Intravascular ultrasound lumen area parameters for assessment of physiological ischemia by fractional flow reserve in intermediate coronary artery stenosis

BackgroundA fractional flow reserve (FFR) of <0.8 is currently used to guide revascularization in lesions with intermediate coronary stenosis. Whether there is an intravascular ultrasound (IVUS) measurement or a cutoff value that can reliably determine which of these intermediate lesions requires intervention is unclear.AimsWe assessed IVUS measurement accuracy in defining functional ischemia by FFR.MethodsThe analysis included 205 intermediate lesions (185 patients) located in vessel diameters >2.5 mm. Positive FFR was considered present at <0.8. IVUS measurements were correlated to the FFR findings in intermediate lesions with 40%–70% stenosis. Fifty-four (26.3%) lesions had FFR<0.8.ResultsThere was moderate correlation between FFR and IVUS measurements, including minimum lumen area (MLA) (r=0.36, P<.001), minimum lumen diameter (MLD) (r=0.25, P=<.001), lesion length (r=?0.43, P<.001), and area stenosis (r=?0.33, P=.01). A receiver operating characteristic curve (ROC) identified MLA<3.09 mm² (sensitivity 69.2%, specificity 79.5%) as the best threshold value for FFR<0.8. The correlation between FFR and IVUS was better for large vessels compared to small vessels. ROC analysis identified the best threshold value for FFR<0.8 of MLA<2.4 mm² [area under curve (AUC)=0.74] in lesions with reference vessel diameters of 2.5–3 mm, MLA<2.7 mm² (AUC=0.77) in lesions with reference vessel diameters of 3–3.5 mm, and MLA<3.6 mm² (AUC=0.70) in lesions with reference vessel diameters >3.5 mm.ConclusionAnatomic measurements of intermediate coronary lesions obtained by IVUS show a moderate correlation to FFR values. The correlation was better for larger-diameter vessels. Vessel size should always be taken into account when determining the MLA associated with functional ischemia.     

Intravascular ultrasound assessment of distal left main bifurcation disease: The importance of the polygon of confluence of the left main,left anterior descending,and left circumflex arteries

Background : The polygon of confluence (POC) represents the zone of confluence of the distal left main (LM), ostial left anterior descending (LAD), and ostial left circumflex (LCX) arteries. Methods : We used intravascular ultrasound (IVUS) to assess the POC pre and post‐drug‐eluting stent implantation for unprotected distal LM disease. Four segments within 82 LM bifurcation lesions were defined by longitudinal IVUS reconstruction: (1) ostial LAD, (2) POC, and (3) distal LM (DLM)—from LAD‐pullback, and (4) ostial LCX from LCX‐pullback. Results : Preprocedural minimum lumen area (MLA) and poststenting minimum stent area (MSA) within the LM were mainly located within the POC (51 and 71%). On ROC analysis, a cut‐off of the MLA within the POC of 6.1 mm² predicted significant LCX carinal stenosis (85% sensitivity, 52% specificity, AUC = 0.7, 95% CI = 0.57–0.78, P < 0.01). Poststenting MSA within the distal LM proximal to the carina (to include DLM and POC) positively correlated with the preprocedural MLA within the POC (r = 0.283, P = 0.02); it was significantly smaller in 48 lesions with a pre‐PCI MLA within the POC < 6.1 mm² versus 25 lesions with a pre‐PCI MLA ≥6.1 mm² (7.5 ± 2.1 mm² vs. 8.6 ± 2.0 mm², P = 0.04). Independent predictors for poststenting LCX carinal MLA also included preprocedural MLA within the POC (β = 0.240, 95% CI = 0.004–0.353, P = 0.04). Conclusion : The MLA within the POC was a good surrogate reflecting the overall severity of LM bifurcation disease including ostial LCX stenosis pre‐PCI and the ability to expand a stent within the distal LM as well as final ostial LCX lumen area post‐PCI. © 2011 Wiley Periodicals, Inc.     

Angiographically silent left main disease detected by intravascular ultrasound: a marker for future adverse cardiac events

Background

Concomitant moderate obstructive left main (LM) disease is associated with future cardiac events and poor prognosis in patients undergoing percutaneous intervention (PCI). Whether prognosis is similarly effected by LM disease not detected by angiography, but evident on intravascular ultrasound (IVUS) imaging, is not known. The purpose of this study was to evaluate the long-term prognosis of patients with angiographically insignificant LM coronary artery disease undergoing PCI.

