Non-invasive endothelial function assessment using digital reactive hyperaemia correlates with three-dimensional intravascular ultrasound and virtual histology-derived plaque volume and plaque phenotype.

BACKGROUND AND AIM: To study relationships between endothelial dysfunction (ED) and coronary atherosclerosis derived from intravascular ultrasound (IVUS) and virtual histology (VH).
METHODS: Endothelial dysfunction was examined by EndoPAT system (Itamar Medical) in 56 patients who underwent IVUS and VH (Volcano corp.). Reactive hyperaemia index (RHI) < 2 was used for definition of ED. IVUS sequences were divided into 5 mm-long non-overlapping and adjacent vessel segments. Plaque phenotype was determined for each frame and 5 mm vessel segment was labeled according to highest frame score (from 0 for "no lesion" to 5 for "thin cap fibroatheroma; TCFA").
RESULTS: IVUS-VH data were collected from 41 patients suitable for three-dimensional analysis. Patients with ED exhibited larger plaque burden than those without ED (0.46 ± 0.08 vs. 0.39 ± 0.07, p = 0.014), smaller lumen area (8.59 ± 2.19 vs. 11.90 ± 3.50, p = 0.016), higher plaque risk score (2.82 ± 1.18 vs. 1.84 ± 0.90, p = 0.012), and higher number of TCFA frames (0.36 ± 0.22 vs. 0.22 ± 0.16, p = 0.038). Relative amounts of fibrous tissue correlated positively with RHI (p = 0.034, r = 0.33). The numbers of fibroatheromas and calcified plaques correlated with RHI inversely (r = -0.34, p = 0.031 and r = -0.32, p = 0.044, respectively).
CONCLUSIONS: Endothelial dysfunction correlates with severity and phenotype of coronary lesions and can contribute to non-invasive detection of individuals with higher risk of cardiovascular events.