A study design to assess the safety and efficacy of on-pump versus off-pump coronary bypass grafting: the ROOBY trial

Abstract

Since the late 1960s, coronary artery bypass graft (CABG-only) procedures were traditionally performed using a heart-lung machine on an arrested heart (on-pump). Over the past decade, an increasing number CABG-only procedures were performed on a beating heart (off-pump). Advocates of the off-pump approach expect to reduce many of the adverse side effects related to using the heart-lung machine, while advocates for the on-pump procedure raise concerns related to graft patency rates and long-term event-free survival for the off-pump technique. The U.S. Department of Veteran Affairs (VA) Cooperative Studies Program funded a randomized, multicenter clinical trial comparing the clinical and resource-related outcomes following on-pump versus off-pump techniques for veterans undergoing a non-emergent CABG-only procedure. The planning committee was faced with several critically important challenges to assure feasibility of study costs and required sample size; generalizability to non-VA surgical practices; and comparability of clinically meaningful results. These challenges are discussed. This study is a prospective, randomized, multicenter, single blinded (patient) clinical trial that compares on-pump and off-pump techniques for veterans requiring non-emergent CABG-only procedures. There will be 2200 patients randomized at 17 VA Medical Centers when the five-year recruitment period ends on 15 April 2007. There are two primary objectives: a short-term objective to assess the immediate impact of the two techniques on 30-day mortality/morbidity and a long-term objective to assess one-year mortality/morbidity. Major secondary outcomes are one-year graft patency rates and change in neuropsychological assessments from baseline to one year. All patients are assessed at 30 days post-surgery or discharge from the hospital, whichever is latest, and at one-year post-surgery. During planning, several key issues had to be decided. These included 1) choosing primary objectives: a short-term (30-day) and a long-term (one-year) objective were chosen; 2) choosing primary outcome measures: composite measures were selected to ensure sufficient end-points; 3) standardization of surgical techniques: minimal standardization required but guidelines and continuing discussions on both techniques provided; 4) establishing criteria for surgeons and residents for participation: surgeons required to have completed 20 off-pump procedures prior to doing study procedures and residents, in presence of study surgeon, capable of doing either procedure; 5) identifying metrics of cognitive dysfunction sensitive to treatment: a neuropshychologist hired who centrally monitors cognitive functioning testing; and 6) blinding participants of surgical procedure: attempt to blind participants. Areas of concern are whether all surgeons sufficiently experienced on the off-pump procedure, should residents have been allowed to do study surgeries, should techniques have been standardized more and were the best neurocognitive tests selected. The study design presented allows for a balanced and fair assessment of the on-pump and off-pump CABG procedures across a diversity of clinical outcomes and resource use metrics. Its results have the potential to influence clinical cardiac surgical practice in the future.