Heart, Lung and Circulation 2003; 12: 123–124

Editorial

Off-pump coronary artery bypass: Where are we?

Michael Gardner, MB BS, FRACS

St Andrews Heart Institute and The Prince Charles Hospital, Brisbane, Australia

ff pump coronary bypass grafting (OPCAB) isnow practised in most Australian cardiacsurgical units for selected patients undergoing

surgical coronary revascularisation. However, thenumber of OPCAB cases undertaken by individualcardiac surgeons is widely variable, ranging from few ornone to those who perform the majority of their coronaryoperations off pump. There are a number of reasons forthis divergent approach, not the least of which are thegenerally held concerns that OPCAB leads to less accu-rate, poor quality coronary anastomotic construction anda tendency or temptation to perform fewer than therequired number of grafts for complete revascularisation.Coupled with this has been the difficulty of clearlydemonstrating a major improvement in morbidity andmortality for the average low risk patient when com-pared to conventional coronary bypass surgery (coronaryartery bypass grafting, CABG). The early hope that theelimination of cardiopulmonary bypass would produce amajor reduction in complications has not been realised.Nevertheless, comparative studies to date for low riskpatients have shown advantages for OPCAB, namelylower transfusion rate, lower cardiac enzyme release,shorter hospital stay and cost savings.1–3 Other non-randomised comparative studies with large patientpopulations evaluated by sophisticated statisticalmethods suggest that operative mortality and morbiditymight be lower with OPCAB.4,5 Most of these publishedreports, however, relate to perioperative and early post-operative results.

In view of the relative lack of detailed clinical follow-up studies for OPCAB, the paper ‘Five year clinicalfollow-up of patients who have had off pump coronarybypass grafting’, written by Newman, Alvarez andKolybaba and published in this issue of Heart, Lung andCirculation, makes an important contribution.6 Newmanet al. report on the follow up of all 312 patients who

underwent OPCAB between 1997 and December 2000 atSir Charles Gairdner Hospital, Perth, showing that theactuarial survival at 5 years was 94.6% and freedom fromcardiac related events was 92.1%. This certainly com-pares very favourably with the results of conventionalCABG. If the concerns of poorly executed distal anasto-moses and incomplete revascularisation were realised,then ischaemic symptoms would be expected to returnduring this follow-up time frame. It is also important torecognise that this series represents a total experienceand includes all patients undergoing OPCAB since theprogram started in 1997, which means that the studyincludes the early learning curve.

Based on this experience Newman et al. have raisedseveral concerns regarding OPCAB. The avoidance ofcardiopulmonary bypass means that the coagulationmechanism is not disturbed to the same extent and, infact, these patients might become procoagulant in theearly postoperative phase. This raises the issue of suscep-tibility to potential early graft thrombosis, deep venousthrombosis and thrombosis of recently stented coronaryarteries (as demonstrated by Newman et al.). These prob-lems have been duplicated early in our own experienceat St Andrews and The Prince Charles Hospitals, Bris-bane necessitating alteration and attention to the anti-coagulation regime for patients undergoing OPCAB.Although the optimal regime is not known, it is now thepolicy at St Andrews and The Prince Charles Hospitals tocontinue aspirin up until surgery, giving 5000 units ofsubcutaneous heparin preoperatively the night before.Heparin is given to achieve an activated clotting time(ACT) of >350 during the performance of the operationand half reversed at the end unless bleeding is excessive.Aspirin and calcium heparin are commenced later thesame day of operation or at latest early the followingmorning. The addition of clopidogrel would seem appro-priate if there has been recent intracoronary stenting.

