1. Long-term Result of Acute Type B Aortic Dissection Department of Cardiovascular Surgery, Hyogo Brain and Heart Center at Himeji, Hyogo Brain and Heart Center at Himeji, Hyogo, Japan Shunsuke Miyahara Yuya Tauchi Naoto Izawa Masaomi Fukuzumi Naoto Morimoto Hirohisa Murakami Tasuku Honda Keitaro Nakagiri Masato Yoshida Nobuhiko Mukouhara Nobuhiko Mukouhara

2. Background Patients with Stanford type B dissection, treated medically during the acute phase, have the risk of late aortic events, such as surgery and aortic rupture. We investigated predictors of late aortic events, focusing on the status of the false lumen at the time of onset.

3. Objective September 2000～May 2009 191 consecutive acute type B aortic dissections Surgical interventions in acute phase: 22 cases Surgery for other true aneurysms : 5 cases Follow up interval < 6 months : 4 cases ＜Exclusion Criteria ＞ Acute type B aortic dissection 160 cases Age 66.1±11.6 y.o Female 37 cases (23.1%) Follow-up 44.6±25.4 mo.

4. Patients and Methods Acute type B aortic dissection N=160 Group T :Thrombosed false lumen without ULP N=49(30.6%) Group U ：Thrombosed false lumen+ULP N=52(32.5%) Group P：Patent false lumen N=59(36.9%)

5. Characteristics Group TGroup UGroup P Age (y.o)69.5±8.9 n.s 70.5±7.9 p<0.0001 60.0±15.4 p=0.0002 Sex(Female%)36.7 p=0.028 17.3 n.s 16.9 p=0.020 Peripheral artery disease (%) 4.1 n.s 13.4 n.s 8.5 n.s Hyper tension (%)34.7 n.s 38.4 n.s 30.5 n.s Ischemic heart disease (%) 6.1 n.s 5.8 n.s 5.1 n.s Maximum aortic diameter at onset (mm) 36.5±5.1 p<0.0001 41.5±6.0 p=0.037 39.0±6.3 p=0.028

6. Growth Length of Maximum Aortic Diameter ⊿Diameter(mm) Follow up (mo.) T:-0.016±0.23mm/mo. U:0.40±0.91mm/mo. P:0.44±0.49mm/mo. n.s P<0.0001 P=0.0024

7. Freedom from Aortic Events Follow-up 33.6±20.5 mo. N 49 40 29 17 10 5244 35 22 12 7 59 46 37 28 21 15 5 0.2.4.6.8 1 Freedom from Aortic Event 0102030405060708090 Months T U P P=0.0011 P=0.0004 P=0.9558 Descending aortic replacement 10 Thoracoabdominal aortic replacement 8 Total arch replacement 5 TEVAR 3 Abdominal aortic replacement 1 Rupture 4 Other 1

8. Survival Follow-up 44.6±25.4mo. 0.2.4.6.8 1 Survival 020406080100120 Months N 49 42 29 22 13 52 48 31 18 9 5 59 43 36 29 22 17 10 93.8% 5years 78.7% 5years 91.9% 5years T U P P=0.670 P=0.4386 P=0.1243 Rupture 4 SAH 3 Respiratory failure 3 Pneumonia 2 Malignancy 2 Trauma 1 Heart failure 1 Rena failure 1 Sudden death 1

9. Statistical Analysis of Predictors for Late Aortic Events 0.4402 DeBakey Ⅲ a 0.2119Hyper Tension 0.4013Peripheral artery diseases 0.1468Ischemic Heart Disease 1.260-72.8049.5780.0290.0002Patent false lumen or ULPs 1.091-1.2151.151<0.0001 Max diameter at onset 0.1221Aortic dilation in distal arch 0.5117Female 0.941-0.9900.9650.00690.0103Age 95% CI*Hazard Ratio P valueUnivariate pVariables *CI: Confidence Interval Cox Proportional Hazard Analysis

10. Maximum Aortic Diameter at Onset Maximum Aortic Diameter at Onset (mm) 40.5mm Sensitivity for Late Aortic Events Specificity for Late Aortic Events ROC Curve 0.743 P<0.001 95%CI 0.642-0.844

11. Cases ①59y.o Female Group T Thrombosed false lumen without ULP resulted in regression. 12mo. 27mo. ②63y.o Male Group U ULP progressed to saccular aneurysm in distal arch. 6mo. ③74y.o Male Group U ULP in thrombosed false lumen recanalized into patent false lumen. 34mm 30mm 47mm59mm

12. Conclusions Incidence of late aortic events is higher in patients with thrombosed false lumen complicated by ULPs as well as those with patent false lumen, especially with a maximum aortic diameter >40mm at onset. Careful and regular follow-up CT examinations are needed and surgical interventions should be taken into account for these entities.