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In patients with acute coronary syndrome (ACS), intravascular ultrasound (IVUS)-guided implantation of a drug-eluting stent improved outcomes compared with angiography guidance alone.

"Our study included all different kinds of complex lesions," Shao-Liang Chen, MD, of the Nanjing Medical University and Nanjing First Hospital, Nanjing, China, told attendees at the American College of Cardiology (ACC) Scientific Session 2024 on April 8. The primary endpoint was the one-year composite of target vessel failure (TVF), including cardiac death, target vessel myocardial infarction (TVMI) and clinically driven target vessel revascularization (TVR). 

"We found that the TVF endpoint was 7.3% in the angiography-guided group compared to only 4.0% in the IVUS-guided group, which is a 45% reduction in the hazard rate," he said.

"Secondary endpoints were TVF without procedural MI, individual components of the primary endpoint, and stent thrombosis," he added. "All the results demonstrated the benefit of IVUS guidance over angiography guidance."

The IVUS-ACS study findings were simultaneously published online in The Lancet.

Chen's co-study chair, Gregg W. Stone MD, director of Academic Affairs for the Mount Sinai Heart Health System and a professor of cardiology and population health sciences and policy at the Icahn School of Medicine at Mount Sinai in New York City, added in an interview with theheart.org | Medscape Cardiology that the team's related meta-analysis was recently published in The Lancet.

"That study showed that intravascular imaging guidance of a drug-eluting stent with IVUS or optical coherence tomography reduces mortality, acute MI, repeat revascularization and stent thrombosis compared to angiography-guidance alone," Stone said. 

"After the current study, which is the largest randomized trial ever of intravascular imaging guidance in any setting, this should be a class I indication in the guidelines," he added. "But it's still only class IIA, and it's still done by a minority of people because of cost and training issues."

TVF Lower With IVUS

Chen and colleagues randomized 3505 patients (1:1) presenting with an ACS at 58 centers in China, Italy, Pakistan, and the United Kingdom to IVUS- or angiography-guided PCI. 

The median age was 62 years, 74%, were men, and 88% were Chinese. About 40% had unstable angina, about 31% n on-ST-elevation MI (STEMI), and about 28% STEMI.

The original protocol specified inclusion of patients presenting just before the stenting procedure, but it was amended on March 28, 2021, because of the pandemic's quarantine policies to allow inclusion of patients presenting up to 30 days before randomization.

The primary endpoint was TVF, a composite of cardiac death, TVMI, or clinically driven TVR, at 1 year after randomization. A primary endpoint event occurred in 70 patients in the IVUS group and 128 in the angiography group (4.0% vs 7.3%; hazard ratio 0.55), largely driven by reductions in TVMI or TVR. 

No significant between-group differences were seen in all-cause death, stent thrombosis, or safety endpoints. Adverse events during follow-up were especially reduced in patients for whom prespecified intravascular-guided PCI for optimal stent implantation were achieved — including optimal stent expansion, lesion coverage, and lack of major edge dissections.

Considered in light of previous studies, the authors write, "these data show that intravascular ultrasound-guided percutaneous coronary intervention improves clinical outcomes, including measures of both safety and effectiveness, across the spectrum of coronary artery disease and patient presentations (acute or nonacute coronary syndrome)."

This same population underwent a second randomization to look at post-PCI antiplatelet regimens, also reported at this meeting as the ULTIMATE-DAPT trial. 

'Definitive Benefits'

Commenting on the IVUS-ACS study for theheart.org | Medscape Cardiology, Aakriti Gupta, MD, an interventional cardiologist and assistant professor of cardiology with the Smidt Heart Institute at Cedars-Sinai, Los Angeles, said, "This trial focused specifically on acute coronary syndromes where there is a concern regarding increasing risk of distal embolism and slow-flow phenomenon with the imaging catheter in a hyperinflammatory and thrombotic milieu." 

"However, I have felt these concerns to be minimal in my clinical practice, where I utilize IVUS imaging in 95% of ACS cases."

"It is reassuring to see that there was no difference in effect sizes when stratified by types of ACS," said Gupta, who was not involved in the study. However, given that the study protocol was amended to allow for enrollment up to 30 days prior to ACS presentation, "it would be informative to know what proportion of patients were not included at the time of the index ACS," she said. 

"Patients who were included after the index ACS event may be more similar to the stable coronary disease population," she explained. "If a significant proportion of patients were randomized after the index event, then it will be difficult to discern effect size in a true ACS population."

Nevertheless, she said, "IVUS-ACS further underscores the definitive benefits of routine intravascular imaging for patients, including those with ACS. Interventional cardiologists should consider intravascular imaging as a standard component of their therapeutic arsenal for the management of acute coronary events."

In a linked commentary in The Lancet, Wijnand K. den Dekker, MD, University Medical Center Rotterdam, Netherlands, wrote, "It seems that intravascular imaging guidance for percutaneous coronary intervention 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 percutaneous coronary intervention. 

"Until then, operators would benefit from getting familiar with intravascular imaging-guided percutaneous coronary intervention."

The trial was funded by the Chinese Society of Cardiology, the National Natural Scientific Foundation of China and the Jiangsu Provincial & Nanjing Municipal Clinical Trial Project. Stents were supplied by Medtronic and Microport Medical, and antiplatelet agents were supplied by Yung Shin. Chen received speaker honoraria from Microport, Pulnovo, Boston International Scientific, Medtronic, Sanofi, and BioMed, and grants from the National Scientific Foundation of China, Jiangsu Provincial & Nanjing Municipal Clinical Trial Project. Stone reported fees from multiple pharmaceutical and biotech companies. Gupta reported receiving research grants from Boston Scientific. 

Marilynn Larkin, MA, is an award-winning medical writer and editor whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, The Lancet (where she was a contributing editor), and Reuters Health.