Abstract 1983: Pre-intervention Plaque Characteristics by Virtual Histology Intravascular Ultrasound Predict Microvessel Injury Following Percutaneous Coronary Intervention
Background: A novel index of microcirculatory resistance (IMR) has been developed as a reproducible and less hemodynamic dependent index compared with coronary flow reserve (CFR). Although, pre-intervention plaque type assessed by Virtual Histology intravascular ultrasound (VH-IVUS™) has been shown to predict distal embolization during perctaneous coronary intervention (PCI), its impact on IMR is unknown.
Purpose: The purpose of this study was to investigate the relationship between changes in IMR (delta IMR) and coronary plaque component with VH-IVUS.
Methods: Sixteen patients (16 lesions) with angina pectoris underwent VH-IVUS imaging before PCI. Plaque components were classified into 4 elements (fibrous, fibrofatty, dense-calcium and necrotic core). Using a pressure-temperature sensor-tipped coronary wire (Pressure Wire™), CFR and IMR were measured before and after PCI. IMR was calculated as distal coronary pressure (Pd) divided by the inverse of the hyperemic mean transit time. According to delta IMR, patients were divided into two groups group A (delta IMR > 0) and group B (delta IMR ≤ 0). We compared histological composition between the 2 groups.
Results: CFR was improved after PCI in both groups (group A; 1.7±0.6→1.8±0.8, group B; 1.3±0.6→1.8±0.6). By VH-IVUS, although fibrous, fibrofatty and dence-calcium were similarly detected in both groups, percent necrotic core area [=(necrotic core area/total plaque area)×100] was significantly higher in group A than in group B (Figure⇓).
Conclusion: Necrotic core assessed by VH-IVUS was related to the increased IMR during PCI, which may suggest the presence of microvessel injury as a result of micro embolization.