Infraredx, Inc., a cardiovascular imaging company pioneering the personalized diagnosis of coronary artery disease, today announced results from an independent, prospective outcomes study published in the Journal of the American College of Cardiology (JACC). The study evaluated the ability of intravascular near-infrared spectroscopy (NIRS) to identify lipid core-containing plaques, which are believed to be implicated in most heart attacks, as a means to predict the risk of future major adverse cardiac and cerebrovascular events (MACCE). In the study, patients who presented with symptoms associated with limited blood supply to the heart also underwent NIRS imaging to evaluate the Lipid Core Burden Index (LCBI) in an artery that was not directly implicated in causing their symptoms. The results, which were published online on Dec. 8 and will appear in the Dec. 16 print edition of JACC, demonstrated that patients with an LCBI > 43 in a non-culprit artery had a fourfold risk of MACCE, such as heart attack or stroke, within the following year. In addition, the study concluded that non-culprit vessel LCBI reflects vascular vulnerability of the larger coronary tree.
Lipid-core plaque is a type of fatty coronary artery plaque suspected to be prone to rupture, which leads to the formation of blood clots that can cause heart attacks. Only NIRS can detect lipid-core plaque and provide a quantitative measurement in the form of an LCBI. Intravascular NIRS is commercially available through the TVC Imaging System™ (Infraredx, Inc.), which is the only FDA-cleared dual-modality imaging system capable of rapidly, specifically and reliably identifying lipid-core plaques using NIRS and providing vessel structure information using enhanced intravascular ultrasound (IVUS).
"Our findings suggest that the use of NIRS imaging to identify and quantify lipid-core plaque in the non-culprit arteries, which would otherwise remain undetected by coronary angiography, could be a viable tool to assess the vascular vulnerability of the larger coronary tree," said Rohit M. Oemrawsingh, M.D., M.Sc, the study's first author at the Thoraxcenter, Department of Cardiology, Erasmus MC, Rotterdam, the Netherlands. "The findings of our investigator-initiated, prospective study seem promising, but external validation, preferably in a larger sample size, is a fundamental prerequisite before any of our conclusions might be considered for possible future clinical implications. The Lipid-Rich Plaque Study and PROSPECT II / ABSORB Study may answer the outstanding academic questions."
The ATHEROREMO-NIRS Study, a sub-study of the European Collaborative Project on Inflammation and Vascular Wall Remodeling in Atherosclerosis (ATHEROREMO), is a prospective, single-center, observational study that enrolled 203 patients referred for coronary angiography due to stable angina (chest pain) or an acute coronary syndrome (ACS), a combination of symptoms resulting from the blockage of blood supply to the heart. NIRS imaging was performed and an LCBI measurement was obtained for a pre-defined segment of a non-culprit coronary artery that was at least 40 mm in length and with < 50 percent stenosis confirmed by angiography. The primary endpoint was the incidence of MACCE, defined as all-cause mortality, non-fatal ACS, stroke and unplanned coronary revascularization during one-year follow-up. MACCE not related to the culprit lesion - the site treated during the index procedure - occurred in 21 patients (10.4 percent). In addition, regression analysis demonstrated that men, patients with a history of hypercholesterolemia, stroke or peripheral artery disease had higher LCBI values.
"This study by Oemrawsingh and colleagues is an important step forward to support the use of direct measurement of lipid in the coronary artery wall to determine the risk of future coronary events," said James Muller, M.D., co-founder and chief medical officer of Infraredx. "The identification of patients with an elevated risk of a new adverse coronary event in the year post-PCI, despite receiving standard medical therapy, may inform future studies of novel pharmaceutical agents."
Dr. Muller added: "These findings also provide support for several large-scale, longitudinal studies seeking to identify vulnerable patients, as demonstrated in the present study, and vulnerable plaques. Two studies currently in progress, the Lipid-Rich Plaque Study and the PROSPECT II/ABSORB Study, and the Veterans Affairs Oracle Study, slated to launch imminently, will all utilize NIRS-IVUS imaging with our TVC Imaging System to evaluate vessel structure and plaque composition to test the vulnerable plaque and vulnerable patient hypotheses. We believe that successful outcomes in these prediction studies may lead to studies of prevention with the many local and systemic treatments for patients at risk of MACCE."