Assessment of the re-entry tear index as a prognostic indicator for renal perfusion improvement after thoracic endovascular aortic repair in patients with acute and subacute Stanford type b aortic dissection with renal artery involvement.

Background: Aortic dissection is the most common acute aortic syndrome, and renal artery is the most common involved artery. The size and location of the re-entry tear directly affect the blood flow enhancement of the false lumen branch artery after surgery. In this study, the morphology and hemodynamics of the re-entry tear were comprehensively analyzed, and the location and size of the re-entry tear were quantitatively evaluated to calculate the re-entry tear index (RTI). This study aimed to assess the predictive capability of a comprehensive quantitative RTI for improvement in renal perfusion following thoracic endovascular aortic repair (TEVAR) in cases of acute and subacute Stanford type B aortic dissection with renal artery involvement.

Methods: In this prospective cohort study, 137 patients diagnosed with acute or subacute type B aortic dissection with concomitant renal artery involvement who underwent TEVAR at Anzhen Hospital in Beijing from October 2017 to November 2021 were enrolled. Renal blood flow was estimated quantitatively with ultrasound. Based on the ultrasound findings of renal artery flow, the patients were classified into two groups: group A [postoperative volume flow (VolFlow) reduced compared to preoperative VolFlow] and group B (postoperative VolFlow increased compared to preoperative VolFlow). All re-entry tears present in the aortic trunk according to reconstructed computed tomography angiography (CTA) obtained preoperatively were included in the analysis. The general information of patients, whether the involved renal artery arose partially or wholly from the false lumen, the proximal diameter and length of the covered stent, the diameter of primary entry tear, the RTI, etc. were analyzed. Univariate and multivariate logistic regression analyses were executed to assess the risk factors associated with increased renal arterial blood flow subsequent to TEVAR. Additionally, receiver operating characteristic (ROC) curve analysis was used to ascertain the optimal cutoff value and predictive efficacy of the RTI.

Results: A total of 137 patients, comprising of 32 with acute and 105 with subacute type B aortic dissection accompanied by renal artery involvement, underwent TEVAR. Among these patients, 44 (32.1%) were assigned to group A and 93 (67.9%) to group B. Renal blood flow exhibited an increase in 67.9% of the patients after TEVAR. The results of multivariate analysis indicated that the RTI is an independent risk factor for postoperative renal perfusion improvement [odds ratio =17.66; 95% confidence interval (CI): 2.13-78.55; P=0.020]. The optimal cutoff value for RTI, determined to be 0.033, demonstrated the ability to identify renal perfusion improvement in patients without hypertension with a sensitivity of 53.7% and a specificity of 68.9%. In patients with concomitant hypertension, RTI exhibited a sensitivity of 96.6% and a specificity of 60.0%, with an area under the ROC curve (AUC) of 0.792 (95% CI: 0.643-0.941; P=0.021) for identifying renal perfusion improvement.

Conclusions: RTI demonstrated a favorable predictive value for improving renal malperfusion following TEVAR in cases of aortic dissection with renal artery involvement.