Methods and results

One hundred and seven consecutive patients undergoing PCI with angiographically normal or mild LM disease had 2- and 3-dimensional IVUS imaging. IVUS images were digitized, and 3-dimensional reconstruction was performed. Percent diameter and area stenosis by angiography were 4.8% ± 3.5% and 18.2% ± 9.8%, respectively. IVUS mean luminal area and area stenosis were 17.9 ± 5.6 mm² and 30.2% ± 14.7%, respectively. Long-term follow-up was available in 102 (95%) patients at a median of 29 (range 8-52) months. Major adverse cardiac events, defined as death (6), myocardial infarction (4), repeat PCI (13), or CABG (16), were associated with female sex (P = .04), diabetes (P = .02), angiographic minimum lumen diameter (P = .04), and IVUS minimum (P = .01) and mean (P = .01) lumen area. Multivariate predictors of late cardiac events were diabetes (hazard ratio 2.69, P = .014) and minimum lumen area by IVUS (hazard ratio 0.59, P = .015).

Conclusions

Despite being angiographically silent, LM disease detected by IVUS is an independent predictor of cardiac events and may serve as a marker for such events. These data extend the spectrum of LM disease severity and its relationship to cardiac prognosis in patients undergoing PCI.     

Intravascular ultrasound imaging after excimer laser angioplasty

To help elucidate the mechanism of excimer laser coronary angioplasty (ELCA), intra-vascular ultrasound (IVUS) imaging was performed in 19 of 29 patients who were treated with ELCA. The results were compared with a non-randomized control group of 18 patients who had IVUS studies both before and after PTCA alone. After ELCA alone, lumen diameter (1.9 × 1.7 mm) and lumen cross-sectional area (CSA) (2.9 mm²) by IVUS were not significantly different from baseline values in the patients before PTCA alone (2.1 × 1.8 mm, 3.2 mm²). After balloon dilatation in the laser treated group, lumen diameter (2.5 × 2.1 mm) and lumen CSA (4.9 mm²) were significantly greater than those post ELCA alone. However, there was no difference in lumen CSA or atheroma CSA in the group treated with excimer laser plus balloon dilatation vs. these measurements in the group treated with PTCA alone. ELCA does not ablate a large amount of atheroma (9% reduction) but creates a pathway to permit easier passage of a PTCA balloon. These quantitative and morphologic results may help explain why the restenosis rate with ELCA is similar to PTCA alone. © 1994 Wiley-Liss,Inc..     

Early time course of neointima formation and vascular remodelling following percutaneous coronary intervention and vascular brachytherapy of in-stent restenotic lesions as assessed by intravascular ultrasound analysis

Summary In-stent restenosis (ISR) represents the major limitation of stent implantation. Treatment, although of relative technical ease, is unsatisfactory due to a high incidence of recurrent restenosis. Vascular brachytherapy (VBT) has emerged as a powerful adjunct therapeutic modality to treat ISR. Inhibition of neointima formation has been regarded as the relevant mechanism of action. Yet, positive remodelling has been suspected as another contributing factor. Since only very few precise analyses of the extent, distribution and time course of the respective mechanims exist, the goal of the present study was to describe the changes of the vessel geometry at the target lesion and at the reference site following angioplasty and VBT of ISR in 42 patients by means of quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS) before and after the index procedure and at the 3 and 6 month follow-up.By QCA the acute lumen gain measured 2.2±0.8 mm, the late lumen loss at 3 months was 0.1±0.5 mm and at 6 months 0.4±0.7 mm. By IVUS luminal cross-sectional area increased from 1.5±1.2 mm² to 7.9±1.9 mm² (p<0.001). The intima hyperplasia cross-sectional area at 3 months was only 0.2±1.0 mm² (p=0.191), but increased to 0.7±0.6 mm² (p<0.001) at 6 months resulting in a lumen cross-sectional area of 7.1±1.7 mm². Stent dimensions did not show any significant changes over time. The external elastic membrane cross-sectional area at 3 months increased by 1.3±1.9 mm² (p<0.001), and showed a further increase by 0.7±2.9 mm² at 6 months. Positive remodelling could be demonstrated also at the reference segment.In conclusion the absolute amount of intima hyperplasia during a 6-month follow-up period after VBT of ISR is low and most pronounced between the third and sixth month. Besides this, predominantly within the first 3 months of follow-up, significant positive remodelling could be demonstrated at the target lesion and at the reference site. Both observed effects may contribute to the preservation of the vessel lumen.Diese Publikation enthält die Ergebnisse der Promotionsarbeit von Frau Andrea Zimmermann     

What Is an Appropriate Reference Standard in the Quantitation of Plaque Surface Area by Intravascular Coronary Ultrasound?

