Coronary lipid-rich plaque characteristics in Japanese patients with acute coronary syndrome and stable angina: A near infrared spectroscopy and intravascular ultrasound study

BACKGROUND: Asians have a much lower incidence of adverse coronary events than Caucasians. We sought to evaluate the characteristics of coronary lipid-rich plaques (LRP) in Asian patients with acute coronary syndrome (ACS) and stable angina (SA). We also aimed to identify surrogate markers for the extent of LRP. METHODS: We evaluated 207 patients (ACS, n = 75; SA, n = 132) who underwent percutaneous coronary intervention under near infrared spectroscopy intravascular ultrasound (NIRS-IVUS). Plaque characteristics and the extent of LRP [defined as a long segment with a 4-mm maximum lipid-core burden index (maxLCBI(4mm))] on NIRS in de-novo culprit and non-culprit segments were analyzed. RESULTS: The ACS culprit lesions had a significantly higher maxLCBI(4mm) (median [interquartile range (IQR)]: 533 [385–745] vs. 361 [174–527], p < 0.001) than the SA culprit lesions. On multivariate logistic analysis, a large LRP (defined as maxLCBI(4mm) ≥ 400) was the strongest independent predictor of the ACS culprit segment (odds ratio, 3.87; 95% confidence interval, 1.95–8.02). In non-culprit segments, 19.8% of patients had at least one large LRP without a small lumen. No significant correlation was found between the extent of LRP and systematic biomarkers (hs-CRP, IL-6, TNF-α), whereas the extent of LRP was positively correlated with IVUS plaque burden (r = 0.24, p < 0.001). CONCLUSIONS: We confirmed that NIRS-IVUS plaque assessment could be useful to differentiate ACS from SA culprit lesions, and that a threshold maxLCBI(4mm) ≥ 400 was clinically suitable in Japanese patients. No surrogate maker for a high-risk LRP was found; consequently, direct intravascular evaluation of plaque characteristics remains important.