1. Remodeling of the Remnant Aorta after Acute Type A Aortic Dissection Surgery
Are Young Patients More Likely to Develop Adverse Aortic Remodeling of the Remnant Aorta Over Time?
Suk Jung Choo¹, Jihoon Kim¹, Sun Kyun Ro², Joon Bum Kim¹,
Sung-Ho Jung¹, Cheol Hyun Chung¹, Jae Won Lee¹
1 Thoracic and Cardiovascular Surgery, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea;
2 Thoracic and Cardiovascular Surgery, Hanyang University Guri Hospital, Hanyang University College of Medicine, Gyeonggi-do, Korea

2. Background Acute aortic dissection in young patients?
Adverse aortic remodeling after acute type A aortic dissection in younger ages may be more extensive in its course than in advanced age
Young age vs old age: tissue characteristic.
Cystic medial necrosis, 진단 된 Marfan, bicuspid 외에 진단이 안 된 connective tissue or familial
aortic disease가 있을 수 .
Old age: degenerative atherosclerosis.

3. Enrollment: Jan 1999 - Dec 2013 190 162 124 F/U > 1 month 76.5%
Acute type A aortic dissection
Ascending and/or hemiarch replacement
162
Pre- and post- operative chest CT (+)
124
F/U > 1 month
76.5%

4. Method The patients were divided into two groups according to age
Group A
Age < 50 yrs
Group B
Age ≥ 50 yrs n 29 95
Mean age (yrs)
42.9 ± 5.5
63.8 ± 7.4

5. Study design - Pre/Post op CT -① ③ ② ① ③ ②

6. Method
Dimensions of the index remnant aorta were analyzed and compared between the two groups after ascending/hemiarch aortic replacement for acute type A aortic dissection

7. Image analysis
One observer (JK) blinded to patient-identifying information performed the image analysis
The diameter of the remnant aorta at the aortic sinus, arch and the proximal descending thoracic aorta level were serially measured with chest CT images

8. Patient demographics and clinical characteristics
Group A
(n = 29)
Group B
(n = 95) P
value
Age (y)
42.9 ± 5.5
63.8 ± 7.4 NA
Male gender
18 (62.1)
38 (40.0)
.037
Risk Factors DM
1 (3.4)
3 (3.2)
> .999
Hypertension
10 (34.5)
58 (61.1)
.012
COPD
0 (0.0)
2 (2.1)
Renal failure
1 (1.1)
CVD
5 (5.3)
Marfan syndrome
3 (10.3)
.040
Bicuspid aortic valve
2 (6.9)
.136
COPD, Chronic obstructive pulmonary disease; CVD, cerebrovascular disease; DM, diabetes mellitus; IMH, intramural hematoma; NA, Not applicable.
*Chi-square statistic for overall difference.

9. Patient demographics and clinical characteristics
Group A
(n = 29)
Group B
(n = 95) P
value
Dissection Characteristics
.158*
DeBakey I
29 (100.0)
84 (88.4)
.066
DeBakey II
0 (0.0)
2 (2.1)
> .999
IMH (All DeBakey I)
9 (9.5)
.115
Malperfusion
Cerebral
1 (3.4)
4 (4.2)
Visceral
1 (1.1)
.415
Peripheral
2 (6.9)
5 (5.3)
.665
Previous cardiac or aortic surgery
COPD, Chronic obstructive pulmonary disease; CVD, cerebrovascular disease; DM, diabetes mellitus; IMH, intramural hematoma; NA, Not applicable.
*Chi-square statistic for overall difference.

