Randomized On/Off Bypass trial (ROOBY)

Anthony A. Bavry, M.D., M.P.H., F.A.C.C.; Deepak L. Bhatt, M.D., F.A.C.C.



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

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

Drugs/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.


  • Coronary heart disease

  • Coronary heart disease / Angina pectoris

  • Coronary heart disease / Angina pectoris / Stable


  • CABG

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%

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

Patient Population

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

Patient Population

Patients undergoing elective or urgent CABG