Dual modality intravascular optical coherence tomography (OCT) and near-infrared fluorescence (NIRF) imaging: a fully automated algorithm for the distance-calibration of NIRF signal intensity for quantitative molecular imaging

Intravascular optical coherence tomography (IVOCT) is a well-established method for the high-resolution investigation of atherosclerosis in vivo. Intravascular near-infrared fluorescence (NIRF) imaging is a novel technique for the assessment of molecular processes associated with coronary artery disease. Integration of NIRF and IVOCT technology in a single catheter provides the capability to simultaneously obtain co-localized anatomical and molecular information from the artery wall. Since NIRF signal intensity attenuates as a function of imaging catheter distance to the vessel wall, the generation of quantitative NIRF data requires an accurate measurement of the vessel wall in IVOCT images. Given that dual modality, intravascular OCT–NIRF systems acquire data at a very high frame-rate (>100 frames/s), a high number of images per pullback need to be analyzed, making manual processing of OCT–NIRF data extremely time consuming. To overcome this limitation, we developed an algorithm for the automatic distance-correction of dual-modality OCT–NIRF images. We validated this method by comparing automatic to manual segmentation results in 180 in vivo images from six New Zealand White rabbit atherosclerotic after indocyanine-green injection. A high Dice similarity coefficient was found (0.97 ± 0.03) together with an average individual A-line error of 22 µm (i.e., approximately twice the axial resolution of IVOCT) and a processing time of 44 ms per image. In a similar manner, the algorithm was validated using 120 IVOCT clinical images from eight different in vivo pullbacks in human coronary arteries. The results suggest that the proposed algorithm enables fully automatic visualization of dual modality OCT–NIRF pullbacks, and provides an accurate and efficient calibration of NIRF data for quantification of the molecular agent in the atherosclerotic vessel wall.National Institutes of Health (U.S.) (NIH R01HL093717)Merck & Co., Inc

Two-Dimensional Intravascular Near-Infrared Fluorescence Molecular Imaging of Inflammation in Atherosclerosis and Stent-Induced Vascular Injury

ObjectivesThis study sought to develop a 2-dimensional (2D) intravascular near-infrared fluorescence (NIRF) imaging strategy for investigation of arterial inflammation in coronary-sized vessels.BackgroundMolecular imaging of arterial inflammation could provide new insights into the pathogenesis of acute myocardial infarction stemming from coronary atheromata and implanted stents. Presently, few high-resolution approaches can image inflammation in coronary-sized arteries in vivo.MethodsA new 2.9-F rotational, automated pullback 2D imaging catheter was engineered and optimized for 360° viewing intravascular NIRF imaging. In conjunction with the cysteine protease-activatable imaging reporter Prosense VM110 (VisEn Medical, Woburn, Massachusetts), intra-arterial 2D NIRF imaging was performed in rabbit aortas with atherosclerosis (n =10) or implanted coronary bare-metal stents (n = 10, 3.5-mm diameter, day 7 post-implantation). Intravascular ultrasound provided coregistered anatomical images of arteries. After sacrifice, specimens underwent ex vivo NIRF imaging, fluorescence microscopy, and histological and immunohistochemical analyses.ResultsImaging of coronary artery–scaled phantoms demonstrated 8-sector angular resolution and submillimeter axial resolution, nanomolar sensitivity to NIR fluorochromes, and modest NIRF light attenuation through blood. High-resolution NIRF images of vessel wall inflammation with signal-to-noise ratios >10 were obtained in real-time through blood, without flushing or occlusion. In atherosclerosis, 2D NIRF, intravascular ultrasound–NIRF fusion, microscopy, and immunoblotting studies provided insight into the spatial distribution of plaque protease activity. In stent-implanted vessels, real-time imaging illuminated an edge-based pattern of stent-induced arterial inflammation.ConclusionsA new 2D intravascular NIRF imaging strategy provides high-resolution in vivo spatial mapping of arterial inflammation in coronary-sized arteries and reveals increased inflammation-regulated cysteine protease activity in atheromata and stent-induced arterial injury

