Objective: The histological characteristics of plaque may affect the hemodynamic outcome of a given coronary stenosis. In particular, the potential effect of volumetric calcium content and the topographical distribution in the lesion segment on physiological outcome has not yet been investigated. The aim of this study was to identify any potential correlation between patterns of calcification and the fractional flow reserve (FFR) and the coronary remodeling index (RMI).
Methods: A total of 26 stable angina pectoris and 34 acute coronary syndrome patients without persistent ST-segment elevation constituted the study population. FFR was used to assess 70 intermediate coronary stenosis lesions. After obtaining hemodynamic measurements, quantitative grayscale and virtual histology-intravascular ultrasound analyses were performed. The depth, length, and circumferential distribution of calcification of the lesions were also recorded.
Results: Within the analyzed segment (area of interest, lesion segment), FFR was correlated with maximal thickness of deep calcification (r=-0.285; p=0.021) and calcification angle (r=-0.396; p=0.001). In lesions with a calcification angle >180°, the mean FFR value was significantly lower compared with those <180° (0.64±0.17 vs. 0.78±0.08; p=0.024). RMI was correlated with maximal angle of superficial (r=-0.437; p<0.001) and deep (r=0.425; p<0.001) calcification. RMI was correlated with maximal thickness of superficial (r=-0.357; p=0.003) and deep (r=0.417; p<0.001) calcification. RMI was also correlated with FFR (r=-0.477; p<0.001).
Conclusion: This study demonstrated that the geometry, location, and amount of calcification of a plaque could affect hemodynamic and anatomical outcome measures in functionally significant stenoses by affecting vessel wall compliance.