Randomized On/Off Bypass trial - ROOBY


The goal of the trial was to evaluate coronary artery revascularization with off-pump compared with on-pump coronary artery bypass grafting (CABG).


Off-pump CABG would be associated with similar outcomes as on-pump procedures.

Study Design

  • Randomized
  • Parallel

Patients Screened: 9,663
Patients Enrolled: 2,203
Mean Follow Up: 1 year
Mean Patient Age: 63 years
Female: <1
Mean Ejection Fraction: 58% of participants had an ejection fraction >54%

Patient Populations:

  • Patients undergoing elective or urgent CABG


  • Significant valve disease
  • Need for immediate surgery
  • Small target vessels
  • Diffuse coronary artery disease
  • Patients with high-risk for adverse events
  • Inability of the patient to provide informed consent

Primary Endpoints:

  • Primary short-term outcome within 30 days: composite of death or major complications (reoperation, new mechanical support, cardiac arrest, coma, stroke, or renal failure requiring dialysis)
  • Primary long-term outcome within 1 year: composite of death, nonfatal myocardial infarction, or repeat revascularization

Secondary Endpoints:

  • Completeness of revascularization
  • Graft patency at 1 year
  • Neuropsychological testing

Drug/Procedures Used:

Patients scheduled for elective or urgent CABG were randomized to off-pump (n = 1,104) versus on-pump (n = 1,099) procedures.

Principal Findings:

Overall, 2,203 patients were randomized. There was no difference in baseline characteristics between the groups. In the off-pump group, the mean age was 63 years, 0.6% were women, 84% were Caucasian, 0.8% had previous CABG, 16% had peripheral arterial disease, 59% had an ejection fraction >54%, 33% were current smokers, and the estimated risk of death before discharge or 30 days was 1.9%.

The off-pump group received 2.9 grafts per patient, while the on-pump group received 3.0 grafts per patient (p = 0.002). Transfusion was needed in 52% versus 56% (p = 0.05), hours in the operating room were 4.5 versus 4.4 (p = 0.05), and length of stay in the hospital was 8.2 days versus 7.8 days (p = 0.22), respectively for off-pump versus on-pump.

The primary short-term composite outcome occurred in 7.0% of the off-pump versus 5.6% of the on-pump group (p = 0.19), while the primary long-term composite outcome occurred in 9.9% versus 7.4% (p = 0.04), respectively. Death within 30 days was 1.6% versus 1.2% (p = 0.47), all-cause death within 1 year was 4.1% versus 2.9% (p = 0.15), and cardiac death within 1 year was 2.7% versus 1.3% (p = 0.03), respectively for off-pump versus on-pump. Neuropsychological outcomes were similar between the groups.

Overall graft patency was 82.6% versus 87.8% (p < 0.001), saphenous vein graft patency was 76.6% versus 83.8% (p < 0.001), and at least one occluded graft was 36.5% versus 28.7% (p = 0.002), respectively for off-pump versus on-pump.


Among patients undergoing elective or urgent CABG, the use of off-pump procedures does not result in similar clinical outcomes as on-pump procedures. Off-pump CABG was associated with worse outcomes, including higher cardiac death and lower graft patency at 1 year. Off-pump patients also received slightly fewer grafts (2.9 vs. 3.0). Outcomes were the same when analyzed according to high-volume or low-volume surgeons. Cognitive function appeared to be similar in both groups. It is possible that worse long-term clinical outcomes with off-pump procedures may be due to a lower rate of graft patency.

This study does not provide any insight into the preferred surgical approach in women, so further study is needed.


Shroyer AL, Grover FL, Hattler B, et al. On-pump versus off-pump coronary-artery bypass surgery. N Engl J Med 2009;361:1827-37.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Stable Ischemic Heart Disease, Vascular Medicine, Atherosclerotic Disease (CAD/PAD), Cardiac Surgery and SIHD, Interventions and Coronary Artery Disease, Interventions and Vascular Medicine, Chronic Angina

Keywords: Cognition, Coronary Artery Disease, Angina, Stable, Saphenous Vein, Peripheral Arterial Disease, Coronary Artery Bypass, Length of Stay

< Back to Listings