In a systematic review and meta-analysis, intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) was associated with a 33% relative risk (RR) reduction for cardiovascular death (the primary endpoint) compared to coronary angiography (CA) alone. (The individual study follow-up period ranged from 6 months to a maximum of 64 months.)
The paper, published in the Journal of the American Heart Association, also showed that adjunctive IVUS imaging was associated with a lower risk of secondary endpoints: post-procedural myocardial infarction (RR: 0.71), target lesion revascularization (RR: 0.81), and stent thrombosis (RR: 0.57), all reaching statistical significance, compared with CA alone.
Despite evidence supporting IVUS to optimize PCI, the adoption of intracoronary imaging to guide stent implantation remains low: 6.6% in the United States, according to data published in 2018. Surveys suggest that the low use is due in part to a perceived lack of clinical evidence to justify the increased cost and procedural time, but this new meta-analysis of 19 eligible studies with 27,637 patients demonstrates the value of seeing in 3-D for optimal stent implantation.
Since the inception of PCI decades ago, X-ray CA has been the standard imaging platform used to guide coronary intervention procedures. However, a major drawback of CA is that it relies on 2-dimensional projections to define the structure of complex 3-dimensional coronary artery lumens. This limitation can be overcome using high-resolution intracoronary imaging that offers detailed 3-dimensional intracoronary views of the vessel.
Fahed Darmoch, MD, of Beth Israel Deaconess Medical Center/Harvard School of Medicine, and colleagues write that IVUS-guided PCI offers more details about the coronary atherosclerotic plaque, vessel wall, and facilitated stent delivery, which subsequently improves outcomes. IVUS can identify plaque rupture, endothelial disruption, the presence of thrombus, and coronary artery dissection. It can also determine vessel diameter, plaque burden percentage, and minimal luminal area of intermediate coronary lesions; facilitate optimal stent sizing; and confirm stent apposition after PCI.
Time, Cost and Comfort
If the data are there, what is needed to increase the utilization of IVUS? M. Chadi Alraies, MD, of Wayne State University, Detroit, co-primary author on the study, told CRTonline, “Time should not be a limiting factor for using IVUS since it is for the patient’s best interest to have this imaging to lower TLR (target lesion revascularization) and stent thrombosis, which are associated with major adverse outcomes.”
Similarly, he said, cost should not be a factor because first, it is reimbursed and second, there is an opportunity to lower cost given that intravascular imaging significantly reduces stent thrombosis and TLR.
“On average there is a 10-minute increase in the procedure time if IVUS is used,” Alraies added, “which is technically not too much lab and staff time since you are getting optimal angiographic and imaging results” with clear clinical benefits.
A third factor may just be the No. 1 reason to explain the low use of intracoronary imaging: physician comfort with CA image interpretation. With decades of experience using coronary angiography, cath lab staff and physicians need to be educated on how to read IVUS imaging, Alraies said.
This analysis, along with study results published in a number of other published manuscripts, demonstrates that intracoronary imaging could be used considerably more often than it currently is.
Darmoch F, Alraies MC, Al-Khadra Y, et al. Intravascular Ultrasound Imaging–Guided Versus Coronary Angiography–Guided Percutaneous Coronary Intervention: A Systematic Review and Meta-Analysis. J Am Heart Assoc 2020;9:e013678. DOI: 10.1161/JAHA.119.013678 https://www.ahajournals.org/doi/10.1161/JAHA.119.013678
Smilowitz NR, Mohananey D, Razzouk L, Weisz G, Slater JN. Impact and trends of intravascular imaging in diagnostic coronary angiography and percutaneous coronary intervention in inpatients in the United States. Catheter Cardiovasc Interv 2018;92:E410-15. https://onlinelibrary.wiley.com/doi/abs/10.1002/ccd.27673