Practice Update: Cardiology

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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.
COMMENT
By Hartzell V Schaff MD
The 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
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.
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.
CARDIAC PROCEDURES & SURGERIES 26
PRACTICEUPDATE CARDIOLOGY