Near-Infrared Spectroscopy Predicts Cardiovascular Outcome in Patients With Coronary Artery Disease | Journal Scan
Does intracoronary near-infrared spectroscopy (NIRS), a technique which can identify lipid core-containing plaques, have long-term prognostic value in patients with coronary artery disease?
The ATHEROREMO-NIRS (The European Collaborative Project on Inflammation and Vascular Wall Remodeling in Atherosclerosis–Near-Infrared Spectroscopy) substudy 2, a prospective, observational cohort study of 203 patients referred for coronary angiography for stable angina or acute coronary syndrome (ACS), was performed using NIRS imaging in a nonculprit coronary artery. Patients were followed for a primary composite endpoint of all-cause mortality, nonfatal ACS, stroke, and unplanned coronary revascularization. Definite culprit lesion-related events were excluded from the primary analysis. The burden of lipid core-containing plaques was quantified as a lipid core burden index (LCBI) by an independent core lab. Regression and propensity score methods were used to reduce the impact of confounding by risk factors that also affected lipid core/plaque burden.
The authors found that at 1 year, excluding 21 (10.4%) subjects experienced the composite primary endpoint. After adjustment, LCBI above the median (43.0) was associated with 4.0-fold increased risk of the primary endpoint compared to below the median. Although LCBI was all-cause mortality (1.0% vs. 6.9% for below/above median, p = 0.032), this effect was nonsignificant after adjustment (hazard ratio, 6.2; p = 0.10). LCBI was also associated with markedly increased risk of mortality or nonfatal ACS (hazard ratio, 8.9; p = 0.04).
The authors concluded that LCBI above the median was associated with a quadrupling of adverse cardiovascular events during 1-year follow-up.
NIRS is a powerful, invasive technique that can distinguish cholesterol within the coronary wall from collagen and other plaque components based on a distinct molecular signature of cholesterol in the near infrared region. This study demonstrated that lipid-rich plaque burden quantified in this manner is predictive of adverse cardiovascular events. This result has intriguing clinical implications when combined with recent results from the YELLOW (Reduction in Yellow Plaque by Aggressive Lipid-Lowering Therapy) study, which demonstrated that after 6-8 weeks, high-dose statin therapy compared with standard of care statin therapy resulted in reduction of LCBI at the site of untreated obstructive coronary lesions. Additional studies are underway, investigating whether high-dose statin therapies can reduce LCBI in nonculprit lesions. However, with recent US guidelines advocating high-intensity statin therapy in nearly all patients with established coronary artery disease, there may be a role for this technique in selection of patients for additional emerging therapies beyond statins such as PCSK9 antagonists.
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