10. Operative data Variable Group A (n = 29) Group B (n = 95) P value
Tear site location
.007*
Ascending aorta
14 (48.3)
53 (55.8)
.477
Aortic arch
3 (10.3)
16 (16.8)
.559
Descending thoracic aorta
2 (6.9)
4 (4.2)
.624
Combined
4 (13.8)
5 (5.3)
.212
Unidentified or unrecorded
6 (20.7)
17 (17.9)
.735
Tear site exclusion
18 (62.1)
74 (77.9)
.088
Aorta replacement
.771*
Ascending
5 (17.2)
14 (14.7)
.771
Ascending+hemiarch
24 (82.8)
81 (85.3)
ACC, Aortic cross-clamp; ACP, antegrade cerebral perfusion; AVP, aortic valvuloplasty; CABG, coronary artery bypass grafting; CPB, cardiopulmonary bypass; Fem-fem bypass, femorofemoral bypass grafting; RCP, retrograde cerebral perfusion; TCA, total circulatory arrest
*Chi-square statistic for overall difference.

11. Operative data Variable Group A (n = 29) Group B (n = 95) P value
Concomitant surgery
.931*
AVP
4 (13.8)
16 (16.8)
> .999
CABG
2 (6.9)
3 (3.2)
.665
Fem-fem bypass
1 (3.4)
4 (4.2)
Others
0 (0.0)
Cardiopulmonary bypass
CPB time (min)
218.9 ± 86.1
213.7 ± 88.8
.780
ACC time (min)
103.7 ± 56.2
106.9 ± 57.1
.794
Low body arrest time (min)
25.0 ± 12.0
28.3 ± 13.2
.305
TCA
0 (0)
6 (6.3)
.334
RCP
17 (58.6)
49 (51.6)
.506
ACP
12 (41.4)
40 (42.1)
.945
Target temperature (℃)
18.1 ± 4.5
18.2 ± 4.3
.917
ACC, Aortic cross-clamp; ACP, antegrade cerebral perfusion; AVP, aortic valvuloplasty; CABG, coronary artery bypass grafting; CPB, cardiopulmonary bypass; Fem-fem bypass, femorofemoral bypass grafting; RCP, retrograde cerebral perfusion; TCA, total circulatory arrest
*Chi-square statistic for overall difference.

12. Early outcomes and complications
Variable
Group A
(n = 29)
Group B
(n = 95) P
value
Neurologic deficits
2 (6.9)
6 (6.3)
>.999
Pneumonia
4 (13.8)
13 (13.7)
Renal failure
3 (10.3)
22 (23.2)
.132
Duration of mechanical ventilation (d)
2.6 ± 2.1
3.9 ± 7.4
.324
ICU stay (d)
5.6 ± 4.5
7.4 ± 9.1
.321
Hospital stay (d)
16.4 ± 9.5
26.7 ± 30.0
.005
In-hospital mortality
1 (3.4)
1 (1.1)
.415
Aortic reoperation
5 (5.3)
.388*
Root remodeling
0 (0.0)
Bentall operation
Replacement of total arch
Replacement of DTA
Replacement of TAA
Replacement of total arch and TAA
DTA, Descending thoracic aorta; ICU, intensive care unit; TAA, thoracoabdominal aorta.
*Chi-square statistic for overall difference.

13. CT follow up period Overall CT follow up period Young age Old age
Median: 36.4 (IQR 14.3 – 66.1) months
Young age
Median: 33.4 (IQR ) months
Old age
Median: 27.7 (IQR 6.3 – 54.8) months
Mean 53.4 ± 40.9 vs 40.8 ± 32.3 P =.088

14. Size changes of the remnant aorta on the computed tomography scans (mm)
Group A (n = 29)
Location
Group B (n = 95)
Preoperative
CT scan
Latest P
value
41.8 ± 6.0
44.1 ± 7.3
.004
Aortic sinus
40.5 ± 6.0
41.0 ± 5.4
.370
36.5 ± 6.8
41.3 ± 8.6
.010
Aortic arch
38.5 ± 5.0
37.6 ± 8.1
.380
36.4 ± 6.6
43.0 ± 11.2
.003
Proximal DTA
37.6 ± 4.8
40.6 ± 9.3
.002
CT, Computed tomography; DTA, descending thoracic aorta.

