TITLE: Increased patency with comparable mortality and revascularization
risk: Is the case for no-touch vein harvesting open and shut?
RUNNING TITLE: Vein harvesting technique for CABG
Makoto Hibino, MD MPH PhD, Nitish K Dhingra, BHSc, Subodh Verma, MD PhD
Division of Cardiac Surgery, the Li Ka Shing Knowledge Institute of St.
Michael’s Hospital, University of Toronto, Toronto
Funding: none
Correspondence: Makoto Hibino, MD MPH PhD,
Division of Cardiac Surgery, the Li Ka Shing Knowledge Institute of St.
Michael’s Hospital, University of Toronto, 30 Bond St, Toronto, ON,
Canada M5B 1W8.
Email mhibino-ngy@umin.org
ABSTRACT
Since the introduction of the saphenous vein graft (SVG) for coronary
artery bypass grafting (CABG) in 1962, the SVG has
remained the most commonly used conduit to the non-LAD territories for
more than half a century. However, several issues surrounding the use of
SVGs, including higher graft occlusion rates and wound complications
from the harvesting process, have been identified in clinical practice.
As such, significant interest has been dedicated towards developing
harvesting techniques that minimize the risk of these acute and late
complications. In this issue of the Journal of Cardiac Surgery, Yokoyama
and colleagues compared the impact of open vein harvesting (OVH),
endoscopic vein harvesting (EVH) and no-touch vein harvesting (NT) on
all-cause mortality, revascularization and graft failure, using a
network meta-analysis based on randomized controlled trials and
propensity-score matched studies. The results showed that the risk of
graft failure was approximately halved amongst patients receiving NT
compared with EVH and OVH; importantly, though, NT was not associated
with lower all-cause mortality or revascularization risk. To further
examine whether the use of NT grafts endow patients with better
long-term clinical outcomes, such as mortality, myocardial infarction,
and revascularization rates, a large-scaled randomized controlled trial
or a patient-level combined meta-analysis is required.
MANUSCRIPT
Since the introduction of the saphenous vein graft (SVG) for coronary
artery bypass grafting (CABG) in 19621, the SVG has
remained the most commonly used conduit to the non-LAD territories for
more than half a century.2 Despite its widespread use,
the SVG failure rate remains as high as 40-50% at 10 years, which can
result in the reoccurrence of angina or myocardial
infarction3, 4. Contrary to expectation, though,
previous literature has demonstrated that better SVG patency does not
necessarily predict improved clinical outcomes. This finding is likely a
reflection of the multitude of intersecting factors that contribute to
patient-important clinical outcomes, including grafted territory, native
artery stenosis, and the function of additional grafts or
collaterals5.
Currently, a number of techniques are utilized in clinical practice for
SVG harvesting. These techniques include: the traditional open vein
harvesting (OVH), which involves a full-range open wound, the standard
bridging technique (SBT) and endoscopic vein harvesting (EVH), which
have been cultivated to reduce leg wound
complications6, and no-touch vein harvesting (NT),
which is purported to minimize mechanical trauma to the SVG. In this
issue of the Journal of Cardiac Surgery, Yokoyama and colleagues
conducted a network meta-analysis based on randomized controlled trials
and propensity-score matched studies to compare the impact of OVH, EVH
and NT on all-cause mortality, revascularization, and graft
failure7. The results demonstrated that the risk of
graft failure amongst patients receiving NT grafts was approximately
half of their counterparts in the EVH and OVH group. Importantly,
though, NT was not associated with lower all-cause mortality or
revascularization risk compared with the other techniques.
Interestingly, Vuong and colleagues similarly performed a network
meta-analysis based on randomized controlled trials to compare OVH, SBT,
EVH and NT8. Their results showed favorable, but not
significantly improved, graft patency in NT compared with OVH along with
identical mortality.
Since the introduction of NT grafts in 19969,
randomized controlled trials of this technique have demonstrated their
benefit at both short term and long term
follow-up,10-12 owing to its decreased vascular smooth
muscle activation.13 Contrastingly, the recent
randomized controlled trial comparing EVH and OVH did not show any
significant difference in outcomes14. Infection and
wound healing are the primary short-term issues related to NT up to 3
months postoperatively; indeed, higher risk of early infection at the
vein harvest site and leg wound discomfort have been identified in
patients with NT grafts compared with conventional
OVH15.
As Yokoyama and colleagues demonstrated in the present study, better
graft patency can be expected with utilization of the NT technique for
vein harvesting. Future investigations should aim to elucidate whether
better long-term clinical outcomes such as mortality, myocardial
infarction and revascularization can be achieved with the use of NT
veins. To this end, methodologies similar to those used to confirm the
superiority of radial artery grafts to vein grafts,16including large-scaled randomized controlled trials or patient-level
combined analysis, should be employed .