Are all forms of total arterial revascularisation equal? A comparison of single versus bilateral internal thoracic artery grafting strategies.

William Y. Shi1, Philip A. Hayward1,2, John A. Fuller2,

James Tatoulis3, Alexander Rosalion4 and Brian F. Buxton1, 2

1 Department of Cardiac Surgery, Austin Hospital, Melbourne, AUSTRALIA2 Victorian Heart Centre, Epworth Hospital, Melbourne, AUSTRALIA3 Department of Cardiothoracic Surgery, Royal Melbourne Hospital, Melbourne, AUSTRALIA4 Department of Cardiothoracic Surgery, St Vincent’s Hospital, Melbourne, AUSTRALIA

Conflicts and Disclosures

No disclosures or conflict of interest

Introduction

Survival: matched pairs

All arterial conduit coronary surgery has many forms

Introduction

Do these all yield the same survival benefit?

METHODS

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

Data inclusion

• Isolated primary CABG• Three-vessel disease and all arterial grafts• 1st January 1995 to 31st December 2010

• n = 2821

• Censor date 30th April 2013• Propensity-score matching• Cox regression for interaction effect

BITA +/- RA

N = 9 12 (32%) VSITA + ≥1 RA

N = 1909 (68%)

Exclusions:Any saphenous vein

Ulnar or gastroepiploic artery in situ RITA-RCA

9756 with 3VD

2821 with 3VD TAR

in situ BITA +/- RA

N = 380 (42%) VSLITA + free RITA + ≥1 RA

N = 532 (58%)

912 with BITA

1069 (LITA) and 953 (RITA) distal anastomoses

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

RESULTS

Pre-operative clinical profileVariable BITA SITA p value Std diff

Age >70 124 (14) 844 (44) <0.001 -31.4 Male 830 (91) 1441 (75) <0.001 42.5Time period

1995 - 2000 463 (51) 1033 (54) - -6.72001 - 2005 286 (31) 614 (32) - -1.72006 - 2010 163 (18) 262 (14) 0.014 11.4

Diabetes 123 (13) 573 (30) <0.001 -40.9Cerebrovasc dis 49 (5) 197 (10) <0.001 -18.5Periph Vasc Dis 39 (4) 182 (10) <0.001 -20.8Current smoker 216 (24) 359 (19) 0.003 11.9COPD 24 (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) 0.54 2.62 distals3 distals4 distals

43 (5)464 (51)326 (36)

243 (13)953 (50)573 (30)

<0.00128.71.9

12.2

Propensity-score analysis• Study groups:

N = 591 matched pairs

VSBITA ± RA

N = 591

LITA + ≥ 1RAN = 591

Variable BITA (n=591) SITA (n=591) p value Std diff

Age <5051-60Age 61-70Age 71-80Age >81

72 (12)163 (28)240 (41)102 (17)

14 (2)

69 (12)167 (28)227 (38)108 (18)

20 (3)

0.79

1.6-1.54.5-2.7-6.1

Male 529 (89) 524 (89) >0.99 0.5Diabetes 111 (19) 108 (18) 0.88 1.3Cerebrovasc disease 42 (7) 42 (7) >0.99 0.0Periph Vasc disease 30 (5) 31 (5) >0.99 -0.8Current smoker 135 (23) 125 (21) 0.41 4.1COPD 16 (3) 21 (4) 0.53 4.1`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 distals3 distals4 distals

36 (6)305 (52)201 (34)

53 (9)290 (49)193 (33)

0.25-10.95.12.9

Variable BITA (n=591) SITA (n=591) p value Std diff

Centre 1 2 3 4 5 6 7

276118177965351

264113218465440

0.460.200.030.130.110.06

0.002

5.83.0-5.7-3.50.0-9.15.8

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)

0.420.260.050.340.21

-2.02.8

13.60.00.9

Time period

1995 - 2000 305 (52) 303 (51) - 0.72001 - 2005 177 (30) 190 (32) - -4.8

2006 - 2010 106 (18) 96 (16) 0.62 4.5

Survival of 591 matched pairs

Propensity-score analysis• Study groups:

N = 206 matched pairs

VSIn situ BITA +≥1RA

N = 206

LITA + free RITA ±RAN = 206

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

Free RITA vs RA for 2nd arterial graft• Study groups:

N = 380 matched pairs

VSLITA + ≥1RAN = 380

LITA + free RITA ±RAN = 380

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

Interaction effectsCox regression using propensity score

Hazard Ratio 95% lower 95% upper p value

SITA vs. BITA comparison

All BITA vs SITA 0.73 0.59 0.90 0.004

LITA+FRITA vs. SITA+RA 0.78 0.60 1.00 0.048

Bilat insitu ITA vs. SITA+RA 0.67 0.47 0.95 0.026

Bilateral ITA patients

Bilat insitu vs. LITA+FRITA 0.71 0.47 1.08 0.11

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

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.

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

Thank you