15. Size changes of the remnant aorta on the computed tomography scans (mm)
Location
Group A (n = 29)
Group B (n = 95)
P value
Preoperative
CT scan
Aortic sinus
41.8 ± 6.0
40.5 ± 6.0
.317
Aortic arch
36.5 ± 6.8
38.5 ± 5.0
.101
Proximal DTA
36.4 ± 6.6
37.6 ± 4.8
.295
Latest CT scan
44.1 ± 7.3
41.0 ± 5.4
.039
41.3 ± 8.6
37.6 ± 8.1
.037
43.0 ± 11.2 
40.6 ± 9.3
.253
CT, Computed tomography; DTA, descending thoracic aorta.

16. Impact of age on late aortic expansion determined by linear regression analyses
Unadjusted
Adjusted* R2
Beta
coefficient
Standard error P
value**
Standard
error
Aortic sinus
0.072
-0.064
0.038
0.098 (0.092)
0.225
-0.079
0.035
0.026 (0.020)
Aortic arch
0.058
-0.159
0.078
0.042 (0.028)
0.296
-0.120
0.068
0.079 (0.070)
Proximal DTA
0.073
-0.114
0.075
0.135 (0.101)
0.102
0.009
0.907 (0.892)
DTA, descending thoracic aorta.
*Multivariable linear regression analyses were performed. Covariates for multivariable models in addition to age were as follows (selected from univariable analyses that had p values of less than 0.20): (1) Aortic sinus: preoperative sinus diameter, root involvement of aortic dissection; (2) Arch: preoperative arch diameter; (3) Descending aorta: preoperative descending aortic diameter, intramural hematoma and distal extent of aortic dissection.
** Statistical models were further validated by 1000 bootstrap samples (P values in parentheses).

17. Association between age and aortic expansion rates developed by linear regression models

18. Overall Survival Curves

19. Finding
All index segments of the non-operated remnant aorta in young patients showed significant dilatation over time after acute type A aortic dissection surgery whereas in the older patients only the descending thoracic aorta appeared to significantly dilate

20. Comments
The results suggested a more extensive pattern of aortic remodeling in relatively younger patients
This may be due to greater incidence of intrinsic systemic aortic tissue disease in younger patients and inherent less well defined risk factors unique to this age group category
Young patient에 대한 정확한 genetic study가 이루어 지지 않은 상태에서 수술을 하는 경우가 많으므로 이러한 환자에게는 older patient 보다 좀 더 aggressive한 initial surgical procedure를 고려 할 필요가 있다.
Reoperation이 operative mortality를 높인다고 되어 있지 않기 때문에 (expert center에서) 모든 젊은 acute dissection에서 root replacement및 arch replacement를 권유하는 것은
아니지만 일정 기준 이상의 크기 및 pathologic 변화를 보이는 young aged aorta에서는 좀더 aggressive한 surgery 가 합리적일 수 있다.

21. Limitations Retrospective study How young is young? Measurement error
F/U period – relatively short follow up
Etiology? Biopsy studies?

22. Conclusion
Aorta tends to dilate in a more extensive fashion in young patients after acute AD surgery
Extensive surgery should be performed on a need basis- albeit more proactively
Close and frequent monitoring
Optimal medical treatment should be ensured

23. Thank you for your attention

24. Q & A

25. Total arch replacement
Acute AD Type A
< 50 y/o (n=83)
≥ 50 y/o (n=188) P
value
Bentall procedure
16 (19.3)
3 (1.6)
<.001
Root remodelling
1 (1.2)
4 (2.1)
>.999
Total arch replacement
31 (37.3)
36 (19.1)
<.002
Jan Dec 2013

26. Cause of Death n Group A Cardiac tamponade 1 Unknown 2 Group B
Tracheostomy obstruction
Malignancy 3
Sepsis