Cirugía Cardiovascular

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e2 D.P. Taggart / Cir Cardiov. 2016;23(1):e1–e3
In contrast to the findings in these large randomized trials
several large propensity matched databases have reported early
benefits of OPCABG over ONCABG. While these databases have the
advantage of including tens of thousands of patients and propen-
sity matching for certain risk factors they can still be susceptible to
confounding factors that may be known or unknown. Kuss and col-
leagues performed a propensity score analyses of 123,137 patients
undergoing ONCABG or OPCAB nd reported that the overall
hazard ratiowas less than 1for all outcomes, favoring OPCABG. This
benefit was significant for mortality (HR, 0.69; 95% CI: 0.60–0.75),
stroke, renal failure, red blood cell transfusion (P < .0001), wound
infection (P < .001), prolonged ventilation (P < .01), inotropic sup-
port (P = .02), and intraaortic balloon pump support (P = .05) while
the hazard ratios for myocardial infarction, atrial fibrillation, and
reoperation for bleeding were not significant.
Puskas and colleague dentified 876,081 patients from the
STS database of whom 210,469 underwent CABG at sites that had
performed more than 300 OPCABG and 300 ONCABG during the
6-year study period (“high-volume sites”). Outcomes were ana-
lyzed both for all sites and for high-volume sites and stratified by
participant center and surgeon, and adjusted for 30 variables that
comprise the STS CABG riskmodel. They reported that OPCABGwas
associatedwith a significant reduction in risk of death, stroke, acute
renal failure, mortality or morbidity, and postoperative length of
stay.
Long term outcomes
In 2014 Takagi and colleagues reported worse 5-year survival
with OPCABG rom 5 randomized trials and 17 observational
studies with 104,306 patients, a pooled analysis demonstrated a
7% increase in long-term mortality with OPCABG (HR, 1.07; 95%
CI, 1.03–1.11; P = .0003). In contrast, the same year, Chaudhry and
colleague eported in a systematic review of 32 studies that
OPCABG had similar 5-year survival when compared with ONCABG
(HR, 1.06; 95% CI, 0.95–1.19; P = 0.31). They also reported that while
ONCABGhad a trend toward a 10-year survival advantage (HR, 1.06;
95% CI, 1.00–1.13; P = 0.05) this disappeared when subgroup analy-
sis of only randomized controlled trials, registry-based studies, and
propensity-matched studies was performed.
Graft patency
Zhang and colleague xamined 12 randomized controlled tri-
als, for a total of 3894 OPCABG grafts and 4137 ONCABG grafts
performed during OPCAB and ONCAB. For OPCABG, meta-analysis
showed an increased risk of occlusion of all grafts (HR: 1.35; 95%
CI: 1.16–1.57) and saphenous vein grafts (SVGs) (HR, 1.41; 95% CI,
1.24–1.60), but no significant difference in graft occlusion of left
internal mammary artery (LIMA) (HR 1.15; 95% CI, 0.83–1.59) and
radial artery (HR 1.37; 95% CI, 0.76–2.47).
Neurologic injury
Focal stroke or diffuse neurologic injury, although relatively
uncommon, remains one of the most devastating complications of
CABG. The presence of aortic atherosclerosis has been recognized as
one of the strongest predictors of overt neurological injury for over
two decades voidance or minimization of aortic manipulation
(cannulation, clamping, side biting) has been shown to reduce the
risk of cerebral injury hile gross disease and/or calcification
of the aorta may be obvious on visual inspection or by palpation,
epiaortic scanning is necessary to detect less overt disease and
particularly on the endoluminal surface. We previously reported
that any aortic manipulation including the use of side biting clamps
resulted in an increased number of solid and gaseous microemboli
even from apparently healthy aortas lthough the Cochrane
revie nd two largest randomized trial eported no signif-
icant difference in the incidence of stroke between ONCABG and
OPCAB two large propensity matched registries reported a reduc-
tion in stroke with OPCABG owever none of these studies
addressed the issue of a no touch aortic technique for OPCABG. Mis-
feld and colleagues inmeta-analyses of eight observational studies,
including 5619 OPCABG patients who underwent a no touch aortic
technique reported significantly lower neurologic complications
(HR, 0.46; 95% CI, 0.29–0.72; P = .0008) than 5779 ONCABG
patients who experienced some form of aortic manipulation
Likewise, Emmert and colleague eported that in comparison
to partial aortic clamping, OPCABG patients undergoing a non-
clamping approach had a significantly reduced frequency of stroke
(0.7% vs. 2.3%; HR = 0.39; CI 95%, 0.16–0.90; P = .04) and MACCE
(6.7% vs. 10.8%; HR = 0.55; CI 95%, 0.38–0.79; P= .001), and these
results were similar to those of the control group, who underwent
no-touch total arterialrevascularization (stroke rate, 0.8%; MACCE,
7.9%).
Summary
Current evidence from randomized trials strongly indicates that
for most patients undergoing contemporary bypass grafting there
is little to choose between ONCABG and OPCABG in terms of patient
safety. This is however predicated on the assumption that the
OPCABG surgeon is highly experienced in this technically more
challenging method because there is robust evidence, that in the
hands of inexperienced surgeons, OPCABG leads to a high rate of
cross overs and less complete revascularization. Even when per-
formed by experienced surgeons OPCABG may result in inferior
venous graft patency (possibly due to the loss of the anti-platelet
effect of CPB and so dual antiplatelet medication is recommended).
On the other hand, there is good evidence that OPCABGwhen incor-
porating a no touch aortic technique can significantly reduce the
risk of stroke. In contrast to randomized trials large propensity
matched registries have reported that OPCABG reduces postop-
erative mortality and most aspects of morbidity. Lastly, although
there is conflicting evidence whether OPCABG reduces long-term
survival this is almost certainly true if performed by inexperienced
surgeons who do not achieve complete revascularization.
So why is there still firmly a place for OPCABG in 2015? The
answer is simple: it is because there are, undoubtedly, certain
cohorts of patients who do benefit from OPCABG e.g. patients with
heavily diseased calcified or porcelain aortas who are at high risk
of stroke from any aortic manipulation. However to be able to per-
form OPCABG consistently safely and efficiently in such situations
it is essential that the surgeon is confident and proficient with the
technique. The dilemma, however, is that to achieve this level of
competency it requires that the surgeon performs the operation
regularly as no occasional operation is a good operation. Themantra
from some surgeons that ‘I reserve OPCABG’ for my difficult cases is
illogical as the worst time to change technique is when faced with
a difficult operation. This also raises the question of whether this
technique for CABG should be considered a sub-specialty allow-
ing some surgeons to gain the appropriate expertise and to teach
trainees. A final concluding thought is that, in terms of overall ben-
efits to most patients undergoing CABG, it is far more important to
use two internal mammary arteries, because of their superior sur-
vival advantage han whether the operation is performed on or
off pump.
Conflict of interests
The author declares no conflict of interest.