Repeatability Assessment of Intravascular Polarimetry in Patients.

Intravascular polarimetry with polarization sensitive optical frequency domain imaging (PS-OFDI) measures polarization properties of the vessel wall and offers characterization of coronary atherosclerotic lesions beyond the cross-sectional image of arterial microstructure available to conventional OFDI. A previous study of intravascular polarimetry in cadaveric human coronary arteries found that tissue birefringence and depolarization provide valuable insight into key features of atherosclerotic plaques. In addition to various tissue components, catheter and sample motion can also influence the polarization of near infrared light as used by PS-OFDI. This paper aimed to evaluate the robustness and repeatability of imaging tissue birefringence and depolarization in a clinical setting. 30 patients scheduled for percutaneous coronary intervention at the Erasmus Medical Center underwent repeated PS-OFDI pullback imaging, using commercial imaging catheters in combination with a custom-built PS-OFDI console. We identified 274 matching cross sections among the repeat pullbacks to evaluate the reproducibility of the conventional backscatter intensity, the birefringence, and the depolarization signals at each spatial location across the vessel wall. Bland-Altman analysis revealed best agreement for the birefringence measurements, followed by backscatter intensity, and depolarization, when limiting the analysis to areas of meaningful birefringence. Pearson correlation analysis confirmed highest correlation for birefringence (0.86), preceding backscatter intensity (0.83), and depolarization (0.78). Our results demonstrate that intravascular polarimetry generates robust maps of tissue birefringence and depolarization in a clinical setting. This outcome motivates the use of intravascular polarimetry for future clinical studies that investigate polarization properties of arterial atherosclerosis.

Differential thrombotic prolapse burden in either bioresorbable vascular scaffolds or metallic stents implanted during acute myocardial infarction: The snowshoe effect: Insights from the maximal footprint analysis.

BACKGROUND: The hypothesized increased thrombus entrapment during bioresorbable vascular scaffold implantation in acute myocardial infarction, the so-called "snowshoe effect" has never been demonstrated. METHODS: Patients enrolled in the BVS STEMI FIRST study matched with STEMI patients implanted with everolimus-eluting metal stents (EES) and undergoing optical coherence tomography (OCT) at the index procedure were compared. Quantitative coronary angiography analysis and optical coherence tomography data for evaluation of thrombotic prolapse were reported. Percentage maximal footprint (%MFP) analysis as an indicator of the snowshoe effect was performed. RESULTS: A total of 302 patients were analyzed (151 with BVS and 151 with EES). Of those patients 30 implanted with BVS and 17 implanted with EES were imaged at the index procedure with OCT. Baseline clinical characteristics, TIMI-flow and thrombus burden were similar between groups. Aspiration thrombectomy was similarly performed in the two groups (BVS 83.3% vs 94.1% EES, p=0.405). At the end of the procedure, final TIMI 3 flow was achieved in 93.3% and 82.4% of BVS and EES patients respectively (p=0.296). The %MFP was significantly higher in the BVS treated patients (36.59±5.65% vs 17.61±4.30, p<0.001). The results of the OCT analysis showed a mean prolapse area (0.61±0.26mm(2) vs 0.90±0.31mm(2), p=0.001) and a percentage prolapse area (7.11±2.98mm(2) vs 9.98±2.90mm(2), p=0.002) significantly higher in the EES group. CONCLUSIONS: Scaffold structural characteristics such as strut width may play a role in terms of thrombus dislodgment patterns and acute prolapsing material.

Multimodality Intra-Arterial Imaging Assessment of the Vascular Trauma Induced by Balloon-Based and Nonballoon-Based Renal Denervation Systems.

BACKGROUND: Renal denervation is a new treatment considered for several possible indications. As new systems are introduced, the incidence of acute renal artery wall injury with relation to the denervation method is unknown. We investigated the acute repercussion of renal denervation on the renal arteries of patients treated with balloon-based and nonballoon-based denervation systems by quantitative angiography, intravascular ultrasound, and optical coherence tomography (OCT). METHODS AND RESULTS: Twenty-five patients (50 renal arteries) underwent bilateral renal denervation with 5 different systems, 3 of which balloon-based (Paradise [n=5], Oneshot [n=6], and Vessix V2 [n=5)]) and 2 nonballoon-based (Symplicity [n=6] and EnligHTN [n=3]). Analysis included quantitative angiography and morphometric intravascular ultrasound measurements pre and post procedure and assessment of vascular trauma (dissection, edema, or thrombus) by OCT after denervation. A significant reduction in lumen size by quantitative angiography and intravascular ultrasound was observed in nonballoon denervation but not in balloon denervation. By postdenervation OCT, dissection was seen in 14 arteries (32.6%). The percentage of frames with dissection was higher in balloon-based denervation catheters. Thrombus and edema were detected in 35 (81.4%) and 32 (74.4%) arteries, respectively. In arteries treated with balloon-based denervation that had dissection by OCT, the balloon/artery ratio was higher (1.24 [1.17-1.32] versus 1.10 [1.04-1.18]; P<0.01). CONCLUSIONS: A varying extent of vascular injury was observed after renal denervation in all systems; however, different patterns were identified in balloon-based and in nonballoon-based denervation systems. In balloon denervation, the presence of dissections by OCT was associated with a higher balloon/artery ratio.

A novel method to assess coronary artery bifurcations by OCT: cut-plane analysis for side-branch ostial assessment from a main-vessel pullback.

