Resident versus Attending Surgeon Patency and Clinical Outcomes in On- versus Off-Pump Coronary Artery Bypass Surgery

G Hossein Almassi, MD1

Brendan M. Carr, MS2

Muath Bishawi, MD, MPH3

A. Laurie Shroyer, PhD2

Jacquelyn A. Quin, MD4

Brack Hattler, MD5

Todd H. Wagner, PhD6

Joseph F. Collins, PhD7

Pasala Ravichandran, MD8

Joseph C. Cleveland, MD9

Frederick L. Grover, MD5,9

Faisal G. Bakaeen, MD10

for the VA #517 Randomized On/Off Bypass (ROOBY) Study Group

1Cardiothoracic Surgery, Medical College of Wisconsin and Veterans Affairs (VA) Medical Center, Milwaukee, WI; 2Surgery, Northport VA Medical Center and Stony Brook Medicine School of Medicine, Stony Brook, NY; 3Surgery, Duke University, Durham, NC; 4Cardiac Surgery, VA Boston Healthcare System, West Roxbury, MA; 5Cardiology, VA Eastern Colorado Health Care System, Denver, CO; 6VA Palo Alto Health Economics Resource Center, Menlo Park, CA and Department of Health Research and Policy, Stanford University, Stanford, CA; 7Cooperative Studies Program Coordinating Center and VA Medical Center, Perry Point, Maryland; 8Surgery, Oregon Health and Sciences University and Portland VA Medical Center, Portland, OR; 9Surgery, University of Colorado School of Medicine at the Anschutz Medical Campus, Aurora, CO; 10Cardiothoracic Surgery, Baylor College of Medicine and Houston VA Medical Center, Houston, TX

Presenter Disclosure

No disclosure to report

Funding

Cooperative Studies Program of the Department of Veterans Affairs Office of Research and Development and the Department of Veterans Affairs Central Office, Office of Patient Care Services.

Offices of Research and Development at the Zablocki VA Medical Center, Northport VA Medical Center, and the VA Eastern Colorado Healthcare System.

Background

Residents must be trained to perform cardiac surgical procedures

Balance between education and what is best for the patient

Prior studies have shown no impact on CABG clinical outcomes

Little information about effect on graft patency

Background

Bakaeen et al., 2012 – residents and attendings had similar outcomes and 1-year patency

Bakaeen et al., 2009 – residents had longer operative times, perfusion and cross-clamp times, but similar outcomes

Guo et al., 2008 – residents /fellows vs. consultants had similar operative morbidity and mortality in on-pump CABG

Background

Haan et al., 2007 – hospitals with residency programs have longer perfusion times but similar outcomes

Asimakopoulos et al., 2006 – residents had similar operative morbidity and mortality in off-pump CABG

Ascione et al., 2004 – residents had similar morbidity and mortality in high-risk off-pump CABG patients

Research Questions

Do different clinical outcomes result when residents vs. attendings perform the majority of distal coronary anastomoses?

Do grafts performed during CABG by residents vs. attendings have different rates of patency at 1 year postop?

Are these results different for on-pump vs. off-pump CABG?

ROOBY Trial

VA Cooperative Study (18 centers) February 2002 – May 2008 Prospective, randomized, single-blinded Comparison of CABG with and without CPB

ONCAB (n = 1,099) OPCAB (n = 1,104) Total (n = 2,203)

Study Population

All patients = 1,272 16 centers with cardiac surgery residents Data on resident anastomoses captured

beginning July 2003

OPCAB = 639 Patients Resident as primary surgeon: 431 (67.4%)

ONCAB = 633 Patients Resident as primary surgeon: 493 (77.9%)

Definition

Primary surgeon: The individual (resident or attending) who

performed ≥ 50% of the distal anastomoses in a given patient

Clinical Outcomes

Short-term (30-day) composite endpoint: Death Reoperation New mechanical support Cardiac arrest Coma Stroke Renal failure requiring dialysis