We reevaluate the predictive accuracy of intravascular ultrasound (IVUS)-derived per cent plaque area stenosis (PAS) in significant coronary lesions (CLs) with or without proximal and distal reference vessel area adjustment. IVUS is valuable in defining moderate CL severity (30 to 70%) in left main (LM) or non-left main (NLM) coronaries using minimum luminal area (MLA) of ≤5.9 and ≤4 mm², respectively. Despite a strong correlation with severe CLs, PAS (≥ 70% for NLM and ≥67% for LM) remains underutilized because of confusion about an appropriate reference standard. We studied 120 patients with symptomatic moderate CLs (74 NLM, 46 LM) who underwent IVUS. In-lesion and adjusted PAS were derived by subtracting MLA from in-lesion and proximal or distal reference''s external elastic membrane (EEM) area, respectively, divided by corresponding EEM area multiplied by 100. In-lesion PAS was correlated with MLA cutoffs of ≤5.9 and ≤7.5 mm² for LM and ≤4 mm² for NLM. Adjusted PAS strongly correlated with in-lesion PAS irrespective of reference segment (proximal reference, r = 0.879, p < 0.001; distal reference, r = 0.833, p < 0.001; mean proximal and distal reference, r = 0.896, p < 0.001). Considering MLA of ≤4 mm² (for NLM) and ≤5.9 mm² (for LM), in-lesion PAS of ≥70 and ≥67%, respectively, explained the majority of severe CLs but the sensitive LM MLA cutoff of ≤7.5 mm² showed higher predictive accuracy. Based on results, both in-lesion PAS and adjusted PAS can be used interchangeably and correlate strongly with MLA.     

Impact of geographic miss on adjacent coronary artery segments in diffuse in-stent restenosis with beta-radiation therapy: angiographic and intravascular ultrasound analysis

Background The impacts of geographic miss on edge restenosis have not been sufficiently evaluated. Methods β-Radiation therapy with rhenium 188-filled balloon after rotational atherectomy for diffuse in-stent restenosis was performed in 50 patients. We evaluated the impacts of geographic miss on adjacent coronary artery segments beyond the stent by angiographic (QCA) and intravascular ultrasound (IVUS) analysis in 50 irradiated lesions and 100 edges. Serial IVUS and QCA comparisons between postradiation and 6 months' follow-up were available in 44 and 47 of 50 patients, respectively. QCA measurements of minimal lumen diameter (MLD) and IVUS analysis were performed in the reference and radiation segments. Edges that were touched by the angioplasty balloon but were not adequately covered by radiation constituted the geographic miss edges. Results Geographic miss was observed in 55.6% and 52.6% in QCA and IVUS analysis, respectively. Edge restenosis after radiation therapy in 3 patients was associated with geographic miss. In contrast to uninjured edges (postradiation 2.9 ± 0.6 mm to follow-up 2.8 ± 0.6 mm, P = .292), MLD in the radiation segment by QCA analysis significantly decreased from 2.7 ± 0.4 mm to 2.4 ± 0.6 mm in geographic miss edges (P = .002). IVUS analysis showed that significant positive remodeling in the radiation segment occurred in uninjured edges (vessel area from 15.4 ± 4.4 mm² to 15.8 ± 4.4 mm², P = .001) but not in geographic miss edges (vessel area from 12.8 ± 3.6 mm² to 13.0 ± 3.6 mm², P = .119). Conclusion The geographic miss might be one of the predictors, which resulted in decreased MLD at follow-up in β-radiation therapy. Sufficient lesion coverage with radiation might be associated with positive remodeling in the radiation segment. (Am Heart J 2002;143:327-33.)     

Serial intravascular ultrasound analysis comparing double kissing and classical crush stenting for coronary bifurcation lesions

Background : Compared with the classical crush, double kissing (DK) crush improved outcomes in patients with coronary bifurcation lesions. However, there is no serial intravascular ultrasound (IVUS) comparisons between these two techniques. Objectives : This study aimed to analyze the mechanisms of the two crush stenting techniques using serial IVUS imaging. Methods : A total of 54 patients with IVUS images at baseline, post‐stenting and eight‐month follow‐up were classified into classical (n = 16) and DK (n = 38) groups. All patients underwent final kissing balloon inflation (FKBI). Unsatisfactory kissing (KUS) was defined as the presence of wrist or >20% stenosis during FKBI at the side branch (SB) ostium. The vessels at bifurcation lesions were divided into the proximal main vessel (MV) stent, the crushed segment, the distal MV stent, the SB ostium and the SB stent body. Results : KUS and incomplete crushing were commonly observed in the classical group (62.5%, 81.3%), compared with DK group (18.0%, 39.5%, P < 0.001 and P = 0.004). The post‐stenting stent symmetry in the classical group was 71.85 ± 7.69% relative to 85.93 ± 6.09% in DK group (P = 0.022), resulting in significant differences in neointimal hyperplasia (NIH, 1.60 ± 0.21 mm² vs. 0.85 ± 0.23 mm², P = 0.005), late lumen loss (1.31 ± 0.81 mm² vs. 0.55 ± 0.70 mm², P = 0.013), and minimal lumen area (MLA, 3.57 ± 1.52 mm² vs. 4.52 ± 1.40 mm^2, P = 0.042) at the SB ostium between two groups. KUS was positively correlated with the incomplete crush and was the only predictor of in‐stent‐restenosis (ISR) at the SB ostium. Conclusion : DK crush was associated with improved quality of the FKBI and larger MLA. KUS predicted the occurrence of ISR. © 2011 Wiley Periodicals, Inc.     