AIMS: In coronary bifurcations assessment, evaluation of side-branch (SB) ostia by an optical coherence tomography (OCT) pullback performed in the main branch (MB) could speed up lesion evaluation and minimize contrast volume. Dedicated software that reconstructs the cross-sections perpendicular to the SB centreline could improve this assessment. We aimed to validate a new method for assessing the SB ostium from an OCT pullback performed in the MB. METHODS AND RESULTS: Thirty-one sets of frequency-domain OCT pullbacks from 28 patients, both from the MB and the SB of a coronary artery bifurcation were analysed. Measurements of the SB ostium from the SB pullback were used as a reference. Measurements of the SB ostium from the MB pullback were then performed in a laboratory setting by (i) conventional analysis and (ii) cut-plane analysis, and the measurement error for each analysis was estimated. Correlations of SB ostium measurements acquired from the MB pullback in comparison with reference measurements acquired from the SB pullback were higher with cut-plane analysis compared with conventional analysis, albeit not reaching statistical significance (area: rcut-plane = 0.927 vs. rconventional = 0.870, P = 0.256; mean diameter: rcut-plane = 0.918 vs. rconventional = 0.788, P = 0.056; minimum diameter: rcut-plane = 0.841 vs. rconventional = 0.812, P = 0.734; maximum diameter: rcut-plane = 0.770 vs. rconventional = 0.635, P = 0.316). Cut-plane analysis was associated with lower absolute error than conventional analysis (area: 0.56 ± 0.45, vs. 1.50 ± 1.31 mm(2), P < 0.001; mean diameter: 0.18 ± 0.14 vs. 0.44 ± 0.30 mm, P < 0.001). CONCLUSION: Measurements of SB ostium performed in a laboratory setting by cut-plane analysis of an OCT pullback of the main branch have high correlation with reference measurements performed in a SB OCT pullback and lower error compared with conventional analysis.

OCT assessment of the long-term vascular healing response 5 years after everolimus-eluting bioresorbable vascular scaffold.

BACKGROUND: Although recent observations suggest a favorable initial healing process of the everolimus-eluting bioresorbable vascular scaffold (BVS), little is known regarding long-term healing response. OBJECTIVES: This study assessed the in vivo vascular healing response using optical coherence tomography (OCT) 5 years after elective first-in-man BVS implantation. METHODS: Of the 14 living patients enrolled in the Thoraxcenter Rotterdam cohort of the ABSORB A study, 8 patients underwent invasive follow-up, including OCT, 5 years after implantation. Advanced OCT image analysis included luminal morphometry, assessment of the adluminal signal-rich layer separating the lumen from other plaque components, visual and quantitative tissue characterization, and assessment of side-branch ostia "jailed" at baseline. RESULTS: In all patients, BVS struts were integrated in the vessel and were not discernible. Both minimum and mean luminal area increased from 2 to 5 years, whereas lumen eccentricity decreased over time. In most patients, plaques were covered by a signal-rich, low-attenuating layer. Minimum cap thickness over necrotic core was 155 ± 90 µm. One patient showed plaque progression and discontinuity of this layer. Side-branch ostia were preserved with tissue bridge thinning that had developed in the place of side-branch struts, creating a neo-carina. CONCLUSIONS: At long-term BVS follow-up, we observed a favorable tissue response, with late luminal enlargement, side-branch patency, and development of a signal-rich, low-attenuating tissue layer that covered thrombogenic plaque components. The small size of the study and the observation of a different tissue response in 1 patient warrant judicious interpretation of our results and confirmation in larger studies.

Optical coherence tomography assessment of the spatial distribution of culprit ruptured plaques and thin-cap fibroatheromas in acute coronary syndrome.

AIMS: Plaque rupture and subsequent thrombosis is known to be the most important pathology leading to acute coronary syndrome (ACS). We investigated by optical coherence tomography (OCT) whether in ACS there is an association of the location of the culprit plaque in the coronary tree with plaque rupture and/or thin cap fibroatheroma (TCFA). METHODS AND RESULTS: We included 74 patients presenting with ACS that underwent OCT study of the culprit lesion. The distance of the culprit lesion from the ostium was measured angiographically, and the presence of rupture and/or TCFA was assessed by OCT. Sixty-seven patients were analysed. Forty-five ruptured plaques were identified by OCT (67.1%). The distance from the ostium was lower for culprit ruptured plaques versus culprit non-ruptured plaques (p<0.01), particularly in the left anterior descending (LAD) and the left circumflex (LCx) arteries. The majority of culprit ruptured plaques (68.9%) was located in the proximal 30 mm of the coronary arteries. A distance from the ostium of ≤30.54 mm predicted plaque rupture with 71.1% sensitivity and 68.2% specificity. Culprit lesions in the proximal 30 mm are associated with rupture (p<0.05), TCFA (p<0.05), and lower minimal cap thickness (p<0.05). CONCLUSIONS: Culprit ruptured plaques in ACS seem to be predominately located in the proximal segments of the coronary arteries.

Online 3-dimensional rendering of optical coherence tomography images for the assessment of bifurcation intervention.

Three-dimensional optical coherence tomography rendering has been suggested as a method providing additive information for the assessment of the result of percutaneous coronary intervention. However, rendering of such models is very time-consuming and cannot be performed online during the intervention. We present a case in which a new method for 3-dimensional rendering of optical coherence tomography images helped visualize the stent-vessel wall interaction, providing useful information that discouraged further intervention.

Pitfalls of angiography in the assessment of atherosclerosis: the role of optical coherence tomography.

We report the case of a patient presenting with unstable angina, in whom information obtained by coronary angiography was inconclusive for the existence of a culprit lesion in the ostium of the right coronary artery. The use of optical coherence tomography was required for proper lesion assessment.