The Effect of Stent Artefact on Quantification of Plaque Features Using Optical Coherence Tomography (OCT): A Feasibility and Clinical Utility Study

Coronary 18F-sodium fluoride PET detects high-risk plaque features on optical coherence tomography and CT-angiography in patients with acute coronary syndrome

BACKGROUND AND AIMS

¹⁸F-Sodium Fluoride Positron Emission Tomography (¹⁸F-NaF PET) non-invasively detects micro-calcification activity, the earliest stage of atherosclerotic arterial calcification. We studied the association between coronary ¹⁸F-NaF uptake and high-risk plaque features on intra-coronary optical coherence tomography (OCT) and CT-angiography (CTCA) and the potential application to patient-level risk stratification.

METHODS

Sixty-two prospectively recruited patients with acute coronary syndrome (ACS) underwent multi-vessel OCT, ¹⁸F-NaF PET and CTCA. The maximum tissue to background ratio (TBRmax = standardised uptake value (SUV)max/SUVbloodpool) was measured in each coronary segment on ¹⁸F-NaF PET scans. High-risk plaque features on OCT and CTCA were compared in matched coronary segments. The number of patients testing positive (>2SD above the normal range) for micro-calcification activity was determined.

RESULTS

In 62 patients (age, mean ± standard deviation (SD) = 61 ± 9 years, 85% male) the coronary segments with elevated ¹⁸F-NaF uptake had higher lipid arc (LA) (median [25th-75th centile]: 74° [35°-117°] versus 48° [15°-83°], p=0.021), higher prevalence of macrophages [n(%): 37 (62%) versus 89 (39%), p=0.008] and lower plaque free wall (PFW) (50° [7°-110°] versus 94° [34°-180°], p=0.027) on OCT, and a higher total plaque burden (p=0.011) and higher dense calcified plaque burden (p= 0.001) on CTCA, when compared with ¹⁸F-NaF negative segments. Patients grouped by increasing number of coronary lesions positive for microcalcification activity (0,1, ≥2) showed decreasing plaque free wall, increasing calcification and increasing macrophages on OCT (respectively p=0.008, p < 0.001 and p=0.028).

CONCLUSIONS

¹⁸F-NaF uptake is associated with high-risk plaque features on OCT and CTCA in a per-segment and per-patient analysis in subjects hospitalized for ACS.

Mechanism of Drug-Eluting Absorbable Metal Scaffold Restenosis

Background:

The pathomechanisms underlying restenosis of the bioabsorbable sirolimus-eluting metallic scaffold (Magmaris) remain unknown. Using serial optical coherence tomography, we investigated causes of restenosis, including the contribution of late scaffold recoil versus neointimal hyperplasia.

Methods:

Patients enrolled in BIOSOLVE-II undergoing serial angiography and optical coherence tomography (post-intervention and follow-up: 6 months and/or 1 year) were analyzed. Patients were divided into 2 groups according to angiographic in-scaffold late lumen loss (LLL) <0.5 or ≥0.5 mm. End points were late absolute scaffold recoil and neointimal hyperplasia area as assessed by optical coherence tomography.

Results:

Serial data were available for analysis from 70 patients (LLL <0.5 mm: n=41; LLL ≥0.5 mm: n=29). Patient and lesion characteristics were comparable, and there was no significant difference in mean and minimal scaffold area between groups at post-intervention. Late absolute scaffold recoil was less among patients with LLL <0.5 mm (0.53±0.68 mm 2 ) compared with those with LLL ≥0.5 mm (1.48±1.20 mm 2 ; P <0.001). Neointimal hyperplasia area was smaller among patients with LLL <0.5 mm at follow-up (1.47±0.33 mm 2 ) compared with patients with LLL ≥0.5 mm (1.68±0.34 mm 2 ; P =0.013). In a matched-frame analysis (post-intervention and follow-up), late absolute scaffold recoil varied according to the underlying plaque type (lipid: 0.63±1.23 mm 2 ; calcified: 0.81±1.44 mm 2 ; and fibrous: 1.20±1.52 mm 2 ; P <0.001), while there was no difference with regards to neointimal hyperplasia area ( P =0.132).

Conclusions:

In addition to neointimal hyperplasia, late scaffold recoil contributed significantly to LLL of sirolimus-eluting absorbable metal scaffolds. The extent of late scaffold recoil was dependent on the underlying plaque morphology and was the highest among fibrotic lesions.

Registration:

URL: https://www.clinicaltrials.gov . Unique identifier: NCT01960504.