1-year composite endpoint: Death from any cause within 1 year after surgery Nonfatal myocardial infarction between 30 days and 1 year Any revascularization procedure between 30 days and 1 year

Graft Patency

Coronary angiography at 1 year postop

FitzGibbon classification A = An excellent/unimpaired graft B = An impaired graft with a stenosis >50%

reducing the caliber of the graft to <50% of the target artery diameter

O = A completely occluded graft

Statistical Methods

Discrete variables: Chi-square or Fisher Exact tests

Continuous variables: Student T-tests

Multivariate Regression

Significance at p < 0.01 for all ROOBY sub-studies

Results

Baseline patient characteristicsPatient risk profile On-pump

N=633Off-pump

N=639

Residentn/N (%)

Attendingn/N (%)

p-value Residentn/N (%)

Attendingn/N (%)

p-value

COPD 119/493 (24.1) 20/140 (14.3) 0.013 89/431 (20.6) 44/208 (21.2) 0.88

Creatinine > 1.5 mg/dl 30/493 (6.1) 14/140 (10.0) 0.11 38/431 (8.8) 17/208 (8.2) 0.79

Cerebrovascular accident 31/493 (6.3) 13/140 (9.3) 0.22 26/431 (6.0) 14/208 (6.7) 0.73

Peripheral artery disease 61/493 (12.4) 18/140 (12.9) 0.88 65/431 (15.1) 40/208 (19.2) 0.18

Diabetes 233/493 (47.3) 63/140 (45.0) 0.64 202/431 (46.9) 82/208 (39.4) 0.08

Hypertension 424/493 (86.0) 128/140 (91.4) 0.09 374/431 (86.8) 180/208 (86.5) 0.93

Atrial fibrillation 10/493 (2.0) 2/140 (1.4) 0.65 14/429 (3.3) 11/208 (5.3) 0.22

LVEF by category< 35%≥ 35%

 23/485 (4.7)

462/485 (95.3)

 5/132 (3.8)

127/132 (96.2)

0.64  19/419 (4.5)

400/419 (95.5)

 17/201 (8.5)

184/201 (91.5)

0.05

Prior MI 142/490 (29.0) 39/138 (28.3) 0.87 116/427 (27.2) 63/208 (30.3) 0.41

β-Blocker Use 302/493 (61.3) 83/140 (59.3) 0.67 275/431 (63.8) 127/208 (61.1) 0.50

Aspirin 411/493 (83.4) 119/140 (85.0) 0.64 370/431 (85.8) 168/208 (80.8) 0.10

Urgent case 60/493 (12.2) 16/140 (11.4) 0.81 62/431 (14.4) 27/208 (13.0) 0.63

*NOTE: p-value is for the comparison between treatment groups

 

Coronary anatomyOn-pump

N=633Off-pump

N=639

Residentn/N (%)

Attendingn/N (%)

p-value Residentn/N (%)

Attendingn/N (%)

p-value

Territories with disease

123

 

34/493 (6.9)133/493 (27.0)322/493 (65.3)

 

9/140 (6.4)31/140 (22.1)

100/140 (71.4)

0.43

 

34/431 (7.9)132/431 (30.6)263/431 (61.0)

 

11/207 (5.3)61/207 (29.5)

132/207 (63.8)

0.35

Distals performed by

Resident onlyAttending onlyBoth

 

303/633 (47.9)121/633 (19.1)209/633 (33.0)

   

269/639 (42.1)168/639 (26.3)202/639 (31.6)

0.008*

Coronary territories and anastomoses per primary surgeon

  On-pumpn/N (%) OR mean ± SD

Off-pumpn/N (%) OR mean ± SD

  Resident Attending p-value

Resident Attending p-value

LAD anastomosesQuality of target

Good/ModeratePoor

 450/482 (93.4)

32/482 (6.6)

 118/136 (86.8)18/136 (13.2)

0.01 

414/443 (93.5)29/443 (6.5)

