Comprehensive 4D-flow cardiac magnetic resonance evaluation of the descending thoracic aorta in aortic regurgitation.

Aims: To assess the reproducibility of 4D-Flow cardiac magnetic resonance (CMR) parameters in the descending thoracic aorta-DTAo-(regurgitant fraction [RF], end-diastolic reverse flow [EDRF], and holodiastolic flow reversal [HDR]), and the relationship with RF in the sinotubular junction (STJ), and the left ventricular end-diastolic volume index (LVEDVI) in patients with chronic aortic regurgitation (AR).

Methods and results: A descriptive study of these variables was conducted. A receiver operating characteristic curve was used to determine the optimal cut-off point. Thirty patients had severe AR (RF ≥ 30%, STJ) and 60 mild-to-moderate (RF < 30%). The mean age was 59 ± 17 years. Left ventricular ejection fraction (LVEF) was 56% (53-61%) and LVEDVI was 94 (76-128) mL/m². Flow in the DTAo at the left inferior pulmonary vein (LIPV) was easily identifiable and measurements were highly reproducible. The intraclass correlation coefficient was 0.969 (95% CI: 0.954-0.980) for RF and 0.929 (95% CI: 0.893-0.952) for EDRF. Flow parameters measured at the LIPV were all significantly greater in the severe AR group: RF (21% vs. 6%, P < 0.001), EDRF (20 vs. 4 mL/s; P < 0.001), and HDR (20% vs. 8%; P < 0.001). Three parameters-presence of HDR, RF ≥ 17%, and EDRF ≥ 7 mL/s at the LIPV-were associated with RF ≥ 30% in the STJ and elevated LVEDVI.

Conclusion: 4D-flow CMR can reproducibly assess flow in the DTAo in patients with chronic AR. An RF ≥ 17%, EDRF ≥ 7 mL/s, and/or the presence of HDR in the DTAo (LIPV) were associated with an RF ≥ 30% in STJ and elevated LVEDVI.