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In Vivo Validation of a Catheter-Based Near-Infrared Spectroscopy System for Detection of Lipid Core Coronary Plaques

Initial Results of the SPECTACL Study

Sergio Waxman, MD^_*,_*, Simon R. Dixon, MD, Philippe L'Allier, MD, Jeffrey W. Moses, MD, John L. Petersen, MD^||, Donald Cutlip, MD^¶, Jean-Claude Tardif, MD, Richard W. Nesto, MD^_*, James E. Muller, MD^#, Michael J. Hendricks, BS^#, Stephen T. Sum, PhD^#, Craig M. Gardner, PhD^#, James A. Goldstein, MD, Gregg W. Stone, MD, Mitchell W. Krucoff, MD^||

^_* Lahey Clinic, Burlington, Massachusetts
William Beaumont Hospital, Royal Oak, Michigan
Montreal Heart Institute, Montreal, Canada
Columbia Medical Center, New York, New York
^|| Duke VA Hospital, Durham, North Carolina
^¶ Beth-Israel Medical Center, Boston, Massachusetts
^# InfraReDx, Inc., Burlington, Massachusetts

^_* Reprint requests and correspondence: Dr. Sergio Waxman, Lahey Clinic, 41 Mall Road, Burlington, Massachusetts 01805 (Email: Sergio.Waxman{at}lahey.org).

Objectives: To determine whether catheter-based near-infrared spectroscopy (NIRS) signals obtained with a novel catheter-based system from coronaries of patients are similar to those from autopsy specimens and to assess initial safety of NIRS device.

Background: An intravascular NIRS system for detection of lipid core-containing plaques (LCP) has been validated in human coronary autopsy specimens. The SPECTACL (SPECTroscopic Assessment of Coronary Lipid) trial was a parallel first-in-human multicenter study designed to demonstrate the applicability of the LCP detection algorithm in living patients.

Methods: Intracoronary NIRS was performed in patients undergoing percutaneous coronary intervention. Acquired spectra were blindly compared with autopsy NIRS signals with multivariate statistics. To meet the end point of spectral similarity, at least two-thirds of the scans were required to have >80% of spectra similar to the autopsy spectra.

Results: A total of 106 patients were enrolled; there were no serious adverse events attributed to NIRS. Spectroscopic data could not be obtained in 17 (16%) patients due to technical limitations, leaving 89 patients for analysis. Spectra from 30 patients were unblinded to test the calibration of the LCP detection algorithm. Of the remaining 59 blinded cases, after excluding 11 due to inadequate data, spectral similarity was demonstrated in 40 of 48 spectrally adequate scans (83% success rate, 95% confidence interval: 70% to 93%, median spectral similarity/pullback: 96%, interquartile range 10%). The LCP was detected in 58% of 60 spectrally similar scans from both cohorts.

Conclusions: This intravascular NIRS system safely obtained spectral data in patients that were similar to those from autopsy specimens. These results demonstrate the feasibility of invasive detection of coronary LCP with this novel system. (SPECTACL: SPECTroscopic Assessment of Coronary Lipid; NCT00330928)

Key Words: coronary disease • imaging • spectroscopy

Abbreviations and Acronyms   ACS = acute coronary syndromes   CI = confidence interval   CK = creatine kinase   IVUS = intravascular ultrasound   LCP = lipid core-containing coronary plaques   MD = Mahalanobis distance   MI = myocardial infarction   MLD = minimum lumen diameter   NIRS = near-infrared spectroscopy   PBR = pullback and rotation   PCI = percutaneous coronary intervention   QCA = quantitative coronary angiography   SFR = spectral F-ratio