 159/179 (88.8)20/179 (11.2)

0.05

Diagonal anastomosesQuality of target

Good/ModeratePoor

 164/176 (93.2)

12/176 (6.8)

 48/51 (94.1)

3/51 (5.9)0.81

 114/129 (88.4)15/129 (11.6)

 62/69 (89.9)7/69 (10.1)

0.75

Circumflex (AV) / OM anastomosesQuality of target

Good/ModeratePoor

 304/331 (91.8)

27/331 (8.2)

 130/145 (89.7)15/145 (10.3)

0.44 

207/227 (91.2)20/227 (8.8)

 196/211 (92.9)

15/211 (7.1)0.51

Ramus anastomosesQuality of target

Good/ModeratePoor

 40/45 (88.9)5/45 (11.1)

 15/18 (83.3)3/18 (16.7)

0.55 

40/41 (97.6)1/41 (2.4)

 28/30 (93.3)

2/30 (6.7)0.38

Right main coronary anastomosesQuality of target

Good/ModeratePoor

 43/47 (91.5)

4/47 (8.5)

 36/40 (90.0)4/40 (10.0)

0.81 

56/59 (94.9)3/59 (5.1)

 46/52 (88.5)6/52 (11.5)

0.21

PDA anastomosesQuality of target

Good/ModeratePoor

 134/156 (85.9)22/156 (14.1)

 126/151 (83.4)25/151 (16.6)

0.55 

113/127 (89.0)14/127 (11.0)

 130/142 (91.5)

12/142 (8.5)0.48

Posterolateral anastomosesQuality of target

Good/ModeratePoor

 21/23 (91.3)

2/23 (8.7)

 14/18 (77.8)4/18 (22.2)

0.22  14/14 (100.0)

0/14 (0.0)

 17/18 (94.4)

1/18 (5.6)

0.37

Comparison of target vessels quality based on who actually performed the anastomoses

Operative variables by primary surgeon

Patients operative profile

On-pumpN=633

Off-pumpN=639

Residentn/N (%)

Attendingn/N (%)

p-value Residentn/N (%)

Attendingn/N (%)

p-value

Units of packed RBC 1.0 ± 1.6 (n=493)

0.9 ± 1.6 (n=140)

0.89 1.0 ± 1.5 (n=430)

1.0 ± 1.6 (n=208)

0.65

Units of fresh frozen plasma

0.4 ± 1.1 (n=493)

0.5 ± 1.4 (n=140)

0.51 0.5 ± 1.3 (n=430)

0.5 ± 1.3 (n=208)

0.73

Units of platelets 0.3 ± 1.5 (n=493)

0.1 ± 0.6 (n=140)

0.03 0.4 ± 1.7 (n=430)

0.4 ± 1.5 (n=208)

0.96

Take down and redo of distal

14/493 (2.8) 6/140 (4.3) 0.39 17/431 (3.9) 5/208 (2.4) 0.32

Short-term Clinical Outcomes

* Short-term composite endpoint included death, reoperation, new mechanical support, cardiac arrest,

coma, stroke, or renal failure requiring dialysis before discharge or within 30 days after surgery

  On-pumpn/N (%) OR mean ± SD

Off-pumpn/N (%) OR mean ± SD

  Resident Attending p-value Resident Attending p-value

Short-term composite* 24/493 (4.9) 10/140 (7.1) 0.29 27/431 (6.3) 10/208 (4.8) 0.46

Reoperation for bleeding 9/493 (1.8) 4/140 (2.9) 0.45 14/431 (3.2) 4/208 (1.9) 0.34

Stroke 3/493 (0.6) 2/140 (1.4) 0.33 3/431 (0.7) 2/208 (1.0) 0.72

Renal failure requiring dialysis

2/493 (0.4) 0/140 (0.0) 0.45 3/431 (0.7) 2/208 (1.0) 0.72

Prolonged vent >48hrs 15/493 (3.0) 6/140 (4.3) 0.47 21/431 (4.9) 9/208 (4.3) 0.76

