A study of US Medicare patients undergoing percutaneous coronary intervention (PCI) has found that the use of intravascular ultrasound (IVUS) resulted in a lower long-term mortality, myocardial infarction (MI), and repeat revascularisation. However, the study by Amgad Mentias (University of Iowa Carver College of Medicine, Iowa City, USA) and colleagues, published in JACC: Cardiovascular Interventions, also found that overall use of IVUS guidance cases was low, having been used in just 5.6% of all PCI patients “with a wide variation of its use among different facilities”.
With an aim to uncover if IVUS use in real-world patients is associated with improved long-term outcomes of PCI, Mentias and colleagues studied Medicare patients who underwent PCI from January 2009 to December 2017. The main outcome of the study was long-term all-cause mortality, while secondary outcomes included hospitalisation for MI, and repeat revascularisation.
In total, the study population included 1,877,177 patients who underwent PCI during the study period, with IVUS used in 105,787 of these. The IVUS-guided PCI group had a higher prevalence of most comorbidities, Mentias and colleagues write, including heart failure (28.6% vs. 25.8%), prior coronary artery disease (22.8% vs. 21.8%), prior stroke (5.1% vs. 4.2%), chronic kidney disease (21.1% vs. 19.3%), chronic lung disease (22.9% vs. 20.9%), and pulmonary hypertension (4.8% vs. 3.9%;p<0.001 for all). The IVUS-guided PCI group also a had higher prevalence of complex PCI as evidenced by a higher number of stents placed, higher number of vessels treated, and higher number of bifurcation and chronic total occlusion lesions, Mentias and colleagues write.
Mentias and colleagues found that IVUS-guided PCI use was associated with a lower one-year mortality compared with PCI without IVUS (11.5% vs. 12.2%; p<0.001), as well as being associated with a lower rate of one-year MI (4.9% vs. 5.3%) and one-year repeat revascularisation (6% vs. 6.4%;p<0.001 for both).
The study team did identify an increasing trend of IVUS use throughout the course of the study, however this was described as only a modest change, increasing from 3% in 2009 to 6.9% in 2017 (p <0.01). Out of 1,934 PCI facilities, 1,073 (55.5%) did not use any IVUS or used IVUS in <1% of PCI procedures. Among the remaining 861 facilities, there was large variability in IVUS use (median, 5.7%; interquartile range [IQR]: 3.1% to 10.7%) with 360 (33.6%), 261 (24.3%), and 240 (22.4%) facilities using IVUS in 1% to 5% (moderate), 5% to 10% (frequent), and >10% (very frequent) of PCI procedures, respectively. Facilities with >5% IVUS use were more likely to be a teaching hospital (29% vs. 25%; p=0.05), and with higher bed capacity (median 302 beds vs. 279 beds; p=0.03).
Speaking to Cardiovascular News, Mentias offered his view on the potential barriers preventing greater uptake of IVUS-guided PCI in the USA. “I believe that there are several factors that are implicated in the low use of IVUS, such as lack of training or expertise in obtaining and interpreting the IVUS images, high cost of equipment with low reimbursement rates from payers, class of recommendation for use of IVUS in societal PCI guidelines, which has not been updated since 2011, lack of confidence that IVUS would improve or change hard end points such as recurrent MI or death, and time constraints in setting up the equipment during the procedure,” he said. It is important to note, Mentias added,that while the study showed an uptick in IVUS-use—from 3% in 2009 to 7% in 2012—this had subsequently plateaued at around 6.9% by 2017.
“To reverse this trend and to encourage more operators to adopt IVUS in PCI, especially complex PCI, Centers for Medicare & Medicaid Services (CMS) and insurance companies should recognise the importance of IVUS in improving outcomes and start a national discussion about the appropriate reimbursement model,” Mentias added. “Interventional cardiology fellowship programmes should be encouraged to make IVUS an important skill that new interventional trainees should learn and master in everyday use, this includes obtaining and interpretation of the images and acting on it. The professional societies should continue to enforce the role of intravascular imaging in PCI in educational meetings and practice guidelines. “
In an editorial comment accompanying the article in JACC: Cardiovascular Interventions Lorenz Raeber and Yasushi Ueki (Bern University Hospital, Bern, Switzerland) note that at present, international guidelines on myocardial revascularisation allocate a Class II recommendation for IVUS-guided PCI. “The reluctance toward a Class I recommendation may be explained by a currently limited (geographical) external validity, with a majority of RCTs [randomised controlled trials] conducted in Asia and an adoption rate that remains notably low except for in Korea and Japan,” they write.
As an observational study based on an administrative database, various limitations require consideration when interpreting the findings, they note, concluding: “Collectively, the body of evidence investigating the role of IVUS in PCI guidance has matured and data consistently suggest that imaging-guided PCI should become a mainstay of complex PCI procedures. To close the gap between evidence and clinical practice, reimbursement for imaging catheters, easy-to-use semi-automated software applications, and standardised and widespread education are crucial.”
Findings of the study have prompted a flurry of debate on social media, with Gregg Stone (Icahn School of Medicine, Mount Sinai, New York, USA) among the leading figures in interventional cardiology to pick up on the findings.
Speaking to Cardiovascular News, Stone commented: “Numerous clinical trials have demonstrated that intravascular imaging substantially improves clinical outcomes after stent implantation in complex coronary lesions. Despite these studies, multiple factors have resulted in use of intravascular imaging in a smaller than appropriate proportion of cases in the USA and Europe. These factors include suboptimal training in image interpretation and how to respond to the findings, increased procedural time, and lack of reimbursement.
“Conversely, in Japan where intravascular imaging is reimbursed and is a routine part of PCI procedures, intravascular imaging is used in >90% of cases. Hopefully, if the two ongoing large-scale trials of optical coherence tomography and IVUS compared with angiography alone are positive, the guidelines will elevate intravascular imaging to Class I, and training and reimbursement will improve. This should lead to an increase in the frequency of use of intravascular imaging during PCI, with better patient outcomes.”