OPCAB vs CABG: Where is the Difference? Roman M. Sniecinski, MD, FASE
Annual 2014 Associate Professor of Anesthesiology
Emory University School of Medicine
Learning Objectives 
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Explain the anesthetic implications of both techniques Describe results of major trials and potential biases Background Although not widely known, the first successful coronary artery bypass was performed in 1960 by Robert H. Goetz at the Albert Einstein College of Medicine in New York.(1) By report, the anastomosis, using a specially designed metal ring for the internal mammary artery, took under 20 seconds. The patient, who underwent the operation for intractable angina, returned to work as a taxi driver following an uneventful recovery and survived for more than a year afterwards. Several years later, Vasilii Kolesov of Russia reported an anastomosis using a suture technique more closely resembling that used in modern cardiac surgery,(2) and for a period of time it was the only technique utilized.(3) So, the birth of coronary artery bypass grafting (CABG), one of the most commonly performed elective surgical procedures in the world, actually occurred without the use of extracorporeal circulation. It is somewhat ironic that the “gold standard” became the use of cardiopulmonary bypass (CPB) for the procedure and off‐
pump coronary artery bypass (OPCAB) surgery the “newcomer.” CABG surgery using CPB The first successful use of CPB occurred in 1953 when John Gibbon closed an atrial septal defect in an 18 year old patient.(4) The technology was crude at the time, however, and it was not until much later that CPB would be applied toward coronary revascularization procedures, which were also in their infancy. The first successful coronary artery bypass using a piece of saphenous vein and extracorporeal circulation is largely credited to Rene Favaloro at the Cleveland Clinic in 1967.(5) Enthusiasm for the procedure grew and by 1969 there were around 500 hospitals in the United States with CPB capability performing around 5,000 revascularization procedures of one type or another annually.(6) Given that there are more than 13 million Americans with CAD, it is no surprise that this number has ballooned to 400,000 CABG procedures now performed annually,(7) with about 80% of them utilizing CPB. From an anesthetic point of view, the challenges of CPB come not during the actual CABG procedure, but from preparing for its initiation and separation. Factors contributing to inflammatory and hemostatic activation during CPB have been extensively reviewed and the anesthesiologist’s goal is to minimize their sequelae.(8,9) Often what is done for CABG on CPB is directly opposite to management for OPCAB. For example, fluid restriction in the pre‐CPB period is often employed to minimize hemodilution. For OPCABs, however, fluid loading is often required to ensure adequate pre‐load during cardiac manipulations. The major management differences are summarized in the table below. Major Management Differences of CABG on CPB vs OPCAB Stage of Procedure CABG on CPB Concerns OPCAB Concerns Minimize myocardial MVO2
Consider need for loading inotropes in Conduit Harvest Restrict IVF to minimize hemodilution Initiation of CPB Ensure adequate anticoagulation
Antifibrinolytic use common Distal Anastomoses Keep heart quiescent
Minimal hemodynamic disturbances Separation from CPB Ramp up inotropic support
Procedure End / Misc. Rewarming managed by perfusionist
anticipation of heart manipulations IVF administration to ensure adequate pre‐load (N/A) ACT target less well‐defined Aspirin often administered Keep heart beating; epicardial pacing often employed Major hemodynamic disturbances (N/A) Often able to wean pressors following distal completion Hypothermia a problem – need active heating measures throughout operation OPCAB Surgery From a surgical standpoint, it is more difficult to sew on a beating heart. This problem has been ameliorated by specialized devices developed and marketed in the mid‐1990’s that help position the heart and stabilize the involved section of myocardium. Despite these advances, communication between the surgeon and anesthesiologist is critical to determine what position the patient will or will not tolerate. In order to alleviate some of the hemodynamic consequences of OPCAB during distal anastomoses, surgical maneuvers such as opening the pleural space to alleviate compression and employing intracoronary shunts can be used. A 3 minute “trial” period prior to arteriotomy is helpful to avoid emergent conversion to CPB, which is associated with a significantly higher mortality rate.(10) Outcomes of CABG with CPB versus OPCAB There are passionate proponents and opponents when it comes to this issue. The major points of contention are generally summed up as follows: Pro‐OPCAB Arguments 
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Reduced neurocognitive dysfunction by avoiding cannulation and aortic cross‐clamping Avoidance of the systemic inflammatory response and its post‐op sequelae Decreased blood product use with better post‐op pulmonary and renal function Pro CABG with CPB Arguments 