First Report of Edge Vascular Response at 12 Months of Magmaris,A Second-Generation Drug-Eluting Resorbable Magnesium Scaffold,Assessed by Grayscale Intravascular Ultrasound,Virtual Histology,and Optical Coherence Tomography. A Biosolve-II Trial Sub-Study

Introduction and objectiveThe edge vascular response (EVR) remains unknown in second generation drug-eluting Resorbable Magnesium Scaffold (RMS), such as Magmaris. The aim of the study was to evaluate tissue modifications in the RMS edges over time, assessed by different invasive imaging modalities.MethodsThe patients treated with the device were assessed by optical coherence tomography (OCT), grayscale intravascular ultrasound (IVUS), and virtual histology IVUS at baseline and 12 months. The EVR study performed a segment- and frame-level analysis of the 5 mm segments proximal and distal of the actual RMS.ResultsThe segment-level grayscale IVUS (n = 10), virtual histology IVUS (n = 10), and OCT (n = 18) analysis did not show any significant changes after 12 months, except for a fibrous plaque area (FPA) reduction of 0.5mm² (p = 0.017) in the proximal segment compared to baseline. In the frame-level analysis, IVUS evaluation revealed a vessel area decreased 2.80 ± 1.43 mm² (p = 0.012) and 2.49 ± 1.53 mm² (p = 0.022) in 2 proximal frames. This was accompanied by plaque area reduction of 0.88 ± 0.70 mm² (p = 0.048) and a FPA decreased by 0.63 ± 0.48 mm² (p = 0.004) in one proximal frame. In 1 distal frame, there was a dense calcium area reduction of 0.10 ± 0.12 mm² (p = 0.045), FPA and fibrous fatty plaque increased 0.54 ± 0.53 mm² (p = 0.023) and 0.17 ± 0.16 mm² (p = 0.016), respectively. By OCT, there was a lumen area decrease of 0.76 ± 1.51 mm² (p = 0.045) in a distal frame.ConclusionAt 12 months, Magmaris EVR assessment does not show overall significant changes, except for a fibrous plaque area reduction in the proximal segment. This could be translated as a benign healing process at the edges of the RMS.SummaryThe edge vascular response (EVR) remains unknown in second generation drug-eluting absorbable metal scaffolds (RMS), such as Magmaris. Patients treated with the device were assessed by multi invasive imaging modalities [i.e. optical coherence tomography (OCT), grayscale intravascular ultrasound (IVUS), and virtual histology IVUS] evaluating the tissue changes over time in the segment- and frame-level analysis of the 5 mm segments proximal and distal of the actual RMS. As a result, after 12 months, Magmaris EVR assessment does not show overall significant changes, except for a fibrous plaque area reduction in the proximal segment, translating a benign healing process at the edges of the RMS.     

Intravascular Ultrasound-Derived Minimal Lumen Area Criteria for Functionally Significant Left Main Coronary Artery Stenosis

ObjectivesThis study sought to evaluate the intravascular ultrasound (IVUS) minimal lumen area (MLA) for functionally significant left main coronary artery (LMCA) stenosis using fractional flow reserve (FFR) as the standard.BackgroundThe evaluation of significant LMCA stenosis remains challenging.MethodsWe identified 112 patients with isolated ostial and shaft intermediate LMCA stenosis (angiographic diameter stenosis of 30% to 80%) who underwent IVUS and FFR measurement.ResultsThe FFR was ≤0.80 in 66 LMCA lesions (59%); these exhibited smaller reference vessels, smaller minimal lumen diameter, greater diameter of stenosis, longer lesion length, smaller MLA, larger plaque burden, and more frequent plaque rupture. The independent factors of an FFR of ≤0.80 were plaque rupture (odds ratio [OR]: 4.47; 95% Confidence Interval (CI): 1.35 to 14.8; p = 0.014); body mass index (OR: 1.19; 95% CI: 1.00 to 1.41; p = 0.05), age (OR: 0.95; 95% CI: 0.90 to 1.00; p = 0.031), and IVUS MLA (OR: 0.37; 95% CI: 0.25 to 0.56; p < 0.001). The optimal IVUS MLA cutoff value for an FFR of ≤0.80 was 4.5 mm² (77% sensitivity, 82% specificity, 84% positive predictive value, 75% negative predictive value, area under the curve: 0.83, 95% CI: 0.76 to 0.96; p < 0.001) overall and 4.1 to 4.5 mm² in various subgroups. Adjustment for the body surface area, body mass index, and left ventricular mass did not improve the diagnostic accuracy of the IVUS MLA.ConclusionsIn patients with isolated ostial and shaft intermediate LMCA stenosis, an IVUS-derived MLA of ≤4.5 mm² is a useful index of an FFR of ≤0.80.     

