Association between Tissue Characteristics of Coronary Plaque and Distal Embolization after Coronary Intervention in Acute Coronary Syndrome Patients: Insights from a Meta-Analysis of Virtual Histology-Intravascular Ultrasound Studies

BACKGROUND AND OBJECTIVES: The predictive value of plaque characteristics assessed by virtual histology-intravascular ultrasound (VH-IVUS) including fibrous tissue (FT), fibrofatty (FF), necrotic core (NC) and dense calcium (DC) in identifying distal embolization after percutaneous coronary intervention (PCI) is still controversial. We performed a systematic review and meta-analysis to summarize the association of pre-PCI plaque composition and post-PCI distal embolization in acute coronary syndrome patients. METHODS: Studies were identified in PubMed, OVID, EMBASE, the Cochrane Library, the Current Controlled Trials Register, reviews, and reference lists of relevant articles. A meta-analysis using both fixed and random effects models with assessment of study heterogeneity and publication bias was performed. RESULTS: Of the 388 articles screened, 10 studies with a total of 872 subjects (199 with distal embolization and 673 with normal flow) met the eligibility of our study. Compared with normal flow groups, significant higher absolute volume of NC [weighted mean differences (WMD): 5.79 mm(3), 95% CI: 3.02 to 8.55 mm(3); p<0.001] and DC (WMD: 2.55 mm(3), 95% CI: 0.22 to 4.88 mm(3); p = 0.03) were found in acute coronary syndrome patients with distal embolization. Further subgroup analysis demonstrated that the predictive value of tissue characteristics in determining distal embolization was correlated to clinical scenario of the patients, definition of distal embolization, and whether the percutaneous aspiration thrombectomy was applied. CONCLUSION: Our study that pooled current evidence showed that plaque components were closely related to the distal embolization after PCI, especially the absolute volume of NC and DC, supporting further studies with larger sample size and high-methodological quality.