Long-term safety of intravascular ultrasound in nontransplant, nonintervened, atherosclerotic coronary arteries

Intravascular ultrasound guidance for lower extremity arterial and venous interventions

This review details the utility of intravascular ultrasound (IVUS) for the management of peripheral artery and venous disease. The purpose of this document is to provide an update in the use of IVUS in peripheral arterial and venous pathology and demonstrate the use of IVUS as a practical diagnostic imaging procedure to evaluate and treat peripheral vascular disorders. IVUS, a diagnostic tool that relies on sound waves to produce precise images of the vessel being evaluated, was originally introduced to the medical community for the purposes of peripheral artery imaging, though it was quickly adapted for coronary interventions with positive outcomes. The utility of IVUS includes vessel measurement, pre- and post-procedural planning, treatment optimisation, and detection of thrombus, dissection or calcium severity. While angiography remains the standard imaging approach during peripheral intervention, multiple observational studies and small prospective trials have shown that in comparison, IVUS provides more accurate imaging detail, which may improve procedural outcomes. IVUS can also address limitations of angiography, including the need to administer contrast medium and eliminate the ambiguity associated with other forms of imaging. This review provides contemporary examples of where IVUS is being used during peripheral intervention as well as representative imaging to serve as a resource for the practising clinician.

A prospective randomized feasibility trial comparing angiography and angiography with intravascular ultrasound for treatment of hemodialysis access failures

OBJECTIVE

Hemodialysis accesses suffer from limited primary patency requiring frequent interventions, revisions, or even abandonment. Prolongation of access life and usability with minimization of these adverse events is paramount. Endovascular methods are established first-line interventions for failing arteriovenous access and treatment of venous outflow stenoses. The Primary goal of this feasibility study was to evaluate intravascular ultrasound (IVUS) during interventional treatments on outcomes in those undergoing angiography for failing hemodialysis access. Secondary goals were to determine differences between IVUS and angiography on vessel and lesion characteristics and impact on treatment.

METHODS

In this prospective, randomized controlled trial, patients scheduled for angiography to evaluate and treat a failing hemodialysis access were randomized to use of angiography (DSA) alone or angiography plus IVUS (DSA + IVUS). Patients were treated by a standardized protocol and seen in follow-up at 2 weeks, and every 3 months for 2 years or until a study endpoint was reached. Measurement of vessel diameters, % stenosis, lesion length, and study endpoints (AV access thrombosis, re-intervention, or surgical revision) were recorded.

RESULTS

A total of 55 subjects were enrolled, 27 in the DSA cohort and 28 in the DSA + IVUS cohort. There were 41 treated lesions in each group. Freedom from the composite endpoint of AV access thrombosis or re-intervention was 46.3% in the DSA cohort and 61.0% in the DSA + IVUS cohort (p = 0.27). Diameter measurements matched between the two imaging modalities only 9 times out of 41 total comparison measures. In pre-treatment lesions with >80% stenosis, IVUS had a greater tendency than DSA to underestimate the severity of stenosis, whereas in pre-treatment lesions with 50-80% stenosis, DSA was more likely than IVUS to underestimate the severity of stenosis. Post-treatment % stenosis had mean difference of -7.5% between DSA versus DSA + IVUS cohorts. In five lesions with <30% stenosis measured by angiogram, IVUS led to treatment escalation.

CONCLUSION

In the interventional treatment of failing angioaccess, IVUS and angiography differ in the vast majority of cases in measurement of vessel diameter. A significant number of patients were found to have suboptimal therapeutic response by IVUS only, which led to an escalation in treatment, and in over one-third of cases, the IVUS results led to a change in treatment plan. The improved patency rates in the IVUS group was not statistically significant in this small population but should be further investigated in a larger trial.

Renal arteriography with endovascular ultrasound for the management of renal infarction patients

Background

Renal infarction (RI) is a rare disease with poor prognosis. Appropriate secondary prevention treatment is essential and requires an exhaustive etiological assessment. We aimed to determine whether invasive endovascular explorations may improve the diagnostic process and change the secondary prevention treatment strategy in RI patients.

Methods

We report a retrospective observational study of 25 RI patients referred to Tours University Hospital between 2011 and 2018 for etiological investigation including renal arteriography and intravascular ultrasonography (IVUS). We sought for antithrombotic treatment regimen, vital status, bleeding and ischemic outcomes during the median follow-up of 59 months.

Results

Invasive explorations showed local arterial disease in 14 patients (56%). This led to a diagnosis or change in diagnosis in 9 patients (36%) and to a change in antithrombotic strategy in 56% of cases, with an increased prescription of antiplatelet therapy. No patient died, only two patients (8%) had persistent mild renal insufficiency. One IVUS complication was reported and treated without any significant long-term consequences.

