Prognostic value in NIRS? There's a glimmer

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Near-infrared spectroscopy (NIRS) may help cardiologists identify at-risk patients with coronary artery disease—one day, that is. In a single-center study, NIRS showed potential as a tool with prognostic value.

Rohit M. Oemrawsingh, MD, MSc, of Erasmus Medical Center in Rotterdam, the Netherlands, and other researchers reported their findings from the ATHEROREMO-IVUS (The European Collaborative Project on Inflammation and Vascular Wall Remodeling in Atherosclerosis–Intravascular Ultrasound) study in the Dec. 16 issue of the Journal of the American College of Cardiology. The substudy enrolled patients for evaluation by NIRS when the technology became commercially available and was added to the center’s catheterization lab.

Their goal was to evaluate the prognostic value of coronary plaque detected by NIRS in patients with stable angina or acute coronary syndrome who were to undergo coronary angiography or PCI. The primary endpoint was major adverse cardiac or cerebrovascular adverse events (MACCE), defined as the composite of all-cause death, nonfatal acute coronary syndrome, stroke or unplanned coronary revascularization at one year.

They enrolled 203 patients between 2009 and 2011 and performed NIRS on a nonculprit coronary artery for the study. The NIRS image data was used to calculate lipid core burden index (LCBI) values.

The LCBI values had a median of 43. The one-year cumulative MACCE rate was 10.4 percent, with unplanned coronary revascularization the most frequent event. For patients with an LCBI at or above the median of 43, the rate of the primary endpoint was 16.7 percent. In those with an LCBI below 43, it was 4 percent.

Oemrawsingh et al found that high LCBI values were associated with a fourfold increase in MAACE at one year.

“Based on diffuse reflectance spectroscopy, NIRS provides a positive and specific chemical measure of cholesterol within the coronary vessel wall, as cholesterol has prominent molecular features in the near-infrared region that can be distinguished from other tissue constituents such as collagen,” they wrote. They proposed that NIRS may outperform intravascular ultrasonography and optical coherence tomography for spotting features in necrotic cores, too, but added that the information in NIRS is two dimensional and can’t show the depth of cholesterol accumulation on the artery wall.

As a small, single-center study, the results are hypothesis-generating only, they wrote. They called for larger studies to confirm their findings.