P6184Association of coronary plaque characteristics and the translesional gradient by FFRct in asymptomatic patients with newly diagnosed type-2 diabetes mellitus
Authors: Mrgan M , Norgaard B L , Dey D , Gram J B , Olsen M H , Gram J B , Sand N P R 
Published: October 2019

Abstract

Background
Coronary CT angiography (CCTA) derived fractional flow reserve (FFRct) is increasingly for decision-making in patients with stable chest pain. The relation between vessel specific plaque characteristics and the translesional gradient by FFRct in patients with type-2 diabetes mellitus (T2DM) is not fully explored.

Purpose
To examine the association between vessel specific plaque characteristics as determined by CCTA and the translesional gradient as assessed by FFRct in asymptomatic patients with newly diagnosed T2DM.

Methods
Total plaque volume and the volumes of calcified plaque (CP), low-density noncalcified plaque (LD-NCP) and non-LD-NCP were assessed on a per-vessel basis by quantitative plaque analysis using Autoplaque. Irregularities of the vessel wall giving a vessel-specific total plaque volume <50 mm3 were excluded from the analyses. Positive remodeling was defined by a remodeling index >1.1. Spotty calcification was defined as calcifications comprising <90° of the vessel circumference and <3 mm length. FFRct-analysis was performed from standard acquired CCTA data sets by HeartFlow. Any FFRct-value in the major coronary arteries >1.8 mm in diameter was registered. The translesional gradient, defined as the difference of FFRct-values immediately proximal and distal to lesion, was calculated in most severe lesion per-vessel. Lesions were categorized according to a ΔFFRct threshold of 0.06. Plaque analysis and comparison to ΔFFRct were performed by staff blinded to patient data.

Results
A total of 76 patients; age, mean (SD): 56 (11) years; males, n (%): 49 (65), with newly diagnosed (<1 year) T2DM were studied. Haemoglobin A1c, median (IQR) was 45 mmol/L (42–50). Risk factors, mean (SD) were as follows: total-cholesterol, 4.4 mmol/L (1.0); LDL-cholesterol, 2.5 mmol/L (0.8); systolic blood pressure, 131 mmHg (12). In the analysis 57 vessels in 30 patients were included, while 24 vessels were classified as having irregularities. ΔFFRct ≥0.06 was registered in 22 (39%) plaques. Vessel specific plaque volumes (mm3), ΔFFRct ≥0.06 vs. ΔFFRct <0.06, were, median (IQR): LD-NCP, 28.1 (9.5–62.3) vs. 18.3 (10.2–27.5); non-LD-NCP, 129.5 (74.1–186.8) vs. 98.1 (65.7–142.1); total plaque volume, 209.4 (137.1–359.3) vs. 139.6 (108.3–220.0), all p>0.05. The vessel-specific CP volume, median (IQR), was higher in vessels with ΔFFRct ≥0.06 vs. ΔFFRct <0.06: 51.9 (20.5–85.4) vs. 13.5 (4.1–68.5), p=0.015. Adverse plaque characteristics ΔFFRct ≥0.06 vs. ΔFFRct <0.06, were, n (%): positive remodeling, 21 (95%) vs. 34 (97%) and spotty calcification, 9 (41%) vs. 14 (40%). The relative distribution of vessel specific plaque components according to ΔFFRct is illustrated in the Figure.

Conclusion
In asymptomatic patients with newly diagnosed and well-controlled T2DM, the occurrence of high-risk coronary plaque features was frequently observed. The applied translesional gradient by FFRct was not predictive of adverse coronary plaque characteristics.

Acknowledgement/Funding
The Danish Diabetes Academy supported by the Novo Nordisk Foundation; University of Southern DenmarkCenter Southwest, Denmark