1. Are all forms of total arterial revascularisation equal? A comparison of single versus bilateral internal thoracic artery grafting strategies. William Y. Shi 1, Philip A. Hayward 1,2, John A. Fuller 2, James Tatoulis 3, Alexander Rosalion 4 and Brian F. Buxton 1, 2 1 Department of Cardiac Surgery, Austin Hospital, Melbourne, AUSTRALIA 2 Victorian Heart Centre, Epworth Hospital, Melbourne, AUSTRALIA 3 Department of Cardiothoracic Surgery, Royal Melbourne Hospital, Melbourne, AUSTRALIA 4 Department of Cardiothoracic Surgery, St Vincent’s Hospital, Melbourne, AUSTRALIA

2. Conflicts and Disclosures No disclosures or conflict of interest

3. Introduction

4. Survival: matched pairs

5. All arterial conduit coronary surgery has many forms

6. Introduction Do these all yield the same survival benefit?

7. METHODS University of Melbourne Cardiac Surgery Database 8 Centres 23343 cases between 1977-2010 Data linkage with National Death Index

8. Data inclusion Isolated primary CABG Three-vessel disease and all arterial grafts 1 st January 1995 to 31 st December 2010 n = 2821 Censor date 30 th April 2013 Propensity-score matching Cox regression for interaction effect

9. BITA +/- RA N = 912 (32%) VS ITA + ≥1 RA N = 1909 (68%) Exclusions: Any saphenous vein Ulnar or gastroepiploic artery in situ RITA-RCA 9756 with 3VD 2821 with 3VD TAR

10. in situ BITA +/- RA N = 380 (42%) VS LITA + free RITA + ≥1 RA N = 532 (58%) 912 with BITA 1069 (LITA) and 953 (RITA) distal anastomoses

11. Methods: grafting strategy Single ITA – LITA and 1-2 RA – 1/20 LITA sequential – 1/6 RA sequential – Mean 1.9 +/-0.6 radial distals per patient Bilateral ITA – RITA 25% to LAD, 15% to diag, 40% to Cx, 24% to PDA/PLV – 1/20 RITA sequential – Mean 1.1+/-0.5 radial distals per patient

12. RESULTS

13. Pre-operative clinical profile VariableBITASITAp valueStd diff Age >70124 (14)844 (44)<0.001-31.4 Male830 (91)1441 (75)<0.00142.5 Time period 1995 - 2000463 (51)1033 (54)--6.7 2001 - 2005286 (31)614 (32)--1.7 2006 - 2010163 (18)262 (14)0.01411.4 Diabetes123 (13)573 (30)<0.001-40.9 Cerebrovasc dis49 (5)197 (10)<0.001-18.5 Periph Vasc Dis39 (4)182 (10)<0.001-20.8 Current smoker216 (24)359 (19)0.00311.9 COPD24 (3)88 (5)0.013-10.6` LV function 30-49%191(21)457 (24)--7.2 <30%19 (2)66 (3)--8.4 >50%667 (73)1316 (69)-5.0 Left main >60%178 (20)353 (18)0.542.6 2 distals 3 distals 4 distals 43 (5) 464 (51) 326 (36) 243 (13) 953 (50) 573 (30) <0.001 28.7 1.9 12.2

14. Propensity-score analysis Study groups: N = 591 matched pairs VS BITA ± RA N = 591 LITA + ≥ 1RA N = 591

15. VariableBITA (n=591)SITA (n=591)p valueStd diff Age <50 51-60 Age 61-70 Age 71-80 Age >81 72 (12) 163 (28) 240 (41) 102 (17) 14 (2) 69 (12) 167 (28) 227 (38) 108 (18) 20 (3) 0.79 1.6 -1.5 4.5 -2.7 -6.1 Male529 (89)524 (89)>0.990.5 Diabetes111 (19)108 (18)0.881.3 Cerebrovasc disease42 (7) >0.990.0 Periph Vasc disease30 (5)31 (5)>0.99-0.8 Current smoker135 (23)125 (21)0.414.1 COPD16 (3)21 (4)0.534.1` LV function 30-49%127 (21)124 (21)-1.2 <30%12 (2)17 (3)--5.5 >50%425 (72)417 (71)-1.4 Left main >60%107 (18)113 (19)0.66-2.6 2 distals 3 distals 4 distals 36 (6) 305 (52) 201 (34) 53 (9) 290 (49) 193 (33) 0.25 -10.9 5.1 2.9

16. VariableBITA (n=591)SITA (n=591)p valueStd diff Centre 1 2 3 4 5 6 7 276 118 17 79 65 35 1 264 113 21 84 65 44 0 0.46 0.20 0.03 0.13 0.11 0.06 0.002 5.8 3.0 -5.7 -3.5 0.0 -9.1 5.8 Surgeon 1 2 3 4 5 129(22) 92(16) 123(21) 28(5) 22(4) 134(23) 86(15) 92(16) 28(5) 21(4) 0.42 0.26 0.05 0.34 0.21 -2.0 2.8 13.6 0.0 0.9 Time period 1995 - 2000305 (52)303 (51)-0.7 2001 - 2005177 (30)190 (32)--4.8 2006 - 2010106 (18)96 (16)0.624.5

17. Survival of 591 matched pairs

18. Propensity-score analysis Study groups: N = 206 matched pairs VS In situ BITA +≥1RA N = 206 LITA + free RITA ±RA N = 206

19. Does in situ vs free RITA matter? Survival of 206 matched pairs

20. Free RITA vs RA for 2 nd arterial graft Study groups: N = 380 matched pairs VS LITA + ≥1RA N = 380 LITA + free RITA ±RA N = 380

21. Free RITA instead of RA as 2 nd arterial graft: survival of 380 matched pairs

22. Interaction effects Cox regression using propensity score Hazard Ratio95% lower95% upperp value SITA vs. BITA comparison All BITA vs SITA0.730.590.900.004 LITA+FRITA vs. SITA+RA0.780.601.000.048 Bilat insitu ITA vs. SITA+RA0.670.470.950.026 Bilateral ITA patients Bilat insitu vs. LITA+FRITA0.710.471.080.11

23. Limitations Retrospective non randomised database Multiple surgeons and institutions with hidden bias Propensity matched pairs more representative of BITA group than SITA group Survival an incomplete endpoint to measure therapeutic effect of coronary surgery

24. Conclusion There is a benefit in survival from use of bilateral ITA over single ITA even when all arterial grafts are used for triple vessel disease If there is an advantage of bilateral in situ ITA over LITA and free RITA, it is too small to be detected in a cohort of over 2800 cases from a database of 23000 patients – arguably may not be clinically significant in a decade of surgeon practice.

25. Conclusion There is a measurable impact on survival by use of bilateral ITA over single ITA even when all arterial grafts are used for triple vessel disease There is no significant survival benefit from bilateral in situ ITA over LITA + free RITA in our dataset