Intravascular ultrasound and 3D angle measurements of coronary bifurcations

Objective: To standardize the intravascular ultrasound (IVUS) analysis of coronary bifurcations. Background: Percutaneous treatment of bifurcation lesions is difficult particularly at the side branch ostium. Imaging techniques may improve our understanding of treatment options. There is no established IVUS methodology to assess the bifurcation. The present study aims to develop standards for bifurcation imaging. Methods: Quantitative IVUS analysis and 3D bifurcation angle measurements were performed in 34 patients who were selected from the Washington Hospital Center Database. Patients were included if both left anterior descending (LAD) and first diagonal (DX) pullbacks in the same procedure were done. Angiograms were available in 27 patients to measure the 3D bifurcation angle using specialized software. Pullbacks were analyzed proximal and distal to the bifurcation, and at the bifurcation. Results: Prox_LAD versus Prox_LAD(DX) were similar for vessel area (15.5 ± 4.6 mm² vs. 15.9 ± 4.0 mm², P = 0.19), lumen area (8.3 ± 3.6 mm² vs. 8.6 ± 3.3 mm², P = 0.25), and plaque area (7.2 ± 2.0 mm² vs. 7.3 ± 1.9 mm², P = 0.55). However, Bifurcation_LAD was larger than Bifurcation_DX for vessel area (17.3 ± 4.0 mm² vs. 16.6 ± 3.9 mm², P = 0.0083). The 3D angiographic bifurcation angle was 50° ± 13° (range of 26°–84°), and did not affect the IVUS measurements. IVUS analysis showed that bifurcation lesions did obey Murray's Law, as Prox_LAD lumen area measured 36.7 ± 25.1 mm³ versus Dist_LAD/Dist_DX measured 38.0 ± 29.1 mm³, P = 0.56. Conclusions: Two IVUS pullbacks should be performed for a complete assessment of the bifurcation and comparison with Murray's Law. The proposed IVUS analysis was not influenced by the bifurcation angle. © 2009 Wiley‐Liss, Inc.     

Mechanism of lumen gain with a novel rotational aspiration atherectomy system for peripheral arterial disease: examination by intravascular ultrasound

ObjectiveThe purpose of this study was to evaluate the mechanism of luminal gain with a novel atheroablation system (Pathway PV) for the treatment of peripheral artery disease using intravascular ultrasound (IVUS).MethodsThe atherectomy system is a rotational atherectomy device, which employs expandable rotating blades with ports that allow flushing and aspiration of the plaque material or thrombus. In this first-in-man clinical study, IVUS analysis was available in 6 patients with lower limb ischemia treated with this device. The treatment results were assessed using IVUS at pre and post atherectomy. Lumen beyond burr size (LBB) was defined as lumen gain divided by the estimated burr area determined by the burr-size.ResultsIVUS analysis was available in six patients (superficial femoral artery n=3, popliteal artery n=2, posterior tibial artery n=1). Atheroablation achieved a significant increase in lumen area (LA) (preintervention 3.9±0.4, postatheroablation 8.0±1.7 mm², P<.05), and significant reduction in plaque area (27.5±4.0, 23.7±3.1 mm², P=.001), while there was no change in the vessel area (31.3±4.2, 32.1±2.8 mm², P=.4). LBB was 57.4±51.3%.ConclusionThis novel rotational aspiration atherectomy device achieved significant luminal gain by debulking in the absence of vessel stretching. The LA was greater than burr-sized lumen expectancy at cross-sections along the treated segments, suggesting a complimentary role of aspiration in luminal gain in atherosclerotic peripheral artery lesions.     

