Overview: Coronary-artery bypass grafting (CABG) is open heart surgery to treat coronary artery disease using a blood vessel (a graft) taken from the chest wall, leg or arm to bypass a narrowed or blocked coronary artery. A CABG does not cure coronary artery disease so it is possible for blockages to recur in both the grafts and other blood vessels. However, it does improve symptoms such as angina.
Current treatment: Traditional CABG operations are performed 'on-pump' whereby the heart and lungs are connected to a bypass machine that takes over to add oxygen to the blood and maintain circulation. 'Off-pump' CABG is an alternative technique that doesn't require the patient to be connected to a heart-lung (bypass) machine.NICE states that current evidence on the safety and efficacy of off-pump coronary artery bypass appears adequate to support the use of this procedure, only when performed through a median sternotomy.
New evidence: The ROOBY study by Shroyer et al (N Engl J Med. 2009 Nov 5;361(19):1827-37) compared outcomes for 2203 patients randomised to receive on-pump or off-pump CABG for urgent or elective procedures. A standard median sternomy was performed on all patients in the study. There was no difference between the two groups for the short-term (30-day) composite outcome of death or complications. However, the off-pump CABG group experienced poorer outcomes for the other composite primary endpoint at 1 year — the rate of death, repeat revascularisation procedure or nonfatal myocardial infarction was significantly higher in this population. Graft patency and the completed number of planned interventions were also lower in the off-pump CABG group.The findings support current treatment but further research is required.
Commentary: ""This important paper enhances knowledge of off pump CABG surgery. Large surgical randomized trials are unusual because of logistical difficulties and expense. "However, I don't believe that off pump CABG can be discounted based on these findings. Substantial evidence, albeit retrospective, suggests that high risk patients suffer fewer deaths and complications after off pump surgery but patients with co-morbidities were largely excluded from this trial."The significant difference between the number of grafts planned and the number of grafts completed in the off pump group suggests inexperience of surgeons. Surgeons were eligible if they had completed 20 prior off pump procedures. Because different coronary territories are not equally amenable to grafting, experience in one territory does not necessarily provide the experience and ability to treat triple vessel coronary disease. "Surgeon inexperience may also partially explain the inferior patency figures in grafts completed off pump. Postoperative coagulopathy may also have contributed to the increase in occluded grafts. New antiplatelet drugs such as clopidogrel, which are not routinely used in CABG surgery, may reverse the effect. "The CRISP trial, which has just opened recruitment, will compare outcomes after on pump and off pump CABG in high risk patients (ISRCTN29161170, MRC ref: G0700469).
Commentary: ""This important paper enhances knowledge of off pump CABG surgery. Large surgical randomized trials are unusual because of logistical difficulties and expense. "However, I don't believe that off pump CABG can be discounted based on these findings. Substantial evidence, albeit retrospective, suggests that high risk patients suffer fewer deaths and complications after off pump surgery but patients with co-morbidities were largely excluded from this trial."The significant difference between the number of grafts planned and the number of grafts completed in the off pump group suggests inexperience of surgeons. Surgeons were eligible if they had completed 20 prior off pump procedures. Because different coronary territories are not equally amenable to grafting, experience in one territory does not necessarily provide the experience and ability to treat triple vessel coronary disease. "Surgeon inexperience may also partially explain the inferior patency figures in grafts completed off pump. Postoperative coagulopathy may also have contributed to the increase in occluded grafts. New antiplatelet drugs such as clopidogrel, which are not routinely used in CABG surgery, may reverse the effect. "The CRISP trial, which has just opened recruitment, will compare outcomes after on pump and off pump CABG in high risk patients (ISRCTN29161170, MRC ref: G0700469).
Trial organisers have taken steps to ensure that off pump operations are carried out by very experienced off pump surgeons." - Joint analysis was provided by Professor Tom Quinn clinical lead for NHS Evidence - cardiovascular, stroke and vascular collections and Professor of Clinical Practice at the Faculty of Health and Medical Sciences, University of Surrey; Mr Norman Briffa, cardiothoracic surgeon from Sheffield and Professor Mike Larvin, Clinical Lead for NHS Evidence - Surgery and Professor of Surgery at the University of Nottingham.
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