Catheter-based Near-infrared Spectroscopy Research Articles

Robust, high-density lesion mapping in the left atrium with near-infrared spectroscopy.

Radiofrequency ablation (RFA) procedures for atrial fibrillation frequently fail to prevent recurrence, partially due to limitations in assessing extent of ablation. Optical spectroscopy shows promise in assessing RFA lesion formation but has not been validated in conditions resembling those in vivo. Catheter-based near-infrared spectroscopy (NIRS) was applied to porcine hearts to demonstrate that spectrally derived optical indices remain accurate in blood and at oblique incidence angles. Porcine left atria were ablated and mapped using a custom-fabricated NIRS catheter. Each atrium was mapped first in phosphate-buffered saline (PBS) then in porcine blood. NIRS measurements showed little angle dependence up to 60deg. A trained random forest model predicted lesions with a sensitivity of 81.7%, a specificity of 86.1%, and a receiver operating characteristic curve area of 0.921. Predicted lesion maps achieved a mean structural similarity index of 0.749 and a mean normalized inner product of 0.867 when comparing maps obtained in PBS and blood. Catheter-based NIRS can precisely detect RFA lesions on left atria submerged in blood. Optical parameters are reliable in blood and without perpendicular contact, confirming their ability to provide useful feedback during in vivo RFA procedures.

Human Basilar Arterial Plaque Detected by Near-Infrared Spectroscopy: Clinical Image

A patient in their 70s presented with weakness of the left limb and aphasia. Left vertebral angiography showed acute basilar artery occlusion. After mechanical thrombectomy, basilar artery trunk stenosis was evident and catheter-based near-infrared spectroscopy (NIRS) showed lipid-rich atherosclerotic plaque extending to almost 220° of the vessel circumference in the culprit lesion. Loading doses of dual antiplatelet therapy and aggressive medical treatment were started because additional intervention might have increased risk of plaque protrusion and thrombotic reocclusion. The patient presented with minor stroke caused by restenosis of the basilar artery 4 months later; balloon angioplasty and stenting were performed without thromboembolic complications. The patient was discharged without any new neurologic deficits. NIRS visualizes the distribution of lipids in the culprit lesion and the plaque burden of residual stenosis, identifies mechanisms of in situ thrombosis, and provides suggestions for the timing of additional interventions.

Dual-layered stents reduce cerebral embolism compared with first-generation stents during carotid stenting of high lipid core plaque lesions

BackgroundPeriprocedural lipid core plaque (LCP) has been detected in carotid arteries assessed by catheter-based near-infrared spectroscopy (NIRS). High LCP is associated with cerebral embolism after carotid artery stenting (CAS) using...

Near-infrared spectroscopy carotid plaque characteristics and cerebral embolism in carotid artery stenting.

Perioperative thromboembolism is the main consideration in carotid artery stenting (CAS). Precise evaluation of carotid plaque components is clinically important to reduce ischaemic complications since CAS mechanically pushes plaque outwards, which releases plaque debris into the bloodstream. This study aimed to determine whether high lipid core plaque (LCP) assessed by catheter-based near-infrared spectroscopy (NIRS) is associated with ipsilateral cerebral embolism by diffusion-weighted magnetic resonance imaging during CAS using a first-generation stent. Carotid stenosis magnetic resonance (MR) T1-weighted plaque signal intensity ratio (T1W-SIR) followed by NIRS assessment at the time of CAS (using the carotid artery Wallstent) was performed in 117 consecutive patients. The maximum lipid core burden index (max-LCBI) at minimal luminal areas (MLA; max-LCBIMLA) and the max-LCBI for any 4 mm segment in a target lesion defined as max-LCBIarea were significantly higher for the post-procedural new ipsilateral diffusion-weighted magnetic resonance imaging (DWI)-positive than negative patients (p<0.001 for all). There was a significant linear correlation between max-LCBIarea and the number of new emboli (r=0.544, p<0.0001). We also found that the second quantile (Q2) of T1W-SIRMLA had a significantly higher max-LCBIMLA and a higher incidence of DWI positivity than Q1 and Q3 (p<0.001 for all). Furthermore, max-LCBIMLA appeared to distinguish between patients with and without postoperative new ipsilateral DWI positivity (AUC 0.91, 95% CI: 0.86-0.96; p<0.0001). High LCP assessed by NIRS is associated with cerebral embolism by diffusion-weighted imaging in CAS using a first-generation stent.