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Incomplete revascularization with OPCAB / poorer long‐term graft patency Emergency conversion of OPCAB to CPB results in higher mortality OPCAB has higher degree of technical difficulty with no proven advantages Multiple randomized controlled trials have been performed to address these arguments, but most have been insufficiently powered to detect differences in a procedure with such a low morbidity and mortality rate. Some better‐known RCTs directly comparing CABG with (on) and without (off) the use of CPB are presented below with their latest follow‐up and limitations. Trial (n=On/n=Off) BHACAS I & II (201/200) Octopus Study (139/142) SMART (99/98) ROOBY Study (1099/1104) CORONARY Study (2377/2375) Follow‐up / Major Conclusions 6‐8 year FU: No difference in graft patency or perceived QOL(11) 5 year FU: No difference in cognitive function or cardiac outcome(12) 6‐8 year FU: No difference in mortality or graft patency, lower costs in OPCAB(13) 1 year FU: Lower graft patency and higher mortality in OPCAB(14) 1 year FU: No significant difference in mortality, QOL, or cognitive function(15) Notes Significant improvement in OPCAB between trials I and II Low‐risk patient population only Single center; highly experienced surgeons in OPCAB Low risk males only; very high OPCAB to CPB conversion rate Largest multicenter RCT to date; planned 5 year FU A recent Cochrane meta‐analysis of 86 trials including over ten thousand patients concluded that OPCAB provided no benefit with regard to stroke or MI and, in fact, demonstrated lower long‐term survival.(16) However, as mentioned above, most RCTs involve only low risk patients with an expected STS mortality of 1‐2%. In an observational analysis of the STS database (14,766 patients), Puskas and colleagues reported lower hospital mortality in the highest‐risk group with OPCAB.(17) It is likely that the best approach to CABG will depend upon patient risk factors and surgeon experience. Exactly what factors favor OPCAB and what surgeons are experienced enough will likely remain a matter of debate for some time. References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Goetz RH, Rohman M, Haller JD, Dee R, Rosenak SS. Internal mammary‐coronary artery anastomosis. A nonsuture method employing tantalum rings. The Journal of thoracic and cardiovascular surgery 1961;41:378‐86. Kolesov VI, Potashov LV. [Surgery of coronary arteries]. Eksperimental'naia khirurgiia i anesteziologiia 1965;10:3‐8. Konstantinov IE. Vasilii I Kolesov: a surgeon to remember. Texas Heart Institute journal / from the Texas Heart Institute of St Luke's Episcopal Hospital, Texas Children's Hospital 2004;31:349‐
58. Gibbon JH, Jr. Application of a mechanical heart and lung apparatus to cardiac surgery. Minnesota medicine 1954;37:171‐85; passim. Favaloro RG. Landmarks in the development of coronary artery bypass surgery. Circulation 1998;98:466‐78. Glenn WW. Some reflections on the coronary bypass operation. Circulation 1972;45:869‐77. Epstein AJ, Polsky D, Yang F, Yang L, Groeneveld PW. Coronary revascularization trends in the United States, 2001‐2008. JAMA : the journal of the American Medical Association 2011;305:1769‐76. Levy JH, Tanaka KA. Inflammatory response to cardiopulmonary bypass. The Annals of thoracic surgery 2003;75:S715‐20. Sniecinski RM, Chandler WL. Activation of the hemostatic system during cardiopulmonary bypass. Anesthesia and analgesia 2011;113:1319‐33. Chowdhury R, White D, Kilgo P, Puskas JD, Thourani VH, Chen EP, Lattouf OM, Cooper WA, Myung RJ, Guyton RA, Halkos ME. Risk factors for conversion to cardiopulmonary bypass during off‐pump coronary artery bypass surgery. The Annals of thoracic surgery 2012;93:1936‐41; discussion 42. Angelini GD, Culliford L, Smith DK, Hamilton MC, Murphy GJ, Ascione R, Baumbach A, Reeves BC. Effects of on‐ and off‐pump coronary artery surgery on graft patency, survival, and health‐
related quality of life: long‐term follow‐up of 2 randomized controlled trials. The Journal of thoracic and cardiovascular surgery 2009;137:295‐303. 12. 13. 14. 15. 16. 17. van Dijk D, Spoor M, Hijman R, Nathoe HM, Borst C, Jansen EW, Grobbee DE, de Jaegere PP, Kalkman CJ. Cognitive and cardiac outcomes 5 years after off‐pump vs on‐pump coronary artery bypass graft surgery. JAMA : the journal of the American Medical Association 2007;297:701‐8. Puskas JD, Williams WH, O'Donnell R, Patterson RE, Sigman SR, Smith AS, Baio KT, Kilgo PD, Guyton RA. Off‐pump and on‐pump coronary artery bypass grafting are associated with similar graft patency, myocardial ischemia, and freedom from reintervention: long‐term follow‐up of a randomized trial. The Annals of thoracic surgery 2011;91:1836‐42; discussion 42‐3. Shroyer AL, Grover FL, Hattler B, Collins JF, McDonald GO, Kozora E, Lucke JC, Baltz JH, Novitzky D. On‐pump versus off‐pump coronary‐artery bypass surgery. The New England journal of medicine 2009;361:1827‐37. Lamy A, Devereaux PJ, Prabhakaran D, Taggart DP, Hu S, Paolasso E, Straka Z, Piegas LS, Akar AR, Jain AR, Noiseux N, Padmanabhan C, Bahamondes JC, Novick RJ, Vaijyanath P, Reddy SK, Tao L, Olavegogeascoechea PA, Airan B, Sulling TA, Whitlock RP, Ou Y, Pogue J, Chrolavicius S, Yusuf S. Effects of off‐pump and on‐pump coronary‐artery bypass grafting at 1 year. The New England journal of medicine 2013;368:1179‐88. Moller CH, Penninga L, Wetterslev J, Steinbruchel DA, Gluud C. Off‐pump versus on‐pump coronary artery bypass grafting for ischaemic heart disease. The Cochrane database of systematic reviews 2012;3:CD007224. Puskas JD, Thourani VH, Kilgo P, Cooper W, Vassiliades T, Vega JD, Morris C, Chen E, Schmotzer BJ, Guyton RA, Lattouf OM. Off‐pump coronary artery bypass disproportionately benefits high‐
risk patients. The Annals of thoracic surgery 2009;88:1142‐7.