P910An Asian perspective on left ventricular outflow tract cut-offs and the resulting discrepancy in severity grading of aortic stenosis

Objectives Inconsistencies in grading of aortic stenosis (AS) severity have been reported based on measurement of left ventricular outflow tract diameter (LVOTd), but this remains to be studied in an Asian population. We investigated consistency of grading AS severity at various LVOTd, and subsequently postulated alternative cut-offs for more consistent grading of AS severity. Methods 350 consecutive patients with index echocardiographic diagnosis of severe AS were divided them into three groups based on LVOTd: “small” (<20mm), “average” (20–22mm), “large” (>22mm). In each group, the consistency of flow-dependent (transaortic mean pressure gradient (MG)) and flow-independent parameters (AVA) were used for classification of AS severity. Results Of 350 patients, 51.7% had small LVOTd, while 30.8% and 17.5% had average and large LVOTd respectively. Consistent grading by LVOTd based on AVA and MG, was seen in 33.7% of patients with small, 47.6% with average, 57.7% with large LVOTd. When the hypothetical AVA cut-off of 0.9cm2 was used, consistent grading improved to 38.0% in small, 56.5% in average and 70% in large LVOTd. At an AVA cut-off of 0.8cm2, there was further incremental improvement in the small LVOTd group to 54.1% (p<0.05). Table 1. Consistent grading by LVOTd based on current guidelines Small LVOTd (<20mm, n=181) Average LVOTd (20–22mm, n=108) Large LVOTd (>22mm, n=61) Consistent grading AVA < cut-off MG >40 Consistency (%) Consistent grading AVA < cut-off MG >40 Consistency (%) Consistent grading AVA < cut-off MG >40 Consistency (%) n=61 33.7 n=51 47.6 n=35 57.7 n=69 38 n=61 56.5 n=43 70* n=98 54.1*+ n=70 65.1* n=43 70.8* *p-value <0.05 when compared with AVA cut-off 0.8cm2 for each LVOTd category; +p-value <0.05 when compared with AVA cut-off 0.9cm2 for each LVOTd category. Figure 1 Conclusion Current severe AS guidelines are most consistent with those in the large LVOTd group. However, the majority of the study's Asian population is in the small LVOTd group, which is the group most susceptible to discrepancy in AS grading. Improved consistency in echocardiographic grading may be attained with a lower AVA cut-off in this Asian cohort.