Off Pump vs On Pump CABG

OVERVIEW

Off pump CABG is:

• widely performed
• safe
• effective
• and there are numerous techniques available – limited thoracotomy, video assisted

On or off pump CABG is primarily a balance of:

• an easy, bloodless surgical field, with
• the risks of bypass and embolic events from clamping and cannulating the aorta

Off pump CABG is generally preferred in:

• patients with aortic disease precluding bypass
• patients at higher risk of complications from CPB such as: ventricular dysfunction, renal insufficiency, diabetes, advanced age, and chronic lung disease

ADVANTAGES

avoids bypass

• no aortic cannulation -> less risk of dissection, embolism
• no atrial cannulation -> less atrial injury, arrhythmias
• no cross-clamping -> less risk of plaque embolism, CVA, MI
• no activation of coagulation, kallikrein, inflammation caused by tubing -> less coagulopathy, less bleeding, less transfusion
• no cardioplegia -> no K+ load, fluid load, coronary air embolism
• no risk of bypass machine failure -> air embolism
• less cost
• less equipment
• less staff

The CORONARY study (NEJM RCT 2012) suggests off-pump performed by experts is as good as on-pump

DISADVANTAGES

• needs skilled staff
• technically more difficult (increased risk of anastomotic bleeding, suboptimal revascularisation, myocardial ischaemia)
• not all coronary arteries well reached by technique
• potential for MI without cardioplegia
• more graft failure
• incomplete revascularisation more frequent
• worse long-term graft outcomes in some studies (e.g. ROOBY, 2009)
• proposed neuropsychological benefit not shown in trial
• more difficult in diffuse disease or small artery disease

EVIDENCE

• larger observational studies generally favour off pump CABG than the smaller RCTs that have been performed

ROOBY trial (NEJM, 2009) [PMID: 19890125.]

• MCRCT
• US
• 2002-2008
• n = 2200
• randomised to on pump vs off pump
• primary short term outcomes: death, major complications (reoperation, new mechanical support, cardiac arrest, coma, stroke, renal failure requiring dialysis) within 30 days
• primary long-term outcomes: 1 year mortality, non-fatal MI @ 1 year, repeat revascularisation @ 1 year
• secondary endpoints: completeness of revascularisation, graft patency @ 1 year, neuropsychological test

-> no difference in primary short term outcomes -> no difference in survival -> trend towards greater complications in off pump (primary long term) -> off pump group received less grafts then were originally planned -> off pump group grafts were less patent -> no difference in neuropsychological outcomes -> less transfusions in off pump group -> off pump: longer OT times, LOS same, time of ventilation same

SUMMARY: better to do CABG on pump

Khan NE, et al. A randomised comparison of off-pump and on-pump multivessel coronary-artery bypass surgery. N Engl J Med 2004; 350:21-28. [PMID 14702424]

• RCT
• on pump vs off pump
• followed up at 3 months
• mean of 3 grafts -> on pump grafts had a significant increase in patency

GOPCABE NEJM 2012 [PMID: 23477657]

• RCT found no difference between on-pump and off-pump CABG for elderly patients >75 years undergoing CABG (at 30 days and 12 months)

CORONARY study, NEJM April 19, 2012 [PMID: 22449296.]

• RCT of 4752 patients
• primary outcome = composite of 30 day death, stroke, MI or new renal failure
• No difference between off-pump vs on-pump CABG
• Off-pump had significant lower rates of blood-product transfusion, return to theatre for bleeding, acute kidney injury and respiratory complications, but more early repeat revascularisations ( 0.7 vs 0.2%)
• Only surgeons familiar with off-pump involved (and no trainees as primary surgeons), and ?a higher risk group of patients
• suggests off-pump CABG performed by experts gives good results

References and Links

• Khan NE, et al. A randomized comparison of off-pump and on-pump multivessel coronary-artery bypass surgery. N Engl J Med. 2004 Jan 1;350(1):21-8. [PMID 14702424]
• GOPCABE Study Group. Off-pump versus on-pump coronary-artery bypass grafting in elderly patients. N Engl J Med. 2013 Mar 28;368(13):1189-98. PMID: 23477657.
• Hemmerling TM, Romano G, Terrasini N, Noiseux N. Anesthesia for off-pump coronary artery bypass surgery. Ann Card Anaesth. 2013 Jan-Mar;16(1):28-39. PMID: 23287083.
• CORONARY study. Off-pump or on-pump coronary-artery bypass grafting at 30 days. N Engl J Med. 2012 Apr 19;366(16):1489-97. PMID: 22449296.
• Pepper J. Recent data on off-pump coronary artery bypass grafting: the CORONARY and GOPCABE trials. EuroIntervention. 2013 May 20;9(1):29-32. PMID: 23685292.
• Polomsky M, Puskas JD. Off-pump coronary artery bypass grafting–the current state. Circ J. 2012;76(4):784-90. PMID: 22451446.
• Randomized On/Off Bypass (ROOBY) Study Group. On-pump versus off-pump coronary-artery bypass surgery. N Engl J Med. 2009 Nov 5;361(19):1827-37. PMID: 19890125.