Lipid Core Burden Index Assessed by Near-Infrared Spectroscopy of Symptomatic Carotid Plaques: Association with Magnetic Resonance T1-Weighted Imaging

Introduction: Vulnerable plaques are a strong predictor of cerebrovascular ischemic events, and high lipid core plaques (LCPs) are associated with an increased risk of embolic infarcts during carotid artery stenting (CAS). Recent developments in magnetic resonance (MR) plaque imaging have enabled noninvasive assessment of carotid plaque vulnerability, and the lipid component and intraplaque hemorrhage (IPH) are visible as high signal intensity areas on T1-weighted MR images. Recently, catheter-based near-infrared spectroscopy (NIRS) has been shown to accurately distinguish LCPs without IPH. This study aimed to determine whether the results of assessment of high LCPs by catheter-based NIRS correlate with the results of MR plaque imaging. Methods: We recruited 82 consecutive symptomatic carotid artery stenosis patients who were treated with CAS under NIRS and MR plaque assessment. Maximum lipid core burden index (max-LCBI) at minimal luminal areas (MLA), defined as max-LCBI_MLA, and max-LCBI for any 4-mm segment in a target lesion, defined as max-LCBI_AREA, were assessed by NIRS. Correlations were investigated between max-LCBI and MR T1-weighted plaque signal intensity ratio (T1W-SIR) and MR time-of-flight signal intensity ratio (TOF-SIR) in the same regions as assessed by NIRS. Results: Both T1W-SIR_MLA and T1W-SIR_AREA were significantly lower in the high LCP group (max-LCBI >504, p < 0.001 for both), while TOF-SIR_MLA and TOF-SIR_AREA were significantly higher in the high LCP group (p < 0.001 and p = 0.004, respectively). A significant linear correlation was present between max-LCBI_MLA and both TIW-SIR_MLA and TOF-SIR_MLA (r = −0.610 and 0.452, respectively, p < 0.0001 for both). Furthermore, logistic regression analysis revealed that T1W-SIR_MLA and TOF-SIR_MLA were significantly associated with a high LCP assessed by NIRS (OR, 44.19 and 0.43; 95% CI: 6.55–298.19 and 0.19–0.96; p < 0.001 and = 0.039, respectively). Conclusions: A high LCP assessed by NIRS correlates with the signal intensity ratio of MR imaging in symptomatic patients with unstable carotid plaques.

TCT-291 Detection of Thin and Thick Fibrous Caps Overlying Lipid Core Coronary Plaques with a Catheter-Based Near-Infrared Spectroscopy System

TCT-291 Detection of Thin and Thick Fibrous Caps Overlying Lipid Core Coronary Plaques with a Catheter-Based Near-Infrared Spectroscopy System

Disparity between angiographic coronary lesion complexity and lipid core plaques assessed by near‐infrared spectroscopy

The purpose of this study was to determine if there was a relationship between angiographic lesion complexity and the extent of lipid core plaque (LCP) identified by catheter-based near-infrared spectroscopy (NIRS). The angiographic complexity of coronary artery disease (CAD) is used to predict outcomes in patients undergoing percutaneous coronary intervention (PCI). The SYNTAX score, an angiographic tool quantifying the complexity of CAD, is associated with PCI outcomes. Recently, a novel catheter-based imaging technique using NIRS can identify LCP, which also is associated with PCI periprocedural myocardial infarction (MI). However, it is unknown whether these events are related to distinct adverse event prone pathobiology, such as a LCP within a complex angiographic lesion. Thus, we hypothesized that LCP identified by NIRS would be associated with high SYNTAX score. Seventy-eight patients who underwent coronary angiography and target-vessel NIRS were selected from the Chemometric Observations of Lipid Core Containing Plaques of Interest in Native Coronary Arteries Registry, an industry sponsored registry to collate clinical findings in all patients undergoing NIRS evaluation. A lipid core burden index (LCBI) was obtained from the scan of the proximal 50 mm of the target vessel. Three vessel SYNTAX (total, tSYN) and target single vessel (only NIRS-interrogated vessel) SYNTAX (1vSYN) scores were calculated and compared to LCBI. High LCBI was defined as (>110) and was compared to tertile scores for 1vSYN score (low 0-5, intermediate 6-10, high ≥11) and previously established tertiles for tSYN score (low 0-22, intermediate 23-32, high ≥33). Patients had mean age of 63 years with prevalence of females (10%), diabetes mellitus (28%), hypertension (88%), and smoking history (72%); 1vSYN and tSYN scores correlated poorly with LCBI [(r(2) = 0.25; P = 0.02; n = 78) and (r(2) = 0.24; P = 0.04; n = 78), respectively]. Mean LCBI did not differ significantly across all tertiles of 1vSYN or tSYN scores. Angiographic SYNTAX score only weakly correlated with LCBI. It is of interest as well that high LCBI was also present in cases of low SYNTAX scores. The disparity between the degree of angiographic complexity and the amount of LCP supports postulated mechanisms of the adverse event propensity even in patients who demonstrate low angiographic complexity. Future studies are necessary to address the clinical significance of high LCBI in patients with low-to-intermediate angiographic complexity and their potential for PCI-related complications.

