Background: Intravascular ultrasound radiofrequency analysis (IVUS-RF) characterizes plaque components as necrotic core (NC) and dense calcium (DC). The aim of this study was to perform an IVUS-RF derived analysis of the lesion segment profile in acute coronary syndrome (ACS) patients. Therefore, we compared the site of the minimum lumen area--cross sectional area (mla-CSA) with the worst lesion site--CSA (ws-CSA) defined by the maximum NC site.
Methods: We performed IVUS-RF derived plaque composition and plaque-type classification analysis in 48 ACS patients with 48 culprit (CL) and 69 non-culprit lesions (NCL).
Results: The plaque dimension of the mla- and ws-CSA was significantly different regarding the lumen area (5.18 +/- 2.09 mm2 vs. 6.72 +/- 2.73 mm2, p = 0.0013) and the vessel area (14.80 +/- 5.86 mm2 vs. 17.15 +/- 4.94 mm2, p = 0.0142). The absolute plaque composition was also significantly different regarding the DC tissue (0.71 +/- 0.57 mm2 vs. 0.98 +/- 0.54 mm2, p = 0.0102) and the NC tissue (1.41 +/- 1.28 mm2 vs. 1.85 +/- 1.37 mm2, p = 0.0469). The plaque-type classification revealed significantly more thin cap fibroatheroma (TCFA) lesions at the ws-CSA compared to the mla-CSA (n = 53/89.8% vs. n = 26/44.1%, p < 0.0001). In the majority of the CL and NCL lesion segments the ws-CSA was located proximal to the mla-CSA compared to the distal location (n = 65/55.6% vs. n = 23/19.7%).
Conclusions: In the majority of the lesion segments in ACS patients the ws-CSA is not identical with the mla-CSA. The ws-CSA compared to mla-CSA presented with significantly more NC and DC tissue resulting in a higher amount of TCFA lesions.