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Browne et al. Vessel Plus 2024;8:19 https://dx.doi.org/10.20517/2574-1209.2023.126 Page 13 of 18

results. However, we caution the use of institutional case volumes as a surrogate for individual surgeon
experience.

In addition, we speculate that the observed suboptimal rates of RIMA graft failure could be due to the study
settings. Single-center studies, which often report positive RIMA results, may be biased toward positive
outcomes as they reflect the performance of a small, identifiable group of experienced surgeons. On the
other hand, multi-center trials, which frequently report neutral or negative RIMA results, may present more
balanced outcomes as they involve numerous surgeons of unknown experience across various institutions.

In order to improve the utilization of MAG, many surgeons have advocated for increased exposure to MAG
techniques during cardiothoracic surgery training . Single-center observational evidence suggests that
[66]
adequately supervised trainees can perform MAG without compromising patient safety and long-term
survival [67,68] . Since surgical training policies are often guided by high-quality clinical evidence, the pursuit of
robust evidence of benefit and safety, from ongoing and future large pragmatic trials with long-term
angiography and clinical follow-up, could not only foster wider acceptance but also address educational
barriers impeding greater utilization of MAG.

Total arterial grafting and sex-based differences in MAG
The proposed benefits of MAG or TAG over SAG for improving patient outcomes are based on
observational studies and have yet to be clearly established. Compared with SAG, MAG was associated with
a numerically lower risk of 10-year all-cause mortality (hazard ratio, 0.84; 95%CI: 0.69-1.03) and TAG was
associated with an even lower risk (hazard ratio, 0.68; 95%CI: 0.48-0.96), suggestive of an incremental
benefit of arterial grafting in a recent post hoc analysis of 1,084 patients from of the ART trial . Overall,
[69]
both MAG and TAG were associated with a lower risk of the composite of all-cause mortality, myocardial
infarction, stroke, or revascularization (MAG vs. SAG; hazard ratio, 0.82; 95%CI: 0.69-0.96 and TAG vs.
SAG; hazard ratio, 0.71; 95%CI: 0.53-0.94).

Interestingly, in a retrospective analysis of New York’s Cardiac Surgery Reporting System database that
included 63,402 patients undergoing CABG surgery from 2005 to 2014, all-cause mortality was lower in
men who underwent MAG compared with SAG (hazard ratio, 0.80; 95%CI: 0.73-0.87), but not women
(hazard ratio, 0.99; 95%CI: 0.84-1.15), suggesting sex-based differences in outcomes after MAG that warrant
[70]
further investigation .
The ROMA trial
The Randomized comparison of the clinical Outcome of single versus Multiple Arterial grafts (ROMA) trial
is currently evaluating MAG vs. SAG for reducing major adverse cardiovascular or cerebrovascular events
(MACCEs) in 4,300 patients undergoing isolated CABG surgery (ClinicalTrial.gov number,
[71]
NCT03217006) . Eligible patients are randomly assigned to receive SAG (one IMA-to-LAD graft with all
additional grafts using saphenous veins) or MAG (one IMA-to-LAD graft and either a second IMA or RA
grafted to the main target vessel of the lateral wall with additional grafts using saphenous vein or arterial
conduits) [Figure 3]. The primary outcome is a composite of all-cause mortality, stroke, post-discharge
myocardial infarction, or repeat revascularization reported as survival curves after the accrual of 845 events.
The secondary outcome is all-cause mortality after 631 events.

In the ROMA trial, half of the MAG patients are expected to receive a secondary RIMA grafted to the lateral
wall. In the context of the poor RIMA results summarized in this review, it is possible that poor RIMA
performance may potentially mask a true benefit of MAG over SAG, resulting in an overall neutral trial (i.e.,