Do flow-gradient groups determined by MDCT predict outcomes: validating CT stroke volume.

Background: Identifying severe aortic stenosis can be difficult especially among patients with low-flow states compared to normal flow. Non-invasive modalities can aid in the diagnosis for timely treatment.

Methods: In this retrospective, single-center study of patients with aortic stenosis who underwent transcatheter aortic valve replacement (TAVR), we calculated stroke volume using CT blood pool based (CT-blp) analysis, echocardiogram and right heart catheterization (cath) performed before TAVR. We compared the performance of each modality in predicting 30-day and 1-year outcomes.

Results: Three-hundred and forty-five patients were included with a median age of 84 (79-88) years and 52.8% females. CT-blp correlated more strongly (r = 0.60) with cath-derived stroke volume than echo (r = 0.37). After stratifying patients into groups based on flow and gradient using echo or CT-blp, there was no difference in mortality with either modality among the groups. However, the composite of mortality and hospital readmission was significantly higher in the low-flow low-gradient group (CT-blp 30-day OR 2.6, 95% CI 1.3-5.3, p < 0.01; 1-year OR 1.9, 95% CI 1.0-3.6; p = 0.04) compared to patients with normal flow high gradients when grouping was performed with CT-blp or echo.

Conclusion: Using the CT performed on patients pre-TAVR, CT-blp can provide an estimation of stroke volume that correlates well with invasive evaluation. The stroke volume may be used to stratify patient populations being evaluated for TAVR into flow gradient groups when echo is limited and avoid invasive catheterization to help identify patients with low-flow, low-gradient aortic stenosis. Further studies with larger cohorts are required to confirm our findings.