Coronary optical frequency domain imaging (OFDI) for in vivo evaluation of stent healing: comparison with light and electron microscopy.
OBJECTIVE
Coronary late stent thrombosis, a rare but devastating complication, remains an important concern in particular with the increasing use of drug-eluting stents. Notably, pathological studies have indicated that the proportion of uncovered coronary stent struts represents the best morphometric predictor of late stent thrombosis. Intracoronary optical frequency domain imaging (OFDI), a novel second-generation optical coherence tomography (OCT)-derived imaging method, may allow rapid imaging for the detection of coronary stent strut coverage with a markedly higher precision when compared with intravascular ultrasound, due to a microscopic resolution (axial approximately 10-20 microm), and at a substantially increased speed of image acquisition when compared with first-generation time-domain OCT. However, a histological validation of coronary OFDI for the evaluation of stent strut coverage in vivo is urgently needed. Hence, the present study was designed to evaluate the capacity of coronary OFDI by electron (SEM) and light microscopy (LM) analysis to detect and evaluate stent strut coverage in a porcine model.


RESULTS
Twenty stents were implanted into 10 pigs and coronary OFDI was performed after 1, 3, 10, 14, and 28 days. Neointimal thickness as detected by OFDI correlated closely with neointimal thickness as measured by LM (r = 0.90, P < 0.01). The comparison of stent strut coverage as detected by OFDI and SEM analysis revealed an excellent agreement (r = 0.96, P < 0.01). In particular, stents completely covered by OFDI analysis were also completely covered by SEM analysis. All incompletely covered stents by OFDI were also incompletely covered by SEM. Analyses of fibrin-covered stent struts suggested that these may rarely be detected as uncovered stent struts by OFDI. Importantly, optical density measurements revealed a significant difference between fibrin- and neointima-covered coronary stent struts [0.395 (0.35-0.43) vs. 0.53 (0.47-0.57); P < 0.001], suggesting that differences in optical density provide information on the type of stent strut coverage. The sensitivity and specificity for detection of fibrin vs. neointimal coverage was evaluated using receiver-operating characteristic analysis.


CONCLUSIONS
The present study demonstrates that OFDI is a highly promising tool for accurate evaluation of coronary stent strut coverage, as supported by a high agreement between OFDI and light and electron microscopic analysis. Furthermore, our data indicate that optical density measurements can provide additional information with respect to the type of stent strut coverage, i.e. fibrin vs. neointimal coverage. Therefore, coronary OFDI analysis will provide important information on the biocompatibility of coronary stents.
Department of Cardiology, Cardiovascular Center, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland. christian.templin@usz.ch
Christian
C
Templin
Martin
M
Meyer
Maja Franziska
MF
Müller
Valentin
V
Djonov
Ruslan
R
Hlushchuk
Ivanka
I
Dimova
Stefanie
S
Flueckiger
Peter
P
Kronen
Michele
M
Sidler
Karina
K
Klein
Flora
F
Nicholls
Jelena-Rima
JR
Ghadri
Klaus
K
Weber
Dragica
D
Paunovic
Roberto
R
Corti
Simon P
SP
Hoerstrup
Thomas F
TF
Lüscher
Ulf
U
Landmesser
D000818:Animals; D003331:Coronary Vessels / Q000033:anatomy & histology; D005337:Fibrin / Q000032:analysis; D006083:Graft Occlusion, Vascular / Q000209:etiology; D008853:Microscopy; D008855:Microscopy, Electron, Scanning; D011475:Prosthesis Failure / Q000209:etiology; D012372:ROC Curve; D015607:Stents; D013552:Swine; D041623:Tomography, Optical Coherence / Q000379:methods*; D014945:Wound Healing / Q000502:physiology*
D005337:Fibrin