1. Configurations of Arterial Grafts : When to use a SV Graft
Joseph F. Sabik, MD
Chairman and Professor of Surgery
Department of Thoracic and Cardiovascular Surgery
Sheik Hamdam Bin Rashid Al Maktoum Distinguished Chair
Cleveland Clinic Lerner College of Medicine

2. When might a SV graft be better than an arterial graft ?

3. Graft Occlusion 1. Time  with time 2. Coronary Varies with coronary
3. Conduit
4. Patient
 with time
Varies with coronary
 ITA with  competitive flow
 with SVG
Age ♀ Diabetes
Using multivariable, longtitudinal repeated-measures analysis we identified four categories of factors associated with graft occlusion : Time, Coronary Artery, Conduit and Patient demographics.
Increasing time from CABG decreased patency of both ITA and SVGs . However, the rate of occlusion was much greater for SVGs than ITA grafts. ITA grafts to the LAD demonstrated stable patency over time, whereas ITA grafts bypassed to the other coronary arteries had a modest temporal decline in patency.
For both ITA grafts and SVGs, patency was highest when bypassing the LAD and lowest when bypassing the main RCA. Bypass grafts to diagonals, LCx, and PDA had similar patency.
Decreasing proximal coronary artery stenosis was associated with reduced ITA graft patency. However, SVG patency did not decrease with increasing competitive flow. Competitive flow only mildly reduced ITA patency when used to graft the LAD, but strongly decreased it when used to graft the RCA.
Saphenous vein grafts had lower patency than ita grafts
Female gender, young age, and diabetes were associated with increased graft occlusion.
Sabik, Ann Thorac Surg, 2005

4. Time LAD Grafts 100 80 Graft Patency 60 40 20
ITA
SVG 20
This slide shows the relationship between graft patency and years after surgery in coronary artery bypass grafts to the Left anterior descending coronary artery, in both diabetics and non-diabetics
The Solid yellow line represents internal thoracic artery graft patency in non-diabetics and the dotted yellow line represents internal thoracic artery graft patency in diabetics.
Simimarly, the Solid red line demonstrates Saphanous vein graft patency in non- diabetics and the dotted red line demonstrates Saphanous vein graft patency in diabetics.
Graft Patency was slightly less for both ITA and SVG in diabetics.
Internal thoracic artery grafts to the Left anterior descending coronary artery remains fairly stable from 1 to 15 years after coronary surgery. In non-diabetics internal thoracic artery patency to Left anterior descending coronary artery was 95% at 1 year, 93% at 10 years and 93% at 15 years, and in diabetics ITA graft patency was 93% at 1 years, 91% at 10 years and 90% at 15 years.
However, Saphenous vein grafts patency declined over time. SephanousVein Grafts patency to Left anterior descending coronary artery in non-diabetics was 84% at year, 48% at 10 year and 30% at 15 yearr, while in diabetics, it was 80 % at year, 42% at 10 year and 26% at 15 years. 2 4 6 8 10 12 14 16
Years from CABG
Sabik, Ann Thorac Surg, 2005

5. ITA Patency Coronary Grafted
100
ITA→Dg/Cx/PDA 80
ITA→RCA
ITA → LAD %
Patent
Grafts 60 40 20 2 4 6 8 10 12 14 16
Years after CABG
Sabik, Ann Thorac Surg, 2005

6. Competitive Flow ITA Patency % Proximal Stenosis (%) 100 LAD 80
Non-LAD 60 % 40 20
Last year, at this meeting we had the opportunity to present our findings of the effect of competitive flow on internal thoracic artery graft patency.
This slide summarizes those results.
Lesser degrees of proximal coronary stenosis are associated with decreased internal thoracic artery graft patency.
Due to this negative effect of competitive flow on ITA patency, the use of saphenous vein grafts has been advocated when bypassing coronary arteries with only moderate stenosis and important competitive flow. However, for SVG to be beneficial in these circumstances, SVG patency must be better. 40 50 60 70 80 90
100
Proximal Stenosis (%)
Sabik, Ann Thorac Surg, 2003

7. Competitive Flow and Time
ITA Patency to LAD
100 80 60
ITA Patency (%) 40
1 year
5 years
10 years
15 years 20
For internal thoracic artery grafts to the left anterior descending, patency did not decrease from 1 to 15 years after coronary surgery.
Internal thoracic artery patency for grafts to left anterior descending coronary arteries with 50% proximal stenosis was 92% one to fifteen years after surgery. For grafts to left anterior descending coronary arteries with 70% proximal stenosis, ITA patency was 95% one to fifteen years after surgery, and for grafts to totally occluded left anterior descending coronary arteries, ITA patency was 98% one to fifteen years after surgery. 40 50 60 70 80 90
100
Proximal Stenosis (%)
Sabik, Ann Thorac Surg, 2003

8. Competitive Flow and Time
ITA Patency to Non-LAD
100 80 60
ITA Patency (%) 40
1 year
5 years
10 years
15 years 20
For grafts to non-left anterior descending coronary arteries patency decreased progressively from 1 year, shown in yellow, to 15 years, shown in blue, after coronary grafting.
This decrease in patency with time was magnified in grafts to coronary arteries with lesser degrees of stenosis.
Internal thoracic artery graft patency to non – left anterior descending coronary arteries with 50% stenosis at 1 year was 91%, at ten years 83%, and at 15 years 76%.
In contrast, for totally occluded non-left anterior descending coronary arteries, internal thoracic artery graft patency at 1 year was 98%, at 10 years 96%, and at 15 years 93%. 40 50 60 70 80 90
100
Proximal Stenosis (%)
Sabik, Ann Thorac Surg, 2003

