejection fraction (LVEF) underwent a comprehensive Doppler echocardiography and CT in the context of the prospective PROGRESSA study. Mean transvalvular gradient (MG) measured by Doppler was used to assess AS hemodynamic severity. AVC was determined by the Agatston method and indexed to the LV outflow tract area to obtain AVC density (AVCd). AVCd was used to assess AS anatomic severity. Since it has been previously shown that relationship between AVC and hemodynamic severity is influenced by sex, statistical analyses were all stratified according to sex.
RESULTS: Thirty-nine (39) patients had a bicuspid aortic valve (BAV). The correlation between MG and AVCd was modest (r=0.44, p<0.0001) in the whole cohort. Analyzed by the valve phenotype, correlation was good between AVCd and MG in the TAV group (r=0.63, p<0.0001) but non-significant in the BAV group (r=0.24, p=0.14). Median age was 51 and 72 years for BAV and TAV patients respectively. In the TAV group, the strength of the AVCd-MG correlation was similar in younger (<72 y.o.; r=0.63, p<0.0001) vs. older (≥72 y.o.; r=0.60, p<0.0001) patients. In the BAV group, there was no correlation between AVCd and MG in the younger patients (<51 y.o.; r=-0.005, p=0.99), whereas there was a strong correlation in the older patients (≥51 y.o.; r=0.67, p=0.0009).
CONCLUSIONS: CT AVC correlates well with hemodynamic severity of AS in TAV and in older BAV patients. Hence in these patients, AVC or AVCd measured by CT is a reliable parameter to corroborate AS severity in patients who have uncertain or discordant findings at echocardiography. False negative results may be observed with CT AVC in younger BAV patients. Corroboration of echo grading of AS severity by CT is however rarely needed in this population.