The effect of matrix metalloproteinase 2 and matrix metalloproteinase 2/9 deletion in experimental post-thrombotic vein wall remodeling

BackgroundVein wall fibrotic injury following deep venous thrombosis (VT) is associated with elevated matrix metalloproteinases (MMPs). Whether and by what mechanism MMP2 contributes to vein wall remodeling after VT is unknown.MethodsStasis VT was produced by ligation of the inferior vena cava and tissue was harvested at 2, 8, and 21 days in MMP2 -/- and genetic wild type (WT) mice. Tissue analysis by immunohistochemistry, enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and zymography was performed.ResultsThrombus resolution was less at 8 days in MMP2 -/- compared with WT, evidenced by a 51% increase in VT size (P < .01), and threefold fewer von Willebrand's factor positive channels (P < .05). In MMP2 -/- mice, the main phenotypic fibrotic differences occurred at 8 days post-VT, with significantly less vein wall collagen content (P = .013), fourfold lower procollagen III gene expression (P < .01), but no difference in procollagen I compared with WT. Decreased inflammation in MMP2 -/- vein walls was suggested by ∼ threefold reduced TNFα and IL-1β at 2 days and 8 days post-VT (P < .05). A fourfold increase in vein wall monocytes (P = .03) with threefold decreased apoptosis (P < .05), but no difference in cellular proliferation at 8 days was found in MMP2 -/- compared with WT. As increased compensatory MMP9 activity was observed in the MMP2 -/-mice, MMP2/9 double null mice had thrombus induced with VT harvest at 8 days. Consistently, twofold larger VT, a threefold decrease in vein wall collagen, and a threefold increase in monocytes were found (all P < .05). Similar findings were observed in MMP9 -/- mice administered an exogenous MMP2 inhibitor.ConclusionsIn stasis VT, deletion of MMP2 was associated with less midterm vein wall fibrosis and inflammation, despite an increase in monocytes. Consideration that VT resolution was impaired with MMP2 (and MMP2/9) deletion suggests direct inhibition will likely also require anticoagulant therapy.Clinical RelevancePost-thrombotic syndrome has no direct therapies and causes significant morbidity. Anticoagulation limits thrombosis but does not clinically impact directly the vein wall response to injury as well as has bleeding risks. In this experimental study, we show that matrix metalloproteinase 2 genetic deletion lessens fibrotic injury and inflammation at the midterm timepoint, yet is also important for thrombus resolution. Future therapies that positively impact vein wall remodeling will need to account for how the thrombus responds as well

Randomized Comparison of a CrossBoss First Versus Standard Wire Escalation Strategy for Crossing Coronary Chronic Total Occlusions: The CrossBoss First Trial

OBJECTIVES: The authors performed a multicenter, randomized-controlled, clinical trial comparing upfront use of the CrossBoss catheter versus antegrade wire escalation for antegrade crossing of coronary chronic total occlusions. BACKGROUND: There is equipoise about the optimal initial strategy for crossing coronary chronic total occlusions. METHODS: The primary endpoints were the time required to cross the chronic total occlusion or abort the procedure and the frequency of procedural major adverse cardiovascular events. The secondary endpoints were technical and procedural success, total procedure time, fluoroscopy time required to cross and total fluoroscopy time, total air kerma radiation dose, total contrast volume, and equipment use. RESULTS: Between 2015 and 2017, 246 patients were randomized to the CrossBoss catheter (n = 122) or wire escalation (n = 124) at 11 U.S. centers. The baseline clinical and angiographic characteristics of the study groups were similar. Technical and procedural success were 87.8% and 84.1%, respectively, and were similar in the 2 groups. Crossing time was similar: 56 min (interquartile range: 33 to 93 min) in the CrossBoss group and 66 min (interquartile range: 36 to 105 min) in the wire escalation group (p = 0.323), as was as the incidence of procedural major adverse cardiovascular events (3.28% vs. 4.03%; p = 1.000). There were no significant differences in the secondary study endpoints. CONCLUSIONS: As compared with wire escalation, upfront use of the CrossBoss catheter for antegrade crossing of coronary chronic total occlusions was associated with similar crossing time, similar success and complication rates, and similar equipment use and cost