Coronary artery size in North Indian population – Intravascular ultrasound-based study

ObjectiveThe coronary artery dimensions have important diagnostic and therapeutic implications in management of coronary artery disease (CAD). There is paucity of data on the coronary artery size in the Indian population as measured by intravascular ultrasound (IVUS).MethodsA total of 303 patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) with intravascular ultrasound underwent analysis along with quantitative coronary angiography (QCA). Of the 492 proximal coronary segments; 221 relating to left main (LM), 164 to left anterior descending artery (LAD), 45 to left circumflex artery (LCX), and 62 to right coronary artery (RCA) were considered.ResultsPatient's mean age was 53.37 ± 3.5 years; men 80%; hypertension 35% and diabetes 24.8%. On IVUS, mean minimal lumen diameter as compared to QCA in LM (4.60 mm versus 4.50 mm, p < 0.001), LAD (3.71 mm versus 3.45 mm, p < 0.001), LCX (3.55 mm versus 3.16 mm, p < 0.001) and RCA (3.85 mm versus 3.27 mm, p < 0.001) were significantly larger. Lumen and external elastic membrane (EEM) cross-sectional area (CSA) were larger in males as compared to females with statistical significance for lumen CSA in LM (p = 0.04); RCA (p = 0.02) and EEM CSA in LM (p = 0.03); RCA (p = 0.006) but no significance for adjusted body surface area (BSA). In multivariate models, BSA and age were independent predictors of LM and LAD diameters and areas, but age was an independent predictor indexed to BSA.ConclusionThe coronary artery dimensions by IVUS are significantly larger than QCA. No gender difference in coronary artery size. Age was an independent predictor of coronary artery size in left main and LAD. The coronary artery size may not be a risk factor for acute coronary syndrome.     

Reproducibility of intravascular ultrasound iMAP for radiofrequency data analysis: Implications for design of longitudinal studies

Background : iMAP is a new intravascular ultrasound (IVUS) derived technique for tissue characterization using spectral analysis. Since there is a need for reproducibility data to design longitudinal studies, we sought to assess the in vivo reproducibility of this imaging technique. Methods : iMAP (40 MHz, Boston Scientific Corporation) was performed in patients referred for elective percutaneous intervention and in whom a nonintervened vessel was judged suitable for a safe IVUS analysis. Overall 20 patients with 20 non‐angiographically significant lesions were assessed by two independent observers. Five of these 20 patients received an additional iMAP analysis using a new IVUS catheter and using the same catheter after its engagement and reengagement. Results : The interobserver relative difference in plaque area was 2.5%. Limits of agreement for lumen, vessel, and plaque area measurements were 1.62, ?2.47 mm²; 2.09, ?3.71 mm²; 2.80, ?3.72 mm²; respectively. Limits of agreement for fibrotic, lipidic, necrotic, and calcified measurements were 1.32, ?1.44 mm²; 0.24, ?0.36 mm²; 1.50, ?2.26 mm²; 0.09, ?0.11 mm²; respectively. The intercatheter and intracatheter relative difference in plaque area were 0.9% and 4.1%, respectively. Although the variability for compositional measurements increased using two different catheters or using the same catheter twice, the variability for compositional measurements keeps always below 10%. Conclusions : Our analysis demonstrates that the geometrical and compositional iMAP analysis is acceptably reproducible. © 2011 Wiley Periodicals, Inc.     

Impact of Nonobstructive Left Main Coronary Artery Atherosclerosis on Long-Term Mortality

BackgroundAlthough the presence of severe stenosis in the left main coronary artery (LMCA) is a well-established predictor of mortality, whether this extends to nonobstructive atherosclerosis in the LMCA is unknown.ObjectivesThe aim of this study was to evaluate the association between LMCA disease by intravascular ultrasound (IVUS) and long-term mortality.MethodsBetween 2005 and 2013, 3,239 patients with LMCA IVUS imaging without LMCA revascularization (either before angiography or scheduled based on index angiography or IVUS) were included. The primary and secondary endpoints were all-cause and cardiac mortality at a minimum of 5 years obtained from the National Death Index.ResultsThe IVUS-measured LMCA minimum lumen area (MLA) and plaque burden were 13.1 ± 5.0 mm² and 41.7% ± 15.6%, respectively. The median follow-up was 8.2 years. The Kaplan-Meier estimated 12-year all-cause and cardiac death rates were 37.5% and 17.0%, respectively. Greater plaque burden (unadjusted HR per 10%: 1.17; 95% CI: 1.12-1.22; P < 0.0001) and smaller IVUS MLA (unadjusted HR per 1 mm²: 0.98; 95% CI: 0.96-0.99; P = 0.0008) were associated with all-cause death. After adjusting for clinical, angiographic, and IVUS factors, plaque burden (adjusted HR per 10%: 1.12; 95% CI: 1.04-1.21; P = 0.003) but not MLA (adjusted HR per 1 mm²: 1.02; 95% CI: 0.99-1.04; P = 0.18) was associated with long-term all-cause death. These findings were also consistent for long-term cardiac mortality.ConclusionsIn the present large-scale study with a 12-year follow-up, increasing LMCA plaque burden was associated with long-term all-cause and cardiac mortality in patients not undergoing LMCA revascularization, even when the lumen area was preserved.     

