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Page 8 of 11 Raja. Vessel Plus 2019;3:23 I http://dx.doi.org/10.20517/2574-1209.2019.05

The single most important and perhaps greatest issue in encouraging adoption of TAR has to be a
consideration of data quality. As it has occurred in other areas to which changes to long-standing and
previously well-established practices have been recommended, skepticism may well override reason in
[42]
the absence of “gold standard” prospective RCTs . The arena of TAR unfortunately has not enjoyed the
benefit of great amounts of such data. As a consequence, even cursory reviews of the available retrospective
data readily identify “easy targets” of dissonant data typical of retrospective studies that offer a ready
[42]
opportunity for disproving the conclusions of these studies .

CONTROVERSIES
Are three arterial grafts better than two?
Whether the addition of a third arterial conduit (mainly radial artery) to BIMA is associated with better
survival than BIMA plus SVGs remains a controversial area, with published literature reporting conflicting
[50]
results [41,43-51] [Table 2]. Luthra et al. in a retrospective, single-center, propensity-matched study compared
the impact of a third arterial or venous conduit to the right circulation on early and intermediate survival
after CABG in patients with at least two arterial grafts to the left circulation. They failed to demonstrate
a significant difference in early or intermediate survival in the propensity-matched groups (venous vs.
arterial, 99.2% vs. 99.2%; P = 1.000 at 1 year; 85.2% vs. 88.8%; P = 0.248 at 5 years and 69.2% vs. 88.8%; P =
[51]
0.297 at 7 years). Similarly, Formica and associates comparing the use of radial artery as a third arterial
conduit versus SVG failed to show long-term survival benefit of addition of third arterial graft to BIMA.
One possible explanation for these contradictory findings is that the survival benefit provided by the use
of a third arterial graft is lower when compared with the use of the first or second arterial conduit as
most of these single-institutional studies, with small sample sizes, were underpowered to detect moderate
[52]
differences in survival . Interestingly, a meta-analysis of these studies reported that the use of a third
arterial graft is not associated with an increase in the operative risk but rather with a 24% survival benefit
[52]
at a mean follow-up of 77.9 months . Clearly, there is a need for an RCT, preferably multi-institutional,
with a large sample size to address this controversy.

Are all configurations of total arterial grafting equal?
The optimal conduit choice and configuration in achieving TAR remains controversial, with uncertainty
[53]
regarding the individual prognostic impact of IMAs and supplemental arteries. Shi and associates , in
a multicentre propensity matched study showed that all configurations of TAR are not equivalent. They
compared long-term survival after TAR using single IMA and BIMA supplemented with radial arteries
and reported that the use of BIMA as in situ or free conduits is associated with greater survival and seems
to offer a prognostic advantage over the use of only a single IMA supplemented by radial arteries. Similar
[54]
findings were reported by Navia and colleagues .
The recently published 10-year final analysis of the Arterial Revascularization Trial (ART), comparing
single IMA with BIMA, failed to show significant between-group difference in the rate of death from any
[55]
cause in the intention-to-treat analysis . One plausible explanation offered by the authors for this outcome
was that 14% of the patients who had been randomly assigned to the BIMA group actually underwent
single IMA grafting, and 22% of those who had been randomly assigned to the single IMA group also
received a second arterial graft in the form of a radial artery graft. The use of radial artery grafts in ART
may be a key confounder, because it is likely to preferentially benefit the single IMA group by the addition
of an arterial graft to the second most important coronary artery. When data from patients were analyzed
according to the actual receipt of two or more arterial grafts, as compared with a single arterial graft (the
as-treated analysis), there appeared to be a meaningfuifference in mortality in favor of multiple arterial
[53]
grafts . It is anticipated that the Randomized Comparison of the Clinical Outcome of Single versus
Multiple Arterial Grafts (ROMA) trial will address this controversy.
[56]