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Page 6 of 18 Browne et al. Vessel Plus 2024;8:19 https://dx.doi.org/10.20517/2574-1209.2023.126

[38]
incidence of graft failure was only 7% . This trend is also seen in our summary of trials with imaging
follow-up evaluating the common CABG conduits [Table 3]. The mean vein graft failure rate in trials
published before 2018 was 22.0% (1,996/9,077), compared with 8.6% (832/9,729) in trials published in 2018
[6]
or later. Notably, the overall 1-year rates of saphenous vein graft failure in our COMPASS CABG study
were 9.6% (221/2,292), and in the POPular CABG trial, they were 9.9% (94/954). These rates are
[17]
approximately half of those observed in the historic PREVENT IV or ROOBY trials, despite similar baseline
patient characteristics. A recent large trial of vein harvesting techniques reported even lower failure rates, at
[39]
5.1% (214/4,224) . It is important to note that this trend toward reduced rates of graft failure is specific to
saphenous veins and not arterial grafts. Falling rates of vein graft failure in contemporary trials may
contribute to the lack of superiority of RIMA compared with saphenous veins regarding both angiographic
and clinical outcomes.

Recent progress in cholesterol-lowering and antithrombotic therapies following CABG surgery may be an
important factor contributing to the downward trend in contemporary saphenous vein graft failure rates. In
a large randomized controlled trial, aggressive cholesterol lowering was found to reduce rates of saphenous
vein graft failure compared with moderate cholesterol lowering using lovastatin (6% [78/1,295] vs. 11%
[136/1,238]; P < 0.001) . Currently, lovastatin is commonly substituted with more potent medications such
[40]
as atorvastatin or rosuvastatin.

Regarding antithrombotic treatments, a recent individual patient meta-analysis of 4 RCTs (TAP-CABG ,
[41]
[19]
[16]
[17]
DACAB , TARGET , POPular CABG ) that included 1,316 patients and 1,668 saphenous vein grafts,
reported that dual antiplatelet therapy (DAPT) with ticagrelor compared with aspirin monotherapy was
associated with a lower rate of saphenous vein graft failure at 1 year after CABG surgery (11.2% [54/481] vs.
20.0% [99/494]; odds ratio: 0.51; 95%CI: 0.35-0.74) . Similarly, a recent network meta-analysis of 20 trials
[42]
and 4,803 patients undergoing CABG surgery reported that dual antiplatelet therapy, either combining
aspirin with ticagrelor (odds ratio: 0.50; 95%CI: 0.31-0.79) or aspirin with clopidogrel (odds ratio: 0.60;
95%CI: 0.42-0.86), proved to be more effective than aspirin alone in preventing saphenous vein graft
[43]
failure . Based on these studies, current North American guidelines recommend DAPT with aspirin and
ticagrelor or clopidogrel for 1 year to improve vein graft patency compared with aspirin alone in selected
[10]
CABG patients (Class 2b, level of evidence B-R) .

Skeletonized harvesting of IMA
The left and/or right internal mammary arteries (IMAs) are traditionally harvested as a pedicle, measuring 1
to 2 cm wide, which includes the artery, veins, fascia, and nerve [Figure 1]. Alternatively, the IMA may be
harvested using a more challenging technique known as skeletonization, which involves direct dissection
(i.e., removal of associated veins, fascia, and nerve). Skeletonized harvesting offers several advantages: it
results in a longer conduit (+3.7 cm) , enabling it to reach more distant targets and facilitating bilateral
[44]
IMA grafting. It also results in higher blood flow [44,45] and potentially fewer sternal infections [46,47] during
CABG surgery. However, the close dissection and ligation of branches directly on the IMA during
skeletonized harvesting may be associated with trauma to the IMA, thereby increasing the risk of thrombus
formation, laceration, and lumen narrowing that may lead to premature graft failure.

Although many surgeons routinely use the skeletonization technique for IMA grafts, the long-term effects
of skeletonized IMA on graft failure or clinical outcomes remain largely unknown. Few studies [45,48-52] have
compared pedicled and skeletonized harvesting techniques following cardiac surgery [Table 4]. Aside from
a small trial involving 200 patients, all other studies were non-randomized and conducted at centers that
favored skeletonized over pedicled harvesting in their practice (i.e., approximately two-thirds of patients