Re-intubation 13/493 (2.6) 5/140 (3.6) 0.56 16/429 (3.7) 5/208 (2.4) 0.38

MI 18/493 (3.7) 4/140 (2.9) 0.65 25/431 (5.8) 12/208 (5.8) 0.99

New mechanical sup. 5/493 (1.0) 1/140 (0.7) 0.75 5/431 (1.2) 4/208 (1.9) 0.44

Mediastinitis 4/493 (0.8) 4/140 (2.9) 0.06 3/431 (0.7) 5/208 (2.4) 0.07

Operative Death 3/493 (0.6) 2/140 (1.4) 0.33 5/431 (1.2) 1/208 (0.5) 0.40

Hospital length of stay (days)

7.6 ± 5.3(n=486)

8.1 ± 6.8(n=139)

0.43 7.6 ± 4.4(n=425)

7.9 ± 5.6(n=203)

0.53

1-Year Clinical Outcomes  On-pump

n/N (%) OR mean ± SD (n)Off-pump

n/N (%) OR mean ± SD (n)

  Resident Attending p-value Resident Attending p-value

1-year composite* 32/493 (6.5) 8/140 (5.7) 0.74 44/431 (10.2) 19/208 (9.1) 0.67

All-cause death 12/493 (2.4) 4/140 (2.9) 0.78 17/431 (3.9) 5/208 (2.4) 0.32

Repeat revascularization†

16/493 (3.2) 4/140 (2.9) 0.82 25/431 (5.8) 11/208 (5.3) 0.79

Non-fatal MI† 8/493 (1.6) 2/140 (1.4) 0.87 5/431 (1.2) 4/208 (1.9) 0.44

*1-year composite endpoint included death from any cause within 1 year after surgery, nonfatal myocardial infarction between 30 days and 1 year, and any revascularization procedure between 30 days and 1 year † These two late adverse outcomes were evaluated from the time of 30-days post-surgery up until 1-year follow-up

  On-pump Off-pump

  Residentn/N (%)

Attendingn/N (%)

p-value Residentn/N (%)

Attendingn/N (%)

p-value

OverallABO

 590/711 (83.0)

23/711 (3.2)98/711 (13.8)

 262/318 (82.4)

8/318 (2.5)48/318 (15.1)

0.72  491/636 (77.2)

27/636 (4.2)118/636 (18.6)

 328/428 (76.6)

20/428 (4.7)80/428 (18.7)

0.94

SVGABO

 314/414 (75.8)

15/414 (3.6)85/414 (20.5)

 178/228 (78.1)

8/228 (3.5)42/228 (18.4)

0.81  260/369 (70.5)

12/369 (3.3)97/369 (26.3)

 213/294 (72.4)

13/294 (4.4)68/294 (23.1)

0.51

LIMAABO

 253/268 (94.4)

6/268 (2.2)9/268 (3.4)

 71/74 (95.9)

0/74 (0.0)3/74 (4.1)

0.42  219/247 (88.7)

14/247 (5.7)14/247 (5.7)

 99/112 (88.4)

5/112 (4.5)8/112 (7.1)

0.78

1-Year FitzGibbon Patency

A = An excellent/unimpaired graftB = An impaired graft with a stenosis >50% reducing the caliber of the graft to <50% of the target artery diameterO = A completely occluded graft

SVG = Saphenous vein graftLIMA = Left internal mammary artery

Limitations

Attendings could have assisted residents in ways not documented

Predominantly male veteran population Subgroup analysis Resident anastomosis data not captured

during first year of ROOBY trial Follow-up limited to 1 year

Conclusions

For ROOBY Trial patients: No difference in perioperative

outcomes No difference in 1-year outcomes No difference in 1-year graft

patency

Conclusion

Residents can and should be trained in advanced surgical techniques with no negative impact on surgical outcomes.

Thank You