Near-infrared spectroscopy (NIRS) intravascular ultrasound can be used to image mildly obstructive or nonobstructive coronary arteries with the aim of identifying both nonculprit arteries and patients at high risk for future cardiovascular events and should be considered for patients undergoing cardiac catheterization with possible percutaneous coronary intervention (PCI), according to study results published in The Lancet. Studies of NIRS-guided therapy are needed to address and mitigate the high risk for major adverse cardiovascular events (MACE) in these patients and arteries.

NIRS intravascular ultrasound imaging can detect lipid-rich plaques (LRPs), which are associated with acute coronary syndromes or myocardial infarction. This prospective, cohort study (ClinicalTrials.gov NCT02033694) was designed to identify the relationship between LRPs detected at unstented sites by NIRS intravascular ultrasound imaging and any subsequent coronary events from new culprit lesions.

Participants with known or suspected coronary artery disease who underwent cardiac catheterization with possible ad hoc PCI were enrolled from 44 medical centers in Italy, Latvia, the Netherlands, Slovakia, the United Kingdom, and the United States (N=1563) between February 21, 2014 and March 30, 2016. These participants underwent NIRS intravascular ultrasound imaging to scan nonculprit segments. The researchers tested 2 primary hypotheses: (1) at the patient level, the association between the maximum 4-mm Lipid Core Burden Index (maxLCBI4mm) (as a continuous value in 100 units) in all imaged arteries and nonculprit MACE (NC-MACE) during 24-month follow-up; and (2) at the plaque level, if the findings were significant at the 5% level, then the association would be tested between maxLCBI4mm in a segment and occurrence of NC-MACE in that segment during 24-month follow-up.

NIRS intravascular ultrasound device-related events were seen in 6 (0.4%) of 1563 participants. Of the total, 1271 participants (median age, 64 [interquartile range, 57-71] years; 883 [69%] men) with analyzable maxLCBI4mm were allocated to follow-up. PCI was performed in 87% (n=1111) of 1270 participants. The 2-year cumulative incidence of NC-MACE (n=103) was 9%. On a patient level, the unadjusted hazard ratio (HR) for NC-MACE was 1.21 (95% CI, 1.09-1.35; P =.0004) for each 100-unit increase maxLCBI4mm and adjusted HR was 1.18 (95% CI, 1.05-1.32; P =.0043). In participants with a maxLCBI4mm >400, the unadjusted HR for NC-MACE was 2.18 (95% CI, 1.48-3.22; P <.0001) and the adjusted HR was 1.89 (95% CI, 1.26-2.83; P =.0021) to have NC-MACE relative to patients with maxLCBI4mm ≤400. At the plaque level, the unadjusted HR for having a subsequent event in a coronary segment within 24 months was 1.45 (95% CI, 1.3-1.6; P <.0001) for each 100-unit increase in maxLCBI4mm, and for segments with a maxLCBI4mm >400, the unadjusted HR for NC-MACE was 4.22 (95% CI, 2.39-7.45; P <.0001) and aHR was 3.39 (95% CI, 1.85-6.2; P <.0001).

The study investigators concluded, “Nonculprit events continue to occur, and early detection of these events with intravascular imaging remains a challenge. The use of intravascular ultrasound-NIRS has shown its ability to detect NC-MACE in patients undergoing cardiac catheterisation and possible PCI and should be considered as a tool to guide patients and lesions at risk for unanticipated subsequent MACE.”

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They also stated, “We believe that the results of the LRP study should prompt outcome trials incorporating NIRS-guided systemic drug or biologics therapy or localised stent placement to effect outcomes or to change the NIRS imaging finding from baseline.”

Disclosure: This study was supported by Infraredx, Inc. Please see the original reference for a full list of authors’ disclosures.

Reference

Waksman R, Di Mario C, Torguson R, et al. Identification of patients and plaques vulnerable to future coronary events with near-infrared spectroscopy intravascular ultrasound imaging: a prospective, cohort study. Lancet. 2019;394(10209):1629-1637.