Best Bypass Surgery trial - BBS

Description:

The goal of the trial was to evaluate coronary artery bypass graft surgery (CABG) performed off-pump versus on-pump in patients with coronary artery disease.

Hypothesis:

Off-pump CABG would be associated with improved adverse outcomes in high-risk patients.

Study Design

  • Randomized
  • Blinded
  • Parallel
  • Stratified

Patients Screened: 2,578
Patients Enrolled: 341
NYHA Class: NYHA class III or IV: 29%
Mean Follow Up: 30 days
Mean Patient Age: 76 years
Female: 35
Mean Ejection Fraction: 51% with ejection fraction >50%

Patient Populations:

  • Patients at least 54 years of age with EuroSCORE ≥5 and three-vessel coronary disease involving a marginal artery
  • Elective or subacute indication for surgery

Exclusions:

  • Previous heart surgery
  • Left ventricular ejection fraction
  • Inability to provide informed consent
  • Unstable preoperative condition

Primary Endpoints:

  • Composite of all-cause mortality, acute myocardial infarction, resuscitated cardiac arrest, low cardiac output/cardiogenic shock, stroke, or coronary re-intervention at 30 days

Secondary Endpoints:

  • Hyperdynamic shock
  • New-onset atrial fibrillation
  • Need for pacing more than 24 hours
  • Renal failure
  • Re-operation
  • Respiratory failure requiring re-intubation
  • Pneumonia
  • Length of stay in the intensive care unit and the hospital

Drug/Procedures Used:

High-risk patients (EuroSCORE ≥5) with three-vessel coronary disease were randomized to off-pump CABG (n = 177) versus on-pump CABG (n = 164).

Concomitant Medications:

Patients in the off-pump group were given 100 U/kg of unfractionated heparin to achieve an activated clotting time >200 seconds. Patients in the on-pump group were given 300 U/kg to achieve an activated clotting time >480 seconds, which was reversed with protamine sulfate at the end of the procedure.

Principal Findings:

Overall, 341 patients were randomized. There was no difference in baseline characteristics between the groups. In the off-pump arm, the mean age was 76 years, 35% were women, body mass index was 26.3 kg/m2, 18% had diabetes, 11% had chronic obstructive pulmonary disease, 21% were current smokers, 51% had an ejection fraction >50%, and the mean EuroSCORE was 6.9. The predicted 30-day mortality was approximately 3%.

In the off-pump group, 4.5% of patients crossed over to on-pump CABG (mainly due to hemodynamic instability). In the on-pump group, 3.7% of patients crossed over to off-pump CABG (mainly due to severe aortic calcification). The mean number of grafts per patient was 3.22 in the off-pump group versus 3.34 in the on-pump group (p = 0.11), whereas the mean number of grafts to the lateral wall of the heart was 0.97 versus 1.14 (p = 0.01), respectively.

The 30-day composite primary outcome occurred in 15% of the off-pump group versus 18% of the on-pump group (p = 0.47). Death was 3.4% versus 6.7%, myocardial infarction was 5.1% versus 9.2%, stroke was 4.0% versus 3.7%, coronary re-intervention was 0.6% versus 1.8%, new-onset atrial fibrillation was 43% versus 44%, re-operation for bleeding was 5.1% versus 2.4%, and hemodialysis was 4.0% versus 4.9%, respectively for off-pump versus on-pump (p = NS, for all comparisons).

Interpretation:

Among patients with three-vessel coronary artery disease and elevated clinical risk, the use of off-pump CABG is feasible. This method of revascularization is associated with similar short-term adverse events compared with on-pump CABG. While the mean number of grafts was similar between the groups, fewer grafts were placed to the lateral wall of the heart with off-pump CABG. This might affect long-term outcomes, which were shown to be worse with off-pump CABG in the larger ROOBY trial. The current trial was conducted at a single center and only reported outcomes to 30 days.

References:

Moller CH, Perko MJ, Lund JT, et al. No major differences in 30-day outcomes in high-risk patients randomized to off-pump versus on-pump coronary bypass surgery. The Best Bypass Surgery Trial. Circulation 2010;121:498-504.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention

Keywords: Renal Dialysis, Pulmonary Disease, Chronic Obstructive, Myocardial Infarction, Stroke, Body Mass Index, Cardiopulmonary Bypass, Coronary Artery Bypass, Hemodynamics, Diabetes Mellitus


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