Angiographic Features and Clinical Outcomes of Balloon Uncrossable Lesions during Chronic Total Occlusion Percutaneous Coronary Intervention

Background: Balloon uncrossable lesions are defined as lesions that cannot be crossed with a balloon after successful guidewire crossing. Methods: We analyzed the association between balloon uncrossable lesions and procedural outcomes of 8671 chronic total occlusions (CTOs) percutaneous coronary interventions (PCIs) performed between 2012 and 2022 at 41 centers. Results: The prevalence of balloon uncrossable lesions was 9.2%. The mean patient age was 64.2 ± 10 years and 80% were men. Patients with balloon uncrossable lesions were older (67.3 ± 9 vs. 63.9 ± 10, p < 0.001) and more likely to have prior coronary artery bypass graft surgery (40% vs. 25%, p < 0.001) and diabetes mellitus (50% vs. 42%, p < 0.001) compared with patients who had balloon crossable lesions. In-stent restenosis (23% vs. 16%. p < 0.001), moderate/severe calcification (68% vs. 40%, p < 0.001), and moderate/severe proximal vessel tortuosity (36% vs. 25%, p < 0.001) were more common in balloon uncrossable lesions. Procedure time (132 (90, 197) vs. 109 (71, 160) min, p < 0.001) was longer and the air kerma radiation dose (2.55 (1.41, 4.23) vs. 1.97 (1.10, 3.40) min, p < 0.001) was higher in balloon uncrossable lesions, while these lesions displayed lower technical (91% vs. 99%, p < 0.001) and procedural (88% vs. 96%, p < 0.001) success rates and higher major adverse cardiac event (MACE) rates (3.14% vs. 1.49%, p < 0.001). Several techniques were required for balloon uncrossable lesions. Conclusion: In a contemporary, multicenter registry, 9.2% of the successfully crossed CTOs were initially balloon uncrossable. Balloon uncrossable lesions exhibited lower technical and procedural success rates and a higher risk of complications compared with balloon crossable lesions

Use of the Limited Antegrade Subintimal Tracking Technique in Chronic Total Occlusion Percutaneous Coronary Intervention

BACKGROUND There are limited data on the limited antegrade subintimal tracking (LAST) technique for chronic total occlusion (CTO) percutaneous coronary intervention (PCI).OBJECTIVES The aim of this study was to analyze the frequency of use and outcomes of the LAST technique for CTO PCI.METHODS We analyzed 2,177 CTO PCIs performed using antegrade dissection and re-entry (ADR) in the PROGRESS-CTO (Prospective Global Registry for the Study of Chronic Total Occlusion Intervention) registry between 2012 and January 2022 at 39 centers. ADR was attempted in 1,465 cases (67.3%).RESULTS Among antegrade re-entry cases, LAST was used in 163 (11.1%) (primary LAST in 127 [8.7%] and secondary LAST [LAST after other ADR approaches failed] in 36 [2.5%]), the Stingray system (Boston Scientific) in 980 (66.9%), subintimal tracking and re-entry in 387 (26.4%), and contrast-guided subintimal tracking and re-entry in 29 (2.0%). The mean patient age was 65.2 similar to 10 years, and 85.8% were men. There was no significant difference in technical (71.8% vs 77.8%; P 1/4 0.080) and procedural (69.9% vs 75.3%; P 1/4 0.127) success and major cardiac adverse events (1.84% vs 3.53%; P 1/4 0.254) between LAST and non-LAST cases. However, on multivariable analysis, the use of LAST was associated with lower procedural success (OR: 0.61; 95% CI: 0.41-0.91). Primary LAST was associated with higher technical (76.4% vs 55.6%; P 1/4 0.014) and procedural (75.6% vs 50.0%; P 1/4 0.003) success and similar major adverse cardiac event (1.57% vs 2.78%; P 1/4 0.636) rates compared with secondary LAST.CONCLUSIONS LAST was used in 11.1% of antegrade re-entry CTO PCI cases and was associated with lower procedural success on multivariable analysis, suggesting a limited role of LAST in contemporary CTO PCI. (J Am Coll Cardiol Intv 2022;15:2284-2293) (c) 2022 by the American College of Cardiology Foundation

