Recent studies support role of IVUS and FFR in advanced imaging

Volcano Corporation is highlighting studies presented at the recent American College of Cardiology (ACC) conference in New Orleans which suggested that more detailed imaging and diagnosis would be useful to optimize stent placement. The technologies that have the potential to assist include intravascular ultrasound (IVUS) and fractional flow reserve (FFR).

“Non-invasive imaging modalities, like CT angiography (CTA) and other screening tests, are very effective at guiding patients with coronary artery disease into the cath lab, and allowing interventional cardiologists to treat the patients that would clearly benefit from interventional therapy,” said John McB. Hodgson, MD, FSCAI, past president of the Society for Cardiovascular Angiography and Interventions, and chief of academic cardiology at St. Joseph’s Hospital and Medical Center in Phoenix, Ariz.

“However, these first pass screening tests also bring patients into the lab with less severe disease. These patients may also benefit from medical therapy alone and effective follow-up. In many cases, physicians are presented with the dilemma of balancing a positive CTA with a negative angiogram, then having to choose between intervention and medical therapy. Technologies like IVUS and FFR provide important objective measures of disease severity – essentially serving as the ‘tie breaker’ in these patients as the data supporting lesion significance related to IVUS and FFR measurements has been well studied.”

Data from the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) study showed that angioplasty and stenting did not reduce the risk of heart attack or death in the 2,300 patients who participated in the study with stable coronary disease versus medical therapy and lifestyle changes alone. Although controversial, the COURAGE data highlights a lack of clarity as to which patients benefit from stenting, and that angiography alone may not adequately or reliably triage these target patients.

Scott Huennekens, president and CEO of Volcano Corporation said that, “Angiography alone is severely limited in this regard as it can only diagnose vessel narrowing in 2D, and delivers no detail as to atherosclerotic plaque present or state of the disease at the narrowed, or the visually ‘clear’ parts of the artery. IVUS on the other hand provides a 3D slice of the diseased artery so physicians can quickly and accurately measure minimum lumen diameter, remodeled vessel size, and cross sectional flow area. Volcano’s proprietary VH IVUS technology also provides a snapshot of the tissue type along the length of the artery, again providing more detail to supplement angiography. This technique - used as part of the PROSPECT trial - may deliver important insights into what a vulnerable lesion looks like before a heart attack.”

An additional important observation of the COURAGE data was that 34 percent of patients in the stent group continued to experience angina 12 months after stent implantation. “This observation underlines the fact that in many cases we are either treating the wrong location because we didn’t use FFR to measure lesion severity, or we are placing the stent sub-optimally because we are not using IVUS to ensure full apposition and expansion post intervention. The data is starting to add up,” Huennekens said.

Gregg W. Stone, MD, of Columbia University Medical Center and the Cardiovascular Research Foundation, presented IVUS data from the Abbott SPIRIT III US Pivotal study where the Xience drug-eluting stent was randomized against Taxus. The data from the core lab showed that despite the importance of optimal stent placement as part of this key pivotal trial, of the 133 stents guided by angiography alone, stent mal-apposition was observed by IVUS in 34.4 percent in the Xience group and 25.6 percent in the Taxus group.  

“The prevalence of sub optimal drug-eluting stent deployment in patients guided by angiography in today’s clinical practice is staggering. The STLLR study sponsored by Johnson & Johnson using angiography guided DES treatment in 1,419 patients showed that current DES deployment techniques lead to some form of geographic miss in 66.5 percent of patients,” said Marco A. Costa, MD, PhD, FACC, FSCAI at the University of Florida, Shands Hospital in Jacksonville FL. “What is more alarming is that geographic miss has in turn negatively impacted patient outcomes, with significantly higher TLR, TVR, and myocardial infarction rates in patients where the stent was not placed properly. A re-examination of stent placement technique including the use of IVUS is certainly warranted.”