Author + information
- Jimmy Su1,
- Cherry Greiner1,
- Stephanie Grainger2,
- Matthew Saybolt3,
- William Pickering4,
- Robert Wilensky3,
- Joel Raichlen5,
- Veronica He6,
- Stephen Sum7,
- James Muller8 and
- Sean Madden2
- 1Infraredx, Burlington, Massachusetts, United States
- 2Infraredx, Inc., Burlington, Massachusetts, United States
- 3Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, United States
- 4Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States
- 5AstraZeneca, Gaithersburg, Maryland, United States
- 6Infraredx Inc, Burlington, Massachusetts, United States
- 7InfraReDx, Burlington, Massachusetts, United States
- 8InfraReDx, Inc., Burlington, Massachusetts, United States
Previous clinical studies have shown that plaque burden (PB) >70%, as measured by intravascular ultrasound (IVUS), is predictive of future coronary events. But because IVUS tracing of PB is time-consuming, results from PROSPECT I did not significantly alter clinical practice. In addition to PB, the lipid content of coronary plaques can now be assessed in patients with a combined near-infrared spectroscopy (NIRS)-IVUS catheter. A NIRS measure of lipid core burden index (LCBI) is provided automatically. Hence, NIRS-IVUS may offer increased ease of use, over IVUS alone. The relationship between IVUS-determined PB and NIRS-measured LCBI was evaluated in human autopsy coronary data.
Autopsy data were acquired from 95 individuals with at least one risk factor for coronary artery disease. Coronary segments (n=387) were imaged using intravascular NIRS/IVUS. Histology slides were prepared every 2mm along each artery. PB was computed by IVUS/histology and LCBI was computed by the NIRS chemogram for each 2mm artery section.
A weak correlation (r=0.42) was found between LCBI and PB (Fig. 1). Fibrotic plaques, that is, those with high PB and low LCBI, likely contributed to this low association. Sections with low PB (<40%) but high LCBI (>250) were noticeably scarce.
NIRS, in an automated manner, can determine if lesions with large PB contain high amounts of lipid. Hence NIRS imaging, which is currently being evaluated in two large outcomes studies for its ability to predict coronary events, has the potential to increase the ease-of-use and specificity of IVUS-derived PB for the prediction of coronary events.