Primary Tear Distance From Left Subclavian Artery Predicts Growth in Chronic Type B Aortic Dissection

Abstract

The optimal treatment of acute uncomplicated type B aortic dissection (auTBAD) remains controversial. Currently, thoracic endovascular aortic repair is indicated for the onset of complications. This study investigated whether radiographic characteristics of the primary intimal tear in auTBAD can predict the onset of delayed aneurysm formation. A review of a U.S institutional aortic database from 2000 to 2016 identified 318 auTBADs initially treated with optimal medical therapy. From this cohort, 103 patients with two computed tomography or magnetic resonance imaging scans >6 months apart were available for imaging analysis and were included in this study. These patients were divided into subgroups based on growth of the thoracic aorta ≥1 cm: no growth (n = 46) and growth (n = 57). Twenty-five patients (43.9%) in the growth group underwent open or endovascular intervention. TeraRecon (Foster City, Calif) imaging software was used to analyze characteristics of the primary intimal tear, including the maximum width, maximum length, and distance from the left subclavian artery of the primary tear. Statistical comparisons between groups were performed using χ2, Fisher, Mann-Whitney, and t-tests. The mean age of all patients was 53 ± 11 years, and 70% were male. There were no differences between groups in age, gender, hypertension, diabetes mellitus, tobacco abuse, chronic obstructive pulmonary disease, or renal failure. The mean follow-up was equivalent between the two groups (growth, 33 ± 27 months; no growth, 40 ± 34 months; P = .3). There was no difference in the maximum diameters of the thoracic (growth, 4.4 ± 0.9 cm; no growth, 4.2 ± 0.7 cm; P = .16) or abdominal (growth, 3.7 ± 1.1 cm; no growth, 3.5 ± 0.5 cm; P = .38) aorta at the time of presentation between the two groups. The distance of the primary intimal tear from the left subclavian artery in patients with auTBAD was significantly shorter in the growth group compared with the no growth group (growth, 45 ± 48 mm; no growth, 92 ± 78 mm; P = .001; Fig). There was no difference in the maximum length or width of the primary intimal tear between the two groups (Table). The distance of the primary intimal tear from the left subclavian artery predicts the development of descending thoracic or thoracoabdominal aneurysms in the chronic phase of TBAD. Patients with primary tears located in the distal arch (zone 3) should be monitored more closely and may be considered for early thoracic endovascular aortic repair in the setting of auTBAD.TableRadiographic characteristics of uncomplicated type B aortic dissectionRadiographic characteristicsGrowth (n = 57)No growth (n = 46)P valuePIT distance from left subclavian artery, mm45.4 ± 48.191.5 ± 77.8.001*PIT maximum width, mm11.3 ± 6.610.0 ± 6.9.33PIT maximum length, mm11.7 ± 11.09.5 ± 8.9.28Maximum diameter of thoracic aorta at presentation, cm4.4 ± 0.94.2 ± 0.7.16Maximum diameter of abdominal aorta at presentation, cm3.7 ± 1.13.5 ± 0.5.38PIT, Primary intimal tear. Open table in a new tab