BARCELONA, Spain — A blurred picture of cardiovascular imaging emerged during EuroPCR 2008, not unlike the angiograms that remain the reference among cardiac clinicians for both diagnosis and navigation.
For the 11,000 percutaneous cardiac interventionalists gathered here this week for the 18th annual conference organized by the European Association for Percutaneous Cardiovascular Interventions, the out-of-focus black-and-white images transmitted from live cases at 17 different centers or from recorded case studies have become the accepted view of the heart.
Big-screen monitors scattered throughout the conference center always drew a crowd of clinicians like so many sport fans whenever the image switched from Powerpoint slides or talking heads to the telltale gray backdrop that signaled a coronary intervention with guide wires snaking through clogged arteries to deploy stents.
The focus on bifurcated stenting on the third day of the conference forced remote viewing for most participants, as the conference salon was packed to capacity and closed, sending the spill over audience to monitors located in corridors and the exhibition space.
There was markedly less enthusiasm at EuroPCR, however, for the relatively new view offered for heart procedures using intravascular ultrasound (IVUS), despite the fact that these images are coming from the interior of the vessel and show the precise placement of a stent, the effectiveness of the deployment of expanded struts, and are capable of distinguishing plaque and the exact degree of vessel occlusion.
The reason, according to a polling of cardiac interventionalists ahead of this year's meeting, is that the fuzzy ultrasound images are far from intuitive, notoriously hard to understand even among the initiated, and that even five years after being introduced into cath labs, only a minority of practitioners are comfortable looking at the images.
The polling of practitioners was carried out ahead of a symposium, "Controversies in Coronary Intravascular Imaging," with debate centered around the question as to whether IVUS guidance has an impact on patient outcomes.
Even the advocate in favor of IVUS for the debate, Gary Mintz, MD, of the Cardiovascular Research Foundation (Washington), acknowledged the current ultrasound images are not easy to interpret, that there is not a quick or easy way for an interventionalist to learn how to interpret the images, and further, the images "are plagued by artifacts and quality issues."
Among the top reasons given in the EuroPCR poll for not using IVUS in everyday practice, more than half of clinicians said they cannot afford it and a third said it takes too much time.
These obstacles explain in part the slow market penetration for IVUS and the continuing controversy over its benefits.
In the U.S., where percutaneous cardiac interventions (PCI) have stabilized between 250,000 to 300,000 procedures each year, over the past five years the penetration of IVUS has moved slowly from 8% to just 15% today.
By contrast, Mintz said, in Japan usage approaches 70%, which he attributed to the favorable reimbursement scheme for IVUS.
The sponsor of the "Controversies" symposium, Volcano (San Diego), confirms this slow uptake in the world's biggest medical market reporting more than half of its revenues from sales of IVUS are currently coming from outside the U.S. and that Japan is the single biggest market for the device.
Taking the case against IVUS in the debate was Jean Marco, MD, the founder of the EuroPCR event and the program director, in a rare display of overt opposition to any advance in the practice.
Saying that robust evidence supporting IVUS has not been developed, he added that 30,000 patients would be required to adequately power a trial leading to the kind of evidence necessary to support the hypothesis that routine use of IVUS should be mandatory to optimize clinical outcomes according to European Society of Cardiology guidelines on PCI.
Marco said he agreed that IVUS increases understanding of PCI as a research and teaching tool, and that IVUS guidance may improve outcomes of PCI, especially in left main stenting and should be considered as an optional companion in clinical practice.
"Yet routine IVUS guidance of coronary stent implantation is not supported by a critical reappraisal of the available evidence," he said.
Volcano sought to provoke controversy with the symposium, but may not have been prepared for the eruption from one of the leading influencers in the field.