Practice Update: Cardiology

ImprovedOutcomes WithOn- vs Off- Pump Coronary- Artery Bypass The New England Journal of Medicine Take-home message • This multisite study evaluated long-term outcomes among 2203 patients undergoing coronary artery bypass grafting (CABG) with (on pump) or without (off pump) cardiopulmonary bypass. The rate of death and major cardiovascular events at 5 years in the off-pump group (15.2% and 31.0%, respectively) was significantly higher compared with the rates in the on-pump group (11.9%and 27.1%, respectively). The rate of repeat CABG was significantly higher in the off-pump group (1.4% vs 0.5%). There were no significant differences between groups in terms of nonfatal myocardial infarction, cardiac death, or repeat revascularization at 5 years. • For patients undergoing CABG, 5-year survival and event-free survival were significantly longer in patients who underwent cardiopulmonary bypass compared with those who did not. Abstract BACKGROUND Coronary-artery bypass grafting (CABG) surgery may be performed either with cardiopulmonary bypass (on pump) or without cardiopulmonary bypass (off pump). We report the 5-year clinical outcomes in patients who had been included in the Vet- erans Affairs trial of on-pump versus off-pump CABG. METHODS From February 2002 through June 2007, we randomly assigned 2203 patients at 18 medical centers to undergo either on-pump or off-pump CABG, with 1-year assessments completed by May 2008. The two primary 5-year outcomes were death from any cause and a composite outcome of major adverse cardiovascular events, defined as death from any cause, repeat revascularization (CABG or percutaneous coronary intervention), or nonfatal myocar- dial infarction. Secondary 5-year outcomes included death from cardiac causes, repeat revascularization, and nonfatal myocardial infarction. Primary outcomes were assessed at a P value of 0.05 or less, and secondary outcomes at a P value of 0.01 or less. RESULTS The rate of death at 5 years was 15.2% in the off-pump group versus 11.9% in the on-pump group (relative risk, 1.28; 95% confidence interval [CI], 1.03 to 1.58; P=0.02). The rate of major adverse cardiovascular events at 5 years was 31.0% in the off- pump group versus 27.1% in the on-pump group (relative risk, 1.14; 95% CI, 1.00 to 1.30; P=0.046). For the 5-year secondary outcomes, no significant differences were observed: for nonfa- tal myocardial infarction, the rate was 12.1% in the off-pump group and 9.6% in the on-pump group (P=0.05); for death from cardiac causes, the rate was 6.3% and 5.3%, respectively (P=0.29); for repeat revascularization, the rate was 13.1% and 11.9%, respec- tively (P=0.39); and for repeat CABG, the rate was 1.4% and 0.5%, respectively (P=0.02). CONCLUSIONS In this randomized trial, off-pump CABG led to lower rates of 5-year survival and event-free survival than on-pump CABG. Five-year outcomes after on-pump and off-pump coronary-artery bypass. N Engl J Med 2017 Aug 17;377(7)623-632, AL Shroyer, B Hattler, TH Wagner, et al. www.practiceupdate.com/c/57057 CARDIAC PROCEDURES & SURGERIES 26

COMMENT By Hartzell V Schaff MD T he report, “Five-Year Outcomes after On-Pump and Off-pump Coro- nary-Artery Bypass,” presents additional follow-up of patients in the Randomized On/Off Bypass (ROOBY) trial sponsored by the Depart- ment of Veteran Affairs. The bottom line is that in comparisonwith on-pump revascularization, off-pump coronary artery bypass (CABG) led to lower five year survival (84.8% vs 88.1%, P = .02) and lower event-free survival at 5 years (69% vs 72.9%, P = .46). The findings may disappoint, but should not surprise, advocates of off-pump CABG. Multiple previous nonrandomized and randomized comparative studies have demonstrated that off-pump revascularization results in slightly fewer grafts (distal anastomoses) per patient, and there is evidence from both the ROOBY study and other trials that bypass graft patency is inferior compared to on-pump CABG. 1,2 Surgeons who favor off-pump CABG argue that the technique reduces cost and postoperative complications such as stroke, homologous blood transfusion, and atrial fibrillation compared with on-pump CABG. These potential early advantages must beweighed against any detrimental effect on late survival and functional status. The ROOBY trial is not the only clinical study that documents reduced survival of patients having off-pump versus on-pump CABG. 3 A very important report by Kim et al. analyzed long-term survival of more than 5000 Korean patients who underwent isolated CABG from 1989 through 2012. 4 In this study, patients undergoing off-pump CABG had similar perioperativemortality comparedwith patients having on-pump surgery, but off-pump CABG patients has fewer distal anastomoses (3.0 vs 3.7, P < .001), and, importantly, off-pump CABG was associated with higher risk of death (HR: 1.43, P < .0001) during median follow-up of 6 years. Critics have pointed out that surgical outcomes of the ROOBY trial may not reflect what can be achieved with off-pump revascularization because operators in the Veterans Administration study were not uniformly experi- enced with the method. 5 And although technical proficiency is important for off-pump revascularization as it is for other surgical procedures, it is not clear that in the ROOBY study, surgeon experience relates directly to graft patency. 6 What is clear is that for most patients undergoing surgical coro- nary revascularization inmost centers, the advantages of cardiopulmonary bypass in providing a quiet and relatively bloodless field will improve out- come of CABG as reflected in extent of revascularization, graft patency, and long-term survival. The off-pump technique may be useful in spe- cial circumstances where there is favorable coronary anatomy (eg, right coronary artery and/or left anterior descending coronary disease) and/or References 1. Hattler B, Messenger JC, Shroyer AL, et al. Off-Pump coronary artery bypass surgery is associated with worse arterial and saphenous vein graft patency and less effective revascularization: Results from the Veterans Affairs Randomized On/Off Bypass (ROOBY) trial. Circulation 2012;125(23): 2827–2835. 2. Houlind K, Fenger-Grøn M, Holme SJ, et al. Graft patency after off-pump coronary artery bypass surgery is inferior even with identical heparinization protocols: results from the Danish On-pump Versus Off-pump Randomization Study (DOORS). J Thorac Cardiovasc Surg 2014;148(5):1812–1819. 3. Takagi H, Umemoto T. Worse long-term survival after off-pump than on-pump coronary artery bypass grafting. J Thorac Cardiovasc Surg 2014;148(5):1820-1829. 4. Kim JB, Yun S-C, Lim JW, et al. Long-Term Survival Following Coronary Artery Bypass Grafting: Off-Pump versus On-Pump Strategies. J Am Coll Cardiol 2014;63(21):2280-2288. 5. Puskas JD, Mack MJ, Smith CR. On-pump versus off-pump CABG. N Engl J Med 2010;362(9):851; author reply 853-854. 6. Almassi GH, Carr BM, Bishawi M, et al. Resident versus attending surgeon graft patency and clinical outcomes in on- versus off-pump coronary artery bypass surgery. J Thorac Cardiovasc Surg 2015;150(6):1428-1435. specific unfavorable patient characteristic such as exten- sive atherosclerotic disease in the ascending aorta, which predisposes patients to embolic stroke with aortic manip- ulation for cardiopulmonary bypass. Dr Schaff is the Stuart W. Harrington Professor of Surgery and Consultant in the Division of Cardiovascular Surgery at Mayo Clinic, Rochester, Minnesota.

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