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Page 4 of 9 Dewantoro et al. Vessel Plus 2018;2:20 I http://dx.doi.org/10.20517/2574-1209.2018.50

Another randomized trial that aims at comparing single and bilateral ITA conduits has been used to pro-
vide data for the outcome of VCABG. The data taken from this trial will be the outcome for the single ITA
conduit to reduce the bias provided by using both ITA in term of sternal healing and long-term patency of
graft. In this trial, there were 1554 patients with average age of 63.5 years that underwent single ITA graft
plus supplementary venous or arterial conduits. The 5-year outcome found from patients follow up in term
of MACCE is 198 (12.7%), all-cause mortality was 8.4%, total revascularization rate was 6.6% and stroke
incidence was 3.2%. As mentioned in the report, even though this trial involved statistical corrections and
propensity matching, there is still chance of bias in terms of patient and operator selection. In this trial, it
was mentioned that a post-hoc analysis of the SYNTAX trial compared 5-year outcomes in 456 patients who
received a second arterial conduit with those in 963 patients who underwent single ITA grafting with ad-
ditional vein grafts, in which propensity score adjustment was done, showing that MACCE were 23.3% in
arterial group and 21.4% in venous group (P = 0.04). However, the all-cause mortality was 9.1% in the arte-
rial group and 9.5% in the venous group (P = 0.19) [11,14] . From this analysis, single ITA with supplementary
vein graft has better MACCE outcome as compared to total arterial revascularization. However, the starting
number of arterial group is half of that venous group, showing a tighter population choice which lead to se-
lection bias, even though propensity score has been done. On the other hand, the venous group done worse
in term of all-cause mortality, although no differences were found with regards to cardiovascular mortality.

Special population: patients with left main disease
Left main CAD is the highest-risk lesion subset of ischemic heart disease and has traditionally been an indi-
cation for coronary artery bypass grafting (CABG). Significant (defined as a greater than 50% angiographic
narrowing) left main disease is found in 4 to 6% of all patients who undergo coronary arteriography, and it
is associated with multivessel CAD about 70% of the time. While trying to find outcome analysis available
to show the result of total arterial CABG in left main disease, it has shown to be a challenge as there are not
[15]
much of such data available. The closest data is that from RAPCO study . In this study, radial artery was
compared to either right ITA or saphenous vein and patency was then compared. The group of patients in
which the result is being used here, is that of 140 patients with an average age of 60.1 years old with total
arterial revascularization of their cardiac arteries. The only available results are all cause of mortality (2%)
[15]
and revascularization with PCI (2%). RAPCO study is a prospective, randomized, single-center trial . Even
though the study was able to provide criteria in order to reduce selection bias due to its prospective nature,
but by being a single-center trial, it may not necessarily representative of the population in general [Table 1].

A retrospective multicenter analysis comparing TACABG to VCABG, has shown that TACABG is associated
[4]
with higher peri-operative as well as long-term survival . In the study, the Kaplan-Meier survival within 5
years for TACABG group is 91.3% as compared to 90.1% in the VCABG patients (P < 0.01). Although it may
seem that the survival rates are not significantly different, when compared to those of the 10 years, there
seems to be a widening gap between the two groups, in which the survival for TACABG is 85.4% while
[4]
VCABG is 81.2% (P < 0.01) . This study should not show a significant selection bias due to propensity score
matching. Although, its nature of being a retrospective analysis may lead to some unmodifiable selection
bias.

DISCUSSION
Evidence from the literature show that arterial conduits have better prognosis as compared to venous con-
duits when used in the revascularization of coronary arteries. However, there are certain aspects of venous
conduits that are non-inferior than arterial ones.

Firstly, in term of preparation, there is a requirement to check that any of the vessels being used are intact
and of satisfactory quality to provide the best outcome from undergoing CABG. While it is required to
check for the patency of ulnar artery when radial artery is being used, there seem to be no requirement to