Intravascular ultrasound-guided stenting delivers improved outcomes for ACS patients

Using intravascular ultrasound (IVUS) to guide stent placement in patients with acute coronary syndrome (ACS) appears to reduce the 1-year risk of target vessel failure as compared with using angiography alone, according to the results of the IVUS-ACS study.

Over the 12-month follow-up, the primary endpoint of the composite of cardiac death, target vessel myocardial infarction, or clinically driven target vessel revascularization occurred less frequently in the IVUS arm than in the angiography arm (4.0 percent vs 7.3 percent), translating to a 45-percent reduction in the risk of target vessel failure (hazard ratio [HR], 0.55, 95 percent confidence interval [CI], 0.41–0.74). [Lancet 2024;doi:10.1016/S0140-6736(24)00282-4]

The risk reduction was driven by fewer target vessel myocardial infarctions and repeat revascularizations with IVUS guidance, with no significant between-group differences in the rates of survival and stent thrombosis, according to senior study author Prof Shao-Liang Chen of Nanjing Medical University in Nanjing, China, who reported the findings at ACC 2024.

The results for the primary endpoint were consistent across subgroups defined by age, sex, diabetes status, renal dysfunction, ACS type, stent length, presence of multivessel disease, and single versus dual antiplatelet therapy after 1 month, among others, Chen added.

He also pointed out that secondary endpoints such as target vessel failure without procedural myocardial infarction, individual components of the primary endpoint, and stent thrombosis collectively demonstrated the benefit of IVUS-guided over angiography-guided stenting.

“IVUS guidance was safe, although the procedures were longer and required slightly more contrast material—acceptable trade-offs for the lower risk of early and late major adverse cardiac events,” Chen said. “Adverse events during follow-up are especially reduced in patients for whom prespecified IVUS criteria for optimal stent implantation are achieved, including optimal stent expansion, lesion coverage, and freedom from major edge dissections.”

Improved stent placement accuracy

The findings from the present study are in line with the evidence from previous studies conducted largely in patients with chronic coronary syndrome, Chen noted. [Lancet 2024;403:824-837]

IVUS-guided PCI offers several advantages over an angiography-guided procedure, he said. One involves the implantation of larger and longer stents at higher pressures, leading to the achievement of a greater minimum stent area.

Additionally, IVUS guidance facilitates more precise identification of the landing zone, which helps minimize undertreatment of the reference segment disease, and enables identification and treatment of potential complications at the edges of the stent, Chen pointed out.

IVUS-ACS included 3,505 patients with ACS (median age 62 years) who were randomly assigned to undergo percutaneous coronary intervention (PCI) under IVUS guidance (n=1,753) or under angiography guidance (n=1,752). Of these, 73.7 percent were men, and 31.5 percent had type 2 diabetes. In terms of the presenting clinical syndrome, 40.7 percent of patients had unstable angina, 31.6 percent had NSTEMI (non-ST-elevation myocardial infarction), and 27.8 percent had STEMI.

Post-PCI quantitative coronary analysis showed that the median minimal lumen diameter was 2.76 mm in the IVUS arm versus 2.70 mm in the angiography arm (p=0.0007). The median diameter stenosis was 12.9 percent versus 14.0 percent (p=0.0005), respectively. In the IVUS arm, optimal postintervention intravascular ultrasound criteria were met in 79.9 percent of patients.