Assessment of radial artery atherosclerosis in acute coronary syndrome patients: an in vivo study using optical coherence tomography

Abstract

Background: Radial artery (RA) atherosclerosis in acute coronary syndrome (ACS) patients has not been systematically observed in vivo. The study aims to characterize plaque morphology and intimal hyperplasia of the RA in patients with ACS, using optical coherence tomography (OCT).

Methods: In this retrospective study involving 239 ACS patients underwent RA OCT without guidewire shadow, 3 groups were divided according to the following criteria: radial artery plaque (RAP) group included patients with fibrous, lipid or calcified plaque; patients without RAP were further classified into radial intimal hyperplasia (RIH) group (intima media thickness ratio [IMR] ≥ 1) or normal group (IMR < 1). The presence and characteristics of RAP and its related risk factors were identified.

Results: The RAP, RIH and normal groups included 76 (31.8%), 69 (28.9%) and 94 (39.3%) patients, respectively. Patients in RAP group were the oldest, compared with those in the RIH and normal groups (p < 0.001), and more frequently had triple vessel disease (p = 0.004). The percentage of plaque rupture (72.4% vs. 56.4%, p = 0.018) and calcification (42.1% vs. 27.6%, p = 0.026) at culprit lesion were significantly higher in patients with RAP than those without RAP. A total of 148 RAP were revealed by OCT, including fibrous (72, 48.6%), lipid (50, 33.8%) and calcified plaques (26, 17.6%). The microvessels were also frequently observed in the RAP group than that in RIH and normal groups (59.2% vs. 8.7% vs. 9.6%, p < 0.001). Multivariate logistic regression analysis showed that age, diabetes, and smoking history (all p < 0.05) were independent risk factors for RAP.

Conclusions: In terms of insights gained from OCT, RA atherosclerosis is not uncommon in ACS patients by OCT, sharing several morphological characters with early coronary atherosclerosis. Aging, diabetes, and smoking are risk factors for RAP.

Keywords: Atherosclerosis; Optical coherence tomography; Peripheral artery disease; Radial artery.

Fig. 1

Representative optical coherence tomography images. A Normal RA with visible three-layer structure. B Concentric intimal hyperplasia in RA: the intima was of uniform thickness, being thinner or only as thick as than the media. C RA with eccentric intimal hyperplasia at 7 to 9 o’ clock positions. D microvessels (arrowheads). E Fibrous plaque (arrowhead) without lipid or calcium component. A signal-rich, homogeneous region is typical for fibrous tissue. F Lipid pool (dotted line) covered by thick fibrous cap. G–H Calcified plaque (asterisk). I Calcified protrusion (arrowhead). RA, radial artery

Fig. 2

Intimal hyperplasia and atherosclerosis of RA and its clinical correlation. A Scatterplots showing a significant positive correlation between the intima media ratio of non-RAP regions and age, indicated by a filled square for each patient in normal (blue), RIH (purple) or RAP (red) groups. B The Number of diseased coronary arteries is compared with RA groups. C The RA atherosclerotic lesion characters in patients with and without TVD. RA, radial artery; RAP, radial artery plaque; RIH, radial artery intimal hyperplasia; TVD, triple vessel disease

Fig. 3

OCT characteristics of coronary artery culprit lesion in patients with or without RAP. Values are n (%). OCT, optical coherence tomography; RAP radial artery plaque; TCFA, thin cap fibroatheroma