Gravedad de la enfermedad coronaria definida por ultrasonido intravascular o tomografía de coherencia óptica y su relación con los índices fisiológicos

Introduction and objectivesFractional flow reserve or instantaneous wave-free ratio has become a standard criterion for revascularization. We sought to evaluate the association between intravascular ultrasound (IVUS) or optical coherence tomography (OCT)-derived quantitative plaque characteristics and the severity of physiologic stenosis.MethodsA total of 365 stenoses from 330 patients were evaluated. The association between IVUS or OCT-derived parameters and resting physiologic indices (instantaneous wave-free ratio, resting full-cycle ratio, and diastolic pressure ratio) and fractional flow reserve were explored.ResultsAmong the total number of lesions, 50.7% and 58.1% showed an instantaneous wave-free ratio ≤ 0.89 and fractional flow reserve ≤ 0.80, respectively. IVUS or OCT-derived parameters showed significant correlations with resting physiologic indices (P values < .005). The best cutoff values of IVUS minimum lumen area (MLA), plaque burden, OCT-MLA, and OCT-area stenosis to predict functional significance were the same (IVUS-MLA: 3.4 mm², plaque burden: 72.0%, OCT-MLA: 2.0 mm², OCT-area stenosis: 68.0%) for all resting physiologic indices (instantaneous wave-free ratio, resting full-cycle ratio, and diastolic pressure ratio). The best cutoff values for fractional flow reserve were an IVUS-MLA of 3.8 mm², plaque burden of 70.0%, OCT-MLA of 2.3 mm², and OCT-area stenosis of 65.0%. Regardless of IVUS or OCT-derived parameters, the overall diagnostic accuracies of the parameters were lower than 70% and discrimination indices were less than 0.75 for resting physiologic indices or fractional flow reserve.ConclusionsThe resting physiologic indices showed an identical relationship with IVUS or OCT-defined quantitative plaque characteristics. The diagnostic accuracy and discrimination ability of anatomical parameters were modest in predicting functional significance defined by resting and hyperemic invasive physiologic indices.This trial is registered at ClinicalTrials.gov (Identifier: NCT03795714).     

Assessment of optimum stent deployment by stent boost imaging: comparison with intravascular ultrasound

Stent boost (SB) imaging is an enhancement of the radiologic edge of the stent by digital management of regular X-ray images. The purpose of the present study was to validate SB imaging by comparison with the anatomical standard using intravascular ultrasound (IVUS). We investigated SB and IVUS after stent implantation in 68 arteries in 60 patients. Based on those findings, we added high-pressure dilatation in four patients and another stent implantation in four patients. We defined the SB criteria for adequate stent deployment as: complete stent expansion, stent minimum diameter ≥70% of reference diameter, and stent minimum diameter ≥2.0 mm; and IVUS criteria for adequate stent deployment as: minimal stent area ≥5.0 mm². If the reference vessel was <2.8 mm, adequate stent deployment was defined as minimum stent area ≥4.5 mm². IVUS findings indicated inadequate stent deployment in 21/72 observations (29%). Seven SB images showed inadequate stent expansion. SB predicted inadequate findings of IVUS with 100% specificity, 33% sensitivity, and 81% agreement. Although the sensitivity of SB image for adequate stent deployment is low, the specificity is sufficiently high for it to be the first-line for monitoring just after stent implantation in centers where IVUS is not used routinely.     

Importance of calibration for diameter and area determination by intravascular ultrasound

