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Page 6 of 11 Flattery et al. Vessel Plus 2024;8:26 https://dx.doi.org/10.20517/2574-1209.2023.130

decrease in TVF (defined as a composite outcome of death from cardiac causes, target-vessel-related MI, or
clinically driven TVR) with the use of either intravascular imaging modality compared with angiography
alone (7.7% vs. 12.3%, P = 0.008). However, at three years, there was no difference in all-cause death, MI, or
overall revascularization. Prespecified subgroup analyses from RENOVATE-COMPLEX-PCI investigated
the outcomes in patients with specific lesions or clinical subtypes and demonstrated consistent significant
benefits in CTO interventions, left main coronary artery interventions, and in patients presenting with acute
coronary syndromes [13-15] .

Chronic total occlusions
Two 2015 studies described the impact of IVUS guidance on PCI of CTOs. The AIR-CTO multicenter study
performed in two centers in China evaluated lesion characteristics and clinical events two years after
[16]
randomizing 230 patients to PCI with DES using IVUS optimization vs. angiographic guidance alone .
Though they were able to demonstrate a reduction in late lumen loss (primary endpoint, defined as minimal
lumen diameter at one-year follow-up subtracted from minimal lumen diameter at the conclusion of index
procedure) at one year with IVUS guidance (0.21 vs. 0.46 mm, P = 0.025), there was no significant difference
in clinical events including all-cause death, cardiac death, MI, in-stent restenosis, TLR, or TVR. Conversely,
the CTO-IVUS study, conducted in 20 centers across South Korea, enrolled 402 patients with stable
coronary artery disease to compare IVUS with angiographic optimization after CTO PCI with DES. Here,
the authors did show a reduction in both cardiac death and the composite MACE outcome (defined as
[17]
cardiac death, MI, or TVR at 12 months; HR 0.35, P = 0.035), driven by decreased cardiac death and MI .
This difference may have been due to a larger sample size in the latter trial.

Long lesions
The utility of IVUS guidance for long lesions in the DES era was first assessed in the prespecified IVUS sub-
study of the 2013 multicenter RESET study, which was conducted at 26 sites in South Korea and evaluated
for differences in outcomes between PCI with DES of long lesions > 28 mm with IVUS guidance vs.
angiography alone in 543 patients . These investigators also did not demonstrate any differences in MACE
[18]
(defined as cardiovascular death, MI, or TVR) at one year.

Conversely, the 2015 IVUS-XPL trial enrolled 1400 clinically unselected patients at 20 sites in South Korea
with coronary lesions > 28 mm and also compared IVUS-guided PCI with DES vs. angiography alone. Here,
there was a reduction in MACE (defined as cardiac death, target lesion-related MI, or ischemia-driven TLR)
at both one-year (HR 0.48, P = 0.007) and five-year (HR 0.50, P = 0.001) follow-up [19,20] . The decrease in
event rates observed in this study was driven at both time points by decreased ischemia-driven TLR, with no
observed difference in cardiac death or MI.

Left main coronary artery PCI
The role of IVUS guidance in unprotected left main coronary artery stenting has been evaluated in two
RCTs. Tan et al. demonstrated in their 2015 single-center study of 123 patients in China that IVUS guidance
in unprotected left main coronary artery stenting in the elderly (age > 70) resulted in decreased MACE
(defined as death, non-fatal MI, or TLR) at two years (13.1% vs. 29.3%, P = 0.031), driven by decreased target
[21]
lesion revascularization . Liu et al. also reported in their 2019 Chinese single-center study of 336 patients
that IVUS guidance for unprotected left main coronary artery disease resulted in decreased incidence of
MACE (defined as cardiac death, MI, and TVR) at 12 months (13.2% vs. 21.9%, P = 0.031), driven in this
case by decreased cardiac death. All-cause mortality was not reported in this study, and there was no
difference in TVR .
[22]