Virtual, Dynamic Coronary Map Cuts Contrast During PCI: DCR4Contrast

PARIS, France—Using a virtual coronary road-map overlay during angiography for complex PCI can significantly reduce the amount of iodinated contrast and the number of cineangiography runs, potentially reducing the risk of acute renal injury, a new randomized trial has found.

The technology itself requires a first contrast injection for the system to build the dynamic, motion-compensated, real-time view of the coronaries, then uses this to create an overlay that can be viewed on top of a 2D fluoroscopic image. Once superimposed, the live, brightly colored map of the coronary tree, moves in synch with the heart, allowing operators to navigate their guidewires without the need for another shot of dye.

The DCR4Contrast trial used the Philips Medical System’s proprietary Dynamic Coronary Roadmap (DCR). Javier Escaned, MD, PhD (Hospital Clínico San Carlos, Madrid, Spain), who presented the study here during a late-breaking trial session at EuroPCR 2023, told TCTMD that the technology has been available for more than half a decade, but is not widely in use.

“Interest in this approach of ultralow-contrast PCI has increased enormously, driven mainly because of the big shift in patient risk profile that is taking place because of demographics, but also because of the [increasing] survival of patients with cardiac and noncardiac diseases who do not have cardiac surgery options,” he said. “I think that what we are seeing more and more is that these types of techniques that are using less contrast may not only increase safety in terms of decreasing the chances of acute kidney injury, but also may contribute to improve the quality of PCI.”

EuroPCR Chair William Wijns, MD (Lambe Institute for Translational Medicine and CÚRAM, Galway, Ireland), speaking with TCTMD, said that there are “a number of colleagues who are appropriately aware of the danger of injecting too much contrast: it’s toxic. But too many are not.”

Escaned said the technology can be used in tandem with strategies like RenalGuard to reduce contrast exposure, as well as with intravascular imaging, where the mapping has “additional value” for performing coregistration with, for example, IVUS.

A Virtual Map

DCR4Contrast was performed in Belgium, Spain, Israel, and the United States, enrolling 371 patients that were randomized 1:1 to either DCR-guided PCI or conventional angiographic guidance.

To TCTMD, Escaned described the population as a mix of the type of patients in whom physicians might anticipate needing more contrast, but without being “exceptionally complex.” That means roughly one-third of patients had had a prior revascularization, 10-15% had chronic kidney disease, more than one-third had diabetes, and around 30% had had a prior MI; no chronic total occlusion patients were included.

In the 179 patients undergoing PCI with DCR, the virtual road map was associated with a significant reduction in contrast volume (90.8 vs 64.6; P < 0.001) as well as a significant reduction in cineangiograms (11.7 vs 8.7; P < 0.001), as compared with a similar number undergoing standard angiography.

In a prespecified analysis looking at contrast volume used according to tertiles of vessel Syntax score in the patient cohort, investigators found that while there was no difference in contrast use with no DCR versus DCR in the patients with the least complex coronary disease, there were significant differences in those in tertile 2 with more moderately complex disease (92.9 mL vs 62.9 mL; P < 0.001), and in patients in tertile 3 with the most complex CAD (114.2 mL vs 70.4 mL; P < 0.001).

“The benefit in terms of contrast reduction is proportional to the complexity of the PCI. This is what is clear,” Escaned told TCTMD.

Caveats and Mindset

The study was not powered to look at renal outcomes—a point alluded to by moderator Mpiko Ntsekhe, MD (Groote Schuur Hospital, Cape Town, South Africa), following Escaned’s presentation, calling it a “proof-of-concept trial.” Ntsekhe’s questions implied that, given the relatively modest difference in contrast volumes, a fairly sizeable trial might be needed to show a meaningful clinical benefit.

Moreover, operators, of course, were not blinded in the trial, meaning that those randomized to DCR technology might have been especially cautious in their use of contrast, something Escaned acknowledged, could not be controlled for in the study design.

“At the end of the day, obviously, from an ethical perspective, I think that everyone wanted to make sure that the procedure had proper results, and . . . wanted to be reassured that they had good outcomes,” he told TCTMD. That would prevent them from either withholding contrast in the DCR arm if they felt they needed that information and, in the conventional angiography arm, from overusing contrast in the conventional angiography arm.

While the technology has been commercially available for some time, Escaned said the evidence supporting its use has been scant. He hopes DCR4Contrast, as the first international, randomized, multicenter study, will persuade operators to think, in every case, about how to reduce their contrast use, and inspire them to do so not just for patients with renal disease, but for older patients, more complex CAD patients, patients with iatrogenic dissections, as well as those presenting with cardiogenic shock or resuscitated arrest.

This requires a “change in mindset,” he said. “We are moving away from what was foundational, so to speak, 40 years ago with PCI—which is the way that everyone learned to do PCI, relying on contrast opacification—to understanding that at least for large segments of the PCI procedure, that you do not need that, and you can actually achieve a better procedure.”

Elaborating on that during his presentation, Escaned characterized DCR “one technique that contributes further to this idea of relying less on contrast injections and having supporting tools, intracoronary imaging, dynamic coronary ‘road mapping,’ [and] display of the CT angiogram in front of you that may help you to guide the intervention without the use of contrast.”

Mamas Mamas, BMBCh, DPhil (Keele University, Stoke-on-Trent, England), senior clinical editor at TCTMD, said that he uses the technology in most of his elective procedures, pointing out that it is not as useful a tool during acute MI, given the need for emergent diagnostic angiography. In the elective setting, operators will have already decided on the optimal view for which they’ll need their road map.

“I think this is useful, particularly in more complex PCI procedures where the use of contrast is likely to be much greater,” Mamas said, adding that the benefits would be particularly evident in procedures using IVUS.

Wijns believes it’s largely a question of breaking bad habits.

“We have this [need to] check-check-check . . . to just press the button, because that’s how we were trained. You do have to do a very good contrast injection at the very beginning and at the end, because you’re going to do the measurements on that good contrast injection, whether it’s QFR or something similar. . . . But then, in between, reducing your contrast really has an impact and that’s the impact that is underestimated,” Wijns said. “In my mind, I think once you’ve seen it, that this is possible, you say, ‘Wow, I’m going to do this now and teach it to the fellows.’”