Detection of Lipid-Core Plaques by Intracoronary Near-Infrared Spectroscopy Identifies High Risk of Periprocedural Myocardial Infarction

Percutaneous coronary intervention (PCI) is associated with periprocedural myocardial infarction (MI) in 3% to 15% of cases (depending on the definition used). In many cases, these MIs result from distal embolization of lipid-core plaque (LCP) constituents. Prospective identification of LCP with catheter-based near-infrared spectroscopy (NIRS) may predict an increased risk of periprocedural MI and facilitate development of preventive measures. The present study analyzed the relationship between the presence of a large LCP (detected by NIRS) and periprocedural MI. Patients with stable preprocedural cardiac biomarkers undergoing stenting were identified from the COLOR Registry, an ongoing prospective observational study of patients undergoing NIRS before PCI. The extent of LCP in the treatment zone was calculated as the maximal lipid-core burden index (LCBI) measured by NIRS for each of the 4-mm longitudinal segments in the treatment zone. A periprocedural MI was defined as new cardiac biomarker elevation above 3× upper limit of normal. A total of 62 patients undergoing stenting met eligibility criteria. A large LCP (defined as a maxLCBI(4 mm) ≥500) was present in 14 of 62 lesions (22.6%), and periprocedural MI was documented in 9 of 62 (14.5%) of cases. Periprocedural MI occurred in 7 of 14 patients (50%) with a maxLCBI(4 mm) ≥500, compared with 2 of 48 patients (4.2%) patients with a lower maxLCBI(4 mm) (P=0.0002). NIRS provides rapid, automated detection of extensive LCPs that are associated with a high risk of periprocedural MI, presumably due to embolization of plaque contents during coronary intervention.

Catheter-Based Near-Infrared Spectroscopy for Imaging of Lipid-Rich Plaques

Lipid core–containing coronary plaques (LCPs), which cause most acute coronary syndromes and complications related to percutaneous coronary intervention (PCI), cannot be detected with coronary angiography. A near-infrared spectroscopy (NIRS) catheter-based system has been developed for intracoronary detection of LCP. The system was validated ex vivo in an autopsy study and in vivo in the multicenter SPECTACL study. Anecdotal case reports are emerging that hint at the clinical utility of this device in patients with coronary artery disease undergoing PCI in terms of predicting no-reflow, periprocedural myocardial infarction, or determining optimal stent length. However, it is not known whether widespread use of this device will translate into clinical benefit, a question which will need to be investigated in future studies. In this article, we review the evolution of NIRS technology in detection of LCP and the future direction of this imaging modality in optimizing the results of PCI.

Near-infrared spectroscopy for the detection of lipid core coronary plaques

Lipid core coronary plaques (LCPs), which cannot be reliably detected by conventional diagnostic measures, are widely considered to be the cause of most acute coronary syndromes. Accumulating evidence also indicates that LCPs may increase the risk of stenting complications. A catheter-based near-infrared spectroscopy (NIRS) system is now available for the detection of LCPs in the arteries of patients undergoing coronary angiography. The system, which uses the well-documented ability of NIRS to determine the chemical composition of unknown substances, has been validated in an autopsy study and a clinical trial. The system has now been used in more than 300 patients and has provided novel information for use in assessment of coronary disease. Multiple studies are in progress to assess the full clinical benefit of NIRS for the goals of 1) improving the safety of stenting, 2) preventing a second coronary event in patients with known coronary disease, and 3) use as a possible component in a strategy for the primary prevention of coronary events.

In Vivo Validation of a Catheter-Based Near-Infrared Spectroscopy System for Detection of Lipid Core Coronary Plaques: Initial Results of the SPECTACL Study

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. 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. 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. 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. 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).

Detection of Lipid Core Coronary Plaques in Autopsy Specimens With a Novel Catheter-Based Near-Infrared Spectroscopy System

This study sought to assess agreement between an intravascular near-infrared spectroscopy (NIRS) system and histology in coronary autopsy specimens. Lipid core plaques cannot be detected by conventional tests, yet are suspected to be the cause of most acute coronary syndromes. Near-infrared spectroscopy is widely used to determine the chemical content of substances. A NIRS system has been developed and used successfully in 99 patients. Scanning NIRS was performed through blood in 212 coronary segments from 84 autopsy hearts. One histologic section was analyzed for every 2 mm of artery. Lipid core plaque of interest (LCP) was defined as a lipid core >60 degrees in circumferential extent, >200-microm thick, with a mean fibrous cap thickness <450 microm. The first 33 hearts were used to develop the algorithm; the subsequent 51 validation hearts were used in a prospective, double-blind manner to evaluate the accuracy of NIRS in detecting LCP. A NIRS-derived lipid core burden index for an entire artery was also validated by comparison to histologic findings. The LCPs were present in 115 of 2,649 (4.3%) sections from the 51 validation hearts. The algorithm prospectively identified LCP with a receiver-operator characteristic area of 0.80 (95% confidence interval [CI]: 0.76 to 0.85). The lipid core burden index detected the presence or absence of any fibroatheroma with an area under the curve of 0.86 (95% CI: 0.81 to 0.91). A retrospective analysis of lipid core burden index conducted in extreme artery segments with either no or extensive fibroatheroma yielded an area under the curve of 0.96 (95% CI: 0.92 to 1.00), confirming the accuracy of spectroscopy in identifying plaques with markedly different lipid content under ideal circumstances. This novel catheter-based NIRS system accurately identified lipid core plaques through blood in a prospective study in coronary autopsy specimens. It is expected that this novel capability will be of assistance in the management of patients with coronary artery disease.