9. ITA versus SVG Time Conduit ITA SVG Coronary Which One
Competitive Flow

10. LAD Graft Patency 1 Yr % Proximal Stenosis (%) 100 ITA SVG 80 60 40 20
This slide, and several to follow, depict the relationship between proximal coronary artery stenosis, along the horizontal axis, and predicted internal thoracic artery patency, in yellow, and saphenous vein graft patency, in red, along the vertical axis.
This graft is for patency of ITA and SVG to the lad one year after surgery.
Internal thoracic artery graft patency decreases with decreasing coronary stenosis, while saphenous vein graft patency is unaffected by competitive flow.
However at all levels of clinical important coronary artery stenosis of the left anterior descending one year after surgery, internal thoracic artery patency is better than saphenous vein graft patency. 40 50 60 70 80 90
100
Proximal Stenosis (%)
Sabik, Ann Thorac Surg, 2005

11. LAD Graft Patency 10 Yrs ITA SVG % Proximal Stenosis (%) 100 80 60 4020
At ten years after surgery, internal thoracic artery graft patency continues to be better than saphenous vein graft patency at all degrees of important coronary stenosis, and the benefit of ITA grafting has increased.
This increase in the difference in internal thoracic artery graft and saphenous vein graft patency with time is due to the stability of internal thoracic arteries when used to bypass the left anterior descending, and the temporal decline in saphenous vein graft patency. 40 50 60 70 80 90
100
Proximal Stenosis (%)
Sabik, Ann Thorac Surg, 2005

12. Dg/Cx/PDA Graft Patency 1 Yr
100
ITA 80
SVG 60 % 40 20
At one year after surgery, internal thoracic artery grafts had better predicted patency than saphenous vein grafts at all degrees of clinically important proximal coronary artery stenosis when used to graft diagonal, circumflex, and posterior descending coronary arteries. 40 50 60 70 80 90
100
Proximal Stenosis (%)
Sabik, Ann Thorac Surg, 2005

13. Dg/Cx/PDA Graft Patency 10 Yrs
100
ITA 80 60
SVG % 40 20
The difference between internal thoracic artery patency and saphenous vein graft patency when used to bypass diagonal, circumflex, and posterior descending coronary arteries also increased with time.
This is due to the much faster rate of saphenous vein graft occlusion. 40 50 60 70 80 90
100
Proximal Stenosis (%)
Sabik, Ann Thorac Surg, 2005

14. RCA Graft Patency 1 Yr ITA SVG % Proximal Stenosis (%) 100 80 60 40 20
For the right coronary artery, patency one year after surgery of internal thoracic artery grafts is only better than the patency of saphenous vein grafts when used to bypass arteries with severe stenosis or occlusion.
At one year after surgery, saphenous vein graft patency was better when grafting right coronary arteries with moderate stenosis.
This is due to the strong negative influence of competitive flow on ITA grafts when bypassing the right coronary artery. 40 50 60 70 80 90
100
Proximal Stenosis (%)
Sabik, Ann Thorac Surg, 2005

15. RCA Graft Patency 10 Yrs ITA SVG % Proximal Stenosis (%) 100 80 60 4020
However, by ten years after surgery, when used to bypass the right coronary artery, internal thoracic arteries are m6re likely to be patent than saphenous vein grafts at all levels of important stenosis.
This is due to the much faster rate of saphenous vein graft occlusion with time. 40 50 60 70 80 90
100
Proximal Stenosis (%)
Sabik, Ann Thorac Surg, 2005

16. ITA versus SVG Patency ITA grafts always better than SVG to LAD Dg Cx
PDA
SVG better than ITA grafts to
RCA, moderate stenosis
By 10 years, ITA better
At all times after operation and at all degrees of proximal coronary artery stenosis, ITA grafts were more likely to be patent than SVGs when used to bypass the LAD, diagonals, LCx, and PDA.
Early after CABG, SVGs demonstrated better patency when used to bypass moderately stenosed main RCAs.
However, because of SVG atherosclerosis, by 10 years postoperatively, ITA grafts are more likely than SVGs to be patent to even moderately stenosed RCAs.

17. Vein Graft Patency Rates are (Likely) Better Today
Platelets inhibitors
Statins

18. Dipyridamol Pre-op ASA postop
Vein Graft Occlusion
Dipyridamol Pre-op ASA postop
1 week
1 year
Placebo 10% 25%
Drug 2% 11%
Chesbro et. Al NEJM (1984)

19. Vein Graft Atherosclerosis
Lovastatin - Cholastyramine
Lower LDL Cholesterol
Moderate
LDL
Aggressive
LDL
Progression of Death 39% 27% <0.001
Grafts with Progression 35% % < Occlusion 11% 6% < New Lesions 21% 10% < Improvement 4% 5% <0.52
Post CABG Trial NEJM 1997

20. Saphenous Vein Grafts Opportunities
Better Platelet Inhibition
Cascade
Aggressive Lipid Reduction
Prevention of Vein Graft Injury
Harvesting
Distension

21. Saphenous Vein Support Technology
eSVSTM + vein
Saphenous Vein Support Technology
Investigational use only under USA law. 21

22. 180 Days Sheep Pathology/Histology
All sheep were sacrificed at 180 days.
You can see how clear the vein with mesh is compared to the control vein. 22

23. IVUS eSVS and Control SVG 14 mths Post Implant
Control Vein LCX
eSVS Vein RCA

24. Summary
SV Grafts better when used to graft right coronary arteries with moderate stenosis
SV Grafts likely better today