Outer Media Thickness at False Lumen and Secondary Aortic Dilatation After Acute Aortic Dissection

BACKGROUND This study measured the outer media thickness (OMT) at the false lumen by using microscopic images of specimens collected intraoperatively and assessed the impact of OMT on secondary dilatation of the downstream aorta. METHODS Of 238 patients undergoing surgical procedures for acute type A dissection between 2007 and 2016, 129 patients fulfilled the inclusion criteria for this study: DeBakey type I dissection with a patent false lumen, histopathologic examination of full-thickness aortic wall, and at least 1 follow-up computed tomographic scan at more than 3 months after surgical procedures. On average, 5.1 scans were obtained per patient, and median follow-up was 4.3 years. RESULTS Considerable variation was observed in OMT (median, 0.21 mm; range, 0.04-0.51 mm). The aortic diameter growth rate was inversely correlated with the OMT, and in the lowest tertile of OMT the aortic diameter dilated significantly faster in the first year than later and faster than in the other tertiles. Multivariable Fine-Gray analysis, with death as the competing risk, identified OMT as an independent variable for aortic-related events. Patients with OMT of 0.04 to 0.15 mm had a 3.54-fold higher risk of aortic-related events and those with 0.16 to 0.31 mm had a 1.56-fold higher risk of aortic-related events than did patients with OMT of 0.32 to 0.51 mm. Multivariable Cox regression analyses revealed OMT of 0.04 to 0.15 mm as an independent variable for all-cause mortality. CONCLUSIONS In patients with DeBakey type I aortic dissection with a patent false lumen, the growth rate of the distal residual dissecting aorta was inversely correlated with the OMT. The risk of aortic-related events was significantly higher in patients with OMT of 0.04 to 0.15 mm.

Automated summary

This study measured the outer media thickness (OMT) of the false lumen in patients with DeBakey type I aortic dissection and found that OMT was inversely correlated with the growth rate of the distal dissecting aorta. Patients with OMT of 0.04 to 0.15 mm had a significantly higher risk of aortic-related events.