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124 M. Gardner Heart, Lung and Circulation 2003; 12Editorial

It is pertinent to ask if this procoagulant effect is alsorelevant with respect to the risk of stroke (e.g. areOPCAB patients more likely to form intracardiac throm-bus with postoperative atrial fibrillation?) Of interest is areport from Quigley et al., which reported on 290 offpump patients with arterial conduits and no aorticanastomoses. Surprisingly, five of these patients suffereda postoperative cerebrovascular accident.7

Newman et al. also raised the possibility of anincreased risk of aortic dissection associated with side-biting clamps placed on a pulsatile ascending aorta, withNewman experiencing two such complications. Thisissue was raised previously by Chavanon et al.8 In 1999 areview was conducted of postoperative acute aortic dis-section at Prince Charles and St Andrews Hospitals9 andisolated 16 patients who presented with the complica-tion, from a total of 12 361 open-heart procedures(0.13%). In 10 of the 16 patients the aorta was consideredmacroscopically abnormal at operation and in fivepatients the dissection appeared to have arisen in thesaphenous vein graft anastomotic site on the aorta. In ourseries of OPCAB patients, now exceeding 700, we havenot seen this complication. This risk might be morerelated to an abnormal aorta or any entry point in theaorta, including a proximal anastomosis, rather than theside-biting clamp itself. However, this together with con-cerns regarding embolisation from the abnormal aortaclamped with a side biting clamp suggests that optimallyduring OPCAB the aorta should be avoided completelywhere possible.

For multiple graft operations off pump utilisation ofboth internal mammary arteries (IMA) provides ade-quate inflow. A skeletonised harvest of the IMA isadvantageous as the conduits are longer, larger, do nottend to kink or twist and are more versatile in theirutilisation. They are well suited to the construction ofsequential anastomoses, T or Y grafts, and can be length-ened or extended by composite grafting with segmentsof radial artery or opposite IMA. This allows multiplegrafts to all areas of the heart with dual inflow andavoidance of aortic manipulation. A skeletonised harvest

of the IMA leaving the mammary veins undisturbed isalso relatively atraumatic to the chest wall, expanding itsuse to some patients with obesity and diabetes.

Newman's excellent work should give confidence toAustralian cardiac surgeons to pursue their OPCAB pro-grams. With the techniques well established, the focus isnow moving to the higher risk categories of patients totry and determine whether OPCAB is of significantbenefit in this group. Certainly those patients withatheromatous or calcific disease in the ascending aortaand those at a high risk of stroke with conventionalsurgery should benefit substantially from the OPCABtechnique. The off pump technique should be part of thearmamentarium of all coronary artery surgeons.

References1. van Dijk D, Nierich AP, Jansen EWL et al. Early outcome after

off-pump versus on-pump coronary bypass surgery. Resultsfrom a randomized study. Circulation 2001; 104: 1761–6.

2. Nathoe HM, van Dijk D, Jansen EW et al. Octopus study group.N. Engl. J. Med. 2003; 348: 394–402.

3. Puskas J, Thourani V, Marshall J et al. Clinical outcomes, angio-graphic patency, and resource utilization in 200 consecutive off-pump coronary bypass patients. Ann. Thorac. Surg. 2001; 71:1477–84.

4. Mack M, Bachand D, Acuff T et al. Improved outcomes incoronary artery bypass grafting with beating-heart techniques.J. Thorac. Cardiovasc. Surg. 2002; 124: 598–607.

5. Magee MJ, Jablonski KA, Stamou SC et al. Elimination of cardio-pulmonary bypass improves early survival for multivesselcoronary artery bypass patients. Ann. Thorac. Surg. 2002; 73:1196–203.

6. Newman MA, Alvarez JM, Kolybaba ML. Five year clinicalfollow-up of patients who have had off pump coronary bypassgrafting. Heart, Lung Circ. 2003; 12: 157–161.

7. Quigley RL, Weiss SJ, Highbloom RY, Pym J. Creative arterialbypass grafting can be performed on the beating heart. Ann.Thorac. Surg. 2001; 72: 793–7.

8. Chavanon O, Carrier M, Cartier R et al. Increased incidence ofacute ascending aortic dissection with off-pump aortocoronarybypass surgery? Ann. Thorac. Surg. 2001; 71: 117–21.

9. Ambazidis E, Gardner M, Tesar P. Aortic dissection followingopen heart surgery. Heart, Lung Circ. 2000; 9: A27.