Prevalence and Outcomes of Percutaneous Coronary Interventions for Ostial Chronic Total Occlusions: Insights From a Multicenter Chronic Total Occlusion Registry

Ostial chronic total occlusions (CTOs) can be challenging to recanalize.We sought to examine the prevalence, angiographic presentation, and procedural outcomes of ostial (side-branch ostial and aorto-ostial) CTOs among 1000 CTO percutaneous coronary interventions (PCIs) performed in 971 patients between 2015 and 2017 at 14 centres in the US, Europe, and Russia.Ostial CTOs represented 16.9% of all CTO PCIs: 9.6% were aorto-ostial, and 7.3% were side-branch ostial occlusions. Compared with nonostial CTOs, ostial CTOs were longer (44 ± 33 vs 29 ± 19 mm, P < 0.001) and more likely to have proximal-cap ambiguity (55% vs 33%, P < 0.001), moderate/severe calcification (67% vs 45%, P < 0.001), a diffusely diseased distal vessel (41% vs 26%, P < 0.001), interventional collaterals (64% vs 53%, P = 0.012), and previous coronary artery bypass graft surgery (CABG) (51% vs 27%, P < 0.001). The retrograde approach was used more often in ostial CTOs (54% vs 29%, P < 0.001) and was more often the final successful crossing strategy (30% vs 18%, P = 0.003). Technical (81% vs 84%, P = 0.280), and procedural (77% vs 83%, P = 0.112) success rates and the incidence of in-hospital major complication were similar (4.8% vs 2.2%, P = 0.108), yet in-hospital mortality (3.0% vs 0.5%, P = 0.010) and stroke (1.2% vs 0.0%, P = 0.030) were higher in the ostial CTO PCI group. In multivariable analysis, ostial CTO location was not independently associated with higher risk for in-hospital major complications (adjusted odds ratio 1.27, 95% confidence intervals 0.37 to 4.51, P = 0.694).Ostial CTOs can be recanalized with similar rates of success as nonostial CTOs but are more complex, more likely to require retrograde crossing and may be associated with numerically higher risk for major in-hospital complications

In-hospital Outcomes of Attempting More Than One Chronic Total Coronary Occlusion Through Percutaneous Intervention During the Same Procedure

The frequency and outcomes of patients who underwent chronic total occlusion (CTO) percutaneous coronary intervention (PCI) of more than one CTO during the same procedure have received limited study. We compared the clinical and angiographic characteristics and procedural outcomes of patients who underwent treatment of single versus >1 CTOs during the same procedure in 20 centers from the United States, Europe, and Russia. A total of 2,955 patients were included: mean age was 65 ± 10 years and 85% were men with high prevalence of previous myocardial infarction (46%), and previous coronary artery bypass graft surgery (33%). More than one CTO lesions were attempted during the same procedure in 58 patients (2.0%) and 70% of them were located in different major epicardial arteries. Compared with patients who underwent PCI of a single CTO, those who underwent PCI of >1 CTOs during the same procedure had similar J-CTO (2.4 ± 1.3 vs 2.5 ± 1.3, p = 0.579) and Prospective Global Registry for the Study of Chronic Total Occlusion Intervention (1.5 ± 1.2 vs 1.3 ± 1.0 p = 0.147) scores. The multi-CTO PCI group had similar technical success (86% vs 87%, p = 0.633), but higher risk of in-hospital major complications (10.3% vs 2.7%, p = 0.005), and consequently numerically lower procedural success (79% vs 85%, p = 0.197). The multi-CTO PCI group had higher in-hospital mortality (5.2% vs 0.5%, p = 0.005) and stroke (5.2%vs 0.2%, p 1 CTO lesions requiring revascularization, as treatment during a single procedure was associated with higher risk for periprocedural complications