Percutaneous coronary intervention (PCI) performed with intravascular ultrasound (IVUS) guidance results in a lower 1-year risk of target vessel failure compared with angiography guidance alone, new study results show. Observations from the IVUS-ACS study led researchers to believe this difference was driven by fewer target vessel myocardial infarctions, especially non-procedural infarctions after discharge. The research team also identified fewer repeat revascularization procedures in the IVUS as a contributing factor when compared with the angiography-guided group. “The results of the primary (intention-to-treat) analysis were consistent with those of the per-protocol analysis and across prespecified subgroups,” said the authors of the paper, which was simultaneously published online in The Lancet. “Both IVUS guidance and angiography guidance were safe and few procedural complications were noted. “No significant differences in cardiac death, all-cause death, or stent thrombosis were observed between the intravascular ultrasound and angiography guidance groups.” Trial first Findings gathered from the 3,505 patients enrolled into the two-stage, multicenter, randomized trial were presented Monday at the American College of Cardiology (ACC) Scientific Sessions 2024 in Atlanta. Presenting on behalf of research team member Gregg W. Stone, MD, and the IVUS-ACS investigators, Shao-Liang Chen, MD, said the primary endpoint occurred in 70 patients in the IVUS group (n=1,753) and 128 patients in the angiography group (n=1,752), with a Kaplan-Meier estimated rate of 4.0% in the IVUS group vs 7.3% in the angiography group (hazard ratio [HR] 0.55 [95% confidence interval (CI) 0.41-0.74]; p=0.0001). “Only three small dedicated RCTs of intravascular imaging-guided vs angiography-guided PCI in patients with ACS have been done (all with OCT [optical coherence tomography] guidance), with inconclusive results,” said Chen, from the Nanjing First Hospital, Nanjing Medical University in China. He added, “No dedicated RCT of IVUS-guided PCI vs angiography-guided PCI in patients with ACS has been performed.” Stent optimization Commenting on the study’s implications, Wijnand K. den Dekker, MD, PhD, from the University Medical Center Rotterdam in the Netherlands, said that while there were fewer target-vessel failures in the IVUS group, the most important message was that stent optimization was crucial in achieving the result. “The trial had IVUS-defined optimal stent implantation according to the ULTIMATE trial criteria for non-left main lesions and the EXCEL trial criteria for left main lesions in 79.9% of patients,” he said. “[This] is considerably higher than in the RENOVATE-COMPLEX-PCI study (55.5% for the IVUS group).” In his editorial, den Dekker also pointed out that patients with optimal IVUS-defined stent implantation had very low target-vessel failure rates (3.2%). Meanwhile patients with a suboptimal IVUS result had outcomes similar to the angiography-guided group (7.1% for suboptimal IVUS and 7-3% for angiography). This was also driven by fewer target-vessel myocardial infarctions and target-vessel revascularizations. Findings consistent “These findings are also in line with the RENOVATE-COMPLEX-PCI study,” he said. “Therefore, every operator needs to know what they see on IVUS, how to interpret the images, and how to act on it.” He went on to congratulate the research team for the study’s execution, singling out its completeness of follow-up at 1 year (>99.9%). “They were able to enroll a large sample in just over three years’ time despite the COVID-19 pandemic,” he said. “From 3710 consecutive patients with acute coronary syndrome, 3505 were enrolled in this study, an impressive 94.5%, perhaps due to a lack of competing studies at that time.” However, den Dekker questioned whether the findings could be generalized, as most patients were enrolled in China, with the site of the principal investigator being responsible for a large proportion (24.5%) of all enrolled patients. Concluding, den Dekker also thought that intravascular imaging guidance for PCI might get a class I recommendation soon with some more trials to come in both patients with ST elevation myocardial infarction and patients undergoing complex PCI. Study methodology The research team randomly assigned patients with ACS to IVUS-guided PCI or angiography-guided PCI at 58 centers in four countries in Asia and Europe. Out of the 3,505 ACS patients randomized, 1,753 were assigned to IVUS-guided PCI (with the Boston Scientific Corp. HD-IVUS OptiCross catheter and 1,752 to angiography-guided PCI. The mean patient age was 61.4 years, and 2,584 (73.7%) of the patients were male. Patients, research staff and all healthcare assessors outside of the catheterization laboratory were blinded to treatment assignment. The primary endpoint was target-vessel failure (TVF), a composite of cardiac death, target-vessel myocardial infarction, or clinically- driven target-vessel revascularization at one-year follow-up. Secondary endpoints included the components of TVF, stent thrombosis and all-cause death at one year Sources: Li X, Ge Z, Kan F, et al. Intravascular ultrasound-guided versus angiography-guided percutaneous coronary intervention in acute coronary syndromes (IVUS-ACS): a two-stage, multicenter, randomized trial. Lancet. 2024 Apr 8 (Article in press). den Dekker WK. Is intravascular imaging the future of percutaneous coronary intervention? Lancet. 2024 Apr 8 (Article in press). Photo Credit: Jason Wermers/CRTonline.org Photo Caption: Shao-Liang Chen, MD, presents results from the IVUS-ACS trial Monday at ACC.24 in Atlanta.