P1827Maximum systolic flow deceleration rate in the false lumen by 4D-flow MRI is associated with aortic dilatation in patients with chronic descending aorta dissection

Abstract Introduction Patent false lumen (FL) in aortic dissection has been associated with poor prognosis mainly due to aortic expansion. Although morphologic variables have been related to aortic dilatation as expression of high pressure in the FL, they do not reflect flow characteristics. We propose the maximum systolic flow deceleration rate (MSDR) in the FL, quantified by 4Dflow, assuming that flow should be strongly decelerated during systole under high pressure. Methods Twenty-nine patients with a patent FL after aortic dissection (no Marfan syndrome) and with a follow-up of at least 3 years underwent a contrast-enhanced 4D-flow MR. FL acceleration was calculated during the cardiac cycle in a sub-volume of the descending aorta (5 cm around the level of the pulmonary bifurcation). MSDR was determined as the maximum minus the minimum acceleration in systole over the corresponding time interval (Figure 1a). Aortic growth rate (GR) was defined as the difference between final and initial aortic diameters obtained by angio-CT over the period of follow-up. Population was divided into tertiles based on GR. Results Demographic, clinical variables or basal aortic diameter did not show differences among GR groups (Table 1). MSDR was statistically different in patients with a GR <1mm/year (group 1) compared to fast-dilating patients (groups 2, 3) (Figure 1c). MSDR showed a positive linear correlation with GR resulting in a Pearson's correlation of 0.481 (p=0.008) (Figure 1b). Table 1. Demographic and other variables Tertile 1 Tertile 2 Tertile 3 p-value Age (year) 63.4 (±13.5) 62.5 (±13.6) 64.6 (±6.7) 0.902 BSA (m2) 2.0 (±0.2) 1.8 (±0.2) 1.9 (±0.1) 0.213 Men 6 (86%) 4 (57%) 4 (100%) 0.210 Hypertension 4 (66%) 5 (71%) 4 (100%) 0.438 Atherosclerosis 1 (17%) 1 (14%) 0 (0%) 0.699 Initial diameter 45.0 (±7.69) 36.0 (±4.2) 37.0 (±6.5) 0.078 Final diameter 49.5 (±6.74) 44.9 (±5.7) 59.2 (±9.8) 0.049* Follow-up (year) 11.8 (±8.79) 7.9 (±3.3) 8.1 (±4.0) 0.921 Aortic GR (mm/year) 0.3 (±0.3) 1.2 (±0.3) 2.6 (±1.0) 0.001* MSDR (cm/s3) 1212 (±468) 2411 (±1034) 2558 (±1098) 0.005* Values are mean (±SD) or n (%). Conclusion MSDR of flow in the FL derived from 4D-flow RM is related to GR of dissected descending aorta. It is useful to discriminate mild vs. significant aorta enlargement and identify patients who may benefit from earlier therapy.