Background: Intravascular ultrasound (IVUS) permits quantitative assessment of the lumen diameter and area of coronary arteries. The experimental study was performed to evaluate the accuracy of diameter and area measurements.Methods and results: Lumen quantitation (lumen diameter D and cross-sectional area A) in lucite tubes (lumen diameter 2.5 to 5.7 mm, Plexiglas) was performed using a mechanical IVUS system (HP console, 3.5F catheter, Boston Scientific, 30 MHz). The influence of fluid type (blood, water and saline solution), fluid temperature (20°C/37°C), catheter to catheter variation, gain setting and ultrasound frequency (12, 20 and 30 MHz) was determined. In blood at 20°C there was a constant deviation of the measured diameter from the true luminal diameter of –0.29 ± –0.04 mm (p<0.06). In water and saline solution at 20°C the mean deviation from true diameter was –0.21 ± –0.06 mm (p<0.06). At 37°C, the deviation in blood was greater than at 20° (–0.34 ± –0.02 mm) which is >10% in a 3mm tube (p<0.06). Three of the ten catheters tested in water at 20°C underestimated true diameter by more than –0.3 mm. The deviation from true diameter (5mm tube) with varying gain settings was –0.14 mm to –0.23 mm compared to –0.19 mm at standard settings (p>0.288). At 12 MHz diameter measured was over-estimated. The error in absolute area estimation increased with increasing diameter tested in blood at 37°C (–1.21 to –2,72mm²), whereas the relative error ([Measured Area-True Area]/True Area × 100 [%]) was more striking at smaller diameters (up to –25% in the 2.5 mm tube).Conclusion: Luminal diameters and areas are underestimated by this particular IVUS system. When IVUS imaging and measurements are made during coronary interventions this error should be taken into account with regard to appropriate sizing of the device and the assessment of the postprocedure result. Because systematic errors might also occur in other IVUS systems (not tested in this study), it is advisable to ensure that each system is validated prior to clinical use, especially when exact measurements are required.This paper is followed by an Editorial Comment written by V. Bhargava et al. (see pp. 231–232).     

Atherosclerotic coronary lesions with inadequate compensatory enlargement have smaller plaque and vessel volumes: observations with three dimensional intravascular ultrasound in vivo

Objective—To compare vessel, lumen, and plaque volumes in atherosclerotic coronary lesions with inadequate compensatory enlargement versus lesions with adequate compensatory enlargement.
Design—35 angiographically significant coronary lesions were examined by intravascular ultrasound (IVUS) during motorised transducer pullback. Segments 20 mm in length were analysed using a validated automated three dimensional analysis system. IVUS was used to classify lesions as having inadequate (group I) or adequate (group II) compensatory enlargement.
Results—There was no significant difference in quantitative angiographic measurements and the IVUS minimum lumen cross sectional area between groups I (n = 15) and II (n = 20). In group I, the vessel cross sectional area was 13.3 (3.0) mm² at the lesion site and 14.4 (3.6) mm² at the distal reference (p < 0.01), whereas in group II it was 17.5 (5.6) mm² at the lesion site and 14.0 (6.0) mm² at the distal reference (p < 0.001). Vessel and plaque cross sectional areas were significantly smaller in group I than in group II (13.3 (3.0) v 17.5 (5.6) mm², p < 0.01; and 10.9 (2.8) v 15.2 (4.9) mm², p < 0.005). Similarly, vessel and plaque volume were smaller in group I (291.0 (61.0) v 353.7 (110.0) mm³, and 177.5 (48.4) v 228.0 (92.8) mm³, p < 0.05 for both). Lumen areas and volumes were similar.
Conclusions—In lesions with inadequate compensatory enlargement, both vessel and plaque volume appear to be smaller than in lesions with adequate compensatory enlargement.

     

Additional stenting promotes intimal proliferation and compromises the results of intravascular radiation therapy: an intravascular ultrasound study

Background

Vascular brachytherapy (VBT) reduces in-stent restenosis (ISR). However, additional stenting at the time of radiation may be associated with a worse outcome.

Methods and results

Intravascular ultrasound (IVUS) was performed after VBT and at 6 months follow-up in 79 native artery ISR patients treated with γ-radiation who participated in the Washington Radiation for In-Stent restenosis Trial (WRIST), Gamma-1, and Angiorad Radiation Technology for In-Stent restenosis Trial in Coronaries (ARTISTIC) trials. Patients were treated with ¹⁹²Ir at 14 or 15 Gy at 2 mm from the source. Additional stents were used to treat the ISR lesions in 45 patients; these patients were then compared with the 34 patients treated without restenting. Paired measurements included stent, lumen, and intimal hyperplasia volumes. After the VBT procedure, intimal hyperplasia volume was smaller in the group treated with additional stents (54 ± 33 mm³ vs 34 ± 33 mm³, P = .012), but minimal lumen area was similar between the 2 groups (4.3 ± 1.5 mm² vs 4.7 ± 1.4 mm² respectively, P = NS). Between the time of the VBT procedure and follow-up, intimal hyperplasia volume increased by 27 ± 19 mm³ in the restented group and by 9 ± 21 mm³ in the group treated without additional stents (P = .014). At 6 months, intimal volume was similar in the 2 groups, but minimal lumen area was slightly smaller in the group treated with additional stents (3.4 ± 1.8 mm² vs 4.2 ± 1.7 mm², P = .053). Patients treated with additional stents had more target lesion revascularizations than the group treated without additional stents (38% vs 15%, P = .02).

Conclusions

Additional stenting reduces intimal hyperplasia within the stents acutely. However, it compromises the benefit of VBT by promoting higher intimal regrowth within months after radiation.