Page 191 - Read Online

Harik et al. Vessel Plus 2023;7:30 https://dx.doi.org/10.20517/2574-1209.2023.124 Page 3 of 16

CABG GRAFT FAILURE
While the majority of the data on graft failure, or graft occlusion that prevents blood flow to the myocardial
territory targeted for revascularization, has been from older observational studies that are subject to
confounders and biases , there is recently available evidence from contemporary CABG trials. In an
[1,2]
analysis of the Radial Artery Database International Alliance (RADIAL) database pooling patient data from
six randomized CABG trials (1,091 pooled patients and 2,281 grafts) with mean angiographic follow-up of
[11]
5.4 ± 2.4 years , the SVG had a 17.5% occlusion rate. In comparison, the occlusion rate was 2.3% for the
LITA ; all studied LITAs were grafted to the LAD. The occlusion rate of the RA was 9.4% , including only
[11]
[11]
RAs that were grafted to the non-LAD distribution. The occlusion rate of the RITA was 13.5% , again,
[11]
including only RITAs that were grafted to the non-LAD distribution.
A network meta-analysis of 18 randomized clinical trials (RCTs) including 6,543 patients and 8,272 grafts
with 3.5-year mean angiographic follow-up, the conventionally harvested SVG had a pooled patency rate of
86.3% (95% confidence interval [CI] 81.2-90.2), the no-touch SVG had a pooled patency rate of 91.4%
(95%CI: 87.3-94.3), the RA had a pooled patency rate of 94.1% (95%CI: 90.0-97.6), the RITA had a pooled
patency rate of 89.2% (95%CI: 71.2-96.5), and the RGEA had a pooled patency rate of 61.2%
(95%CI: 52.2-69.4) .
[12]

The Radial Artery Patency and Clinical Outcomes (RAPCO) study compared RA outcomes and patency at
10-year follow-up in two trials: one comparing the RA and RITA and one comparing the RA and SVG. The
10-year analysis found that RA patency was 89% and RITA patency was 80% in the RA vs. RITA
comparison (graft failure hazard ratio [HR] 0.45, 95%CI: 0.23-0.88), and RA patency was 85% and SVG
[13]
patency was 71% for the RA vs. SVG comparison (graft failure HR 0.40, 95%CI: 0.15-1.00) .
Relationship between clinical outcomes and graft patency
Graft patency has historically been considered an important factor influencing graft choice, largely due to
the accepted link between graft patency and clinical outcomes. Most published studies have demonstrated
an association between graft failure and non-fatal clinical events, yet this association was derived from older
observational studies that did not have protocolized, systematic graft imaging and that are also subject to
selection and attrition biases [1,2,14] . A recent individual patient data meta-analysis by Gaudino et al. including
seven CABG trials with per-protocol imaging, 4,413 patients, and 13,163 grafts (8,740 SVGs and 4,423
arterial grafts), examined the relationship of graft failure and clinical outcomes and found that graft failure
was associated with an increased risk of the composite of myocardial infarction or repeat revascularization,
both up until first imaging assessment at a median timepoint of 1.02 years (adjusted odds ratio [OR] 3.98,
95%CI: 3.54-4.47; P < 0.001) and beyond (adjusted OR 2.59, 95%CI: 1.86-3.62; P < 0.001) . Graft failure was
[15]
also associated with all-cause death after the first imaging assessment (adjusted OR 2.79. 95%CI: 2.01-3.89;
P < 0.001). This analysis confirmed that in current practice, there is a strong association between graft
failure and adverse cardiac events [Table 1]. In addition, Gaudino et al. found that both arterial (adjusted
OR 2.09, 95%CI: 1.33-3.28; P = 0.001) and vein (adjusted OR 1.97, 95%CI: 1.33-2.91, P = 0.001) graft failure
were associated with an increased risk of the composite of myocardial infarction or repeat revascularization
before first imaging assessment . However, some contemporary studies, including The Impact of
[15]
[16]
Preoperative FFR on Arterial Bypass Graft Function (IMPAG) trial , have suggested that lower degrees of
preoperative native coronary artery stenosis may lead to chronic native competitive flow and thus
asymptomatic arterial graft failure [16,17] . At angiographic six-month follow-up in the 64 IMPAG patients
receiving arterial grafts, there was an association between preoperative fractional flow reserve (FFR) of
≥ 0.78 and better graft functionality .
[16]