Conclusion

Invasive endovascular investigations of RI may modify the secondary prevention treatment through a better assessment of the aetiology of RI. Multicentric randomized studies are necessary to advocate the hypothesis that invasive exploration of renal artery can improve long-term prognosis.

Impact of High-Sensitivity Cardiac Troponin Elevation in Relation to Diagnostic Invasive Intravascular Imaging for the Assessment of Coronary Artery Disease

Recent studies reported that cardiac troponin elevation after percutaneous coronary intervention is related to adverse cardiac events. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are often used to assess lesion characteristics in the coronary arteries. However, little is known about the trend of cardiac troponin elevation after diagnostic invasive intracoronary examination and the prognostic influence. We assessed the relationship between myocardial injury manifested by the high-sensitivity cardiac troponin T (hs-cTnT) level after invasive intracoronary examination and future adverse cardiac outcomes. We evaluated 115 patients with stable coronary artery disease who underwent IVUS or OCT for detailed coronary assessment during coronary angiography (CAG). Baseline and post-procedural (within 24 hours after examination) hs-cTnT were measured. In consequence, post-procedural hs-cTnT level and percentage increase were higher in patients with IVUS or OCT during CAG than in those without. Periprocedural myocardial injury (PMI, defined as post-procedural hs-cTnT with upper reference limit greater than five-fold) occurred in 10 (8.6%) patients. There were no significant differences in baseline characteristics between patients with and without PMI, except for left-ventricular diastolic dimension. Only two major adverse cardiac events (MACE, defined as cardiovascular death, nonfatal myocardial infarction, and target lesion revascularization) occurred in non-PMI during a mean observation period of 32 ± 18 months. On Kaplan-Meier analysis, MACE-free survival rate was similar between PMI and non-PMI. In conclusion, a few imperceptible PMI derived by hs-cTnT assay occurred after diagnostic invasive intracoronary examination. However, it was not associated with subsequent poor cardiac outcome.

Visualization of plaque distribution in a curved artery: three-dimensional intravascular ultrasound imaging

Intravascular ultrasound (IVUS) imaging provides an excellent tool for evaluation of the type, morphology, extent, and severity of an atheromatous plaque. 3 D IVUS imaging offers additive information pertaining to morphology of the arterial structures and volumetric plaque distributions. A new 3 D IVUS visualization technique was developed to provide 3 D structural information of a curved artery. A virtual 3 D curved arterial phantom consisting of varying cross-sectional shapes, wall thicknesses, and acoustic intensity information was utilized to validate the nonlinear interpolation technique to create intermediary 2 D IVUS images. IVUS imaging was performed for the iliofemoral arterial segment of an atherosclerotic Yucatan miniswine model. These in-vivo IVUS data were utilized for intermediary IVUS image generation and volumetric 3 D IVUS visualization. Smooth transitional changes of cross-sectional shape, wall thickness and grayscale intensity were found between the intermediary images and the original arterial phantom slices. The 3 D IVUS imaging of the unfolded curved iliofemoral artery provided realistic 3 D luminal surface images of the arteries with physiologic grayscale intensity information. This unique 3 D IVUS imaging technique may help with assessment of 3 D plaque distribution across the curved arterial structure, and improve 3 D visualization of atheromatous components.

Defining the non-vulnerable and vulnerable patients with computed tomography coronary angiography: evaluation of atherosclerotic plaque burden and composition

The shift from coronary plaque stability to plaque instability remains poorly understood despite enormous efforts and expenditures have been assigned to the study of the subject. On the other hand, there have been serious advances in imaging helping us to characterizenon-vulnerable patients The latter has much more value in the clinical decision-making process since it provides high certainty that the patient's probability of a future acute event is low and treatment decisions should be made accordingly. Although coronary plaque rupture is still recognized as the main source of acute thrombotic events, numerous studies have shown that the prediction of events on an individual basis is far more complex and demands a more open approach aimed at characterizing patient risk rather than assessing the risk of thrombosis of a single plaque. Computed tomography coronary angiography (CTCA) has the ability to evaluate non-invasively the extent, burden, severity, and characteristics of coronary artery disease (CAD) and has a close relationship to intravascular ultrasound. On the basis of an excellent negative predictive value with an annualized event rate of ∼0.20% assessed over more than 6000 patients, thus providing a 5-year warranty period, CTCA has been identified as the finest non-invasive tool to exclude CAD. This means that CTCA is able to reliably characterize the non-vulnerable patient. Conversely, in the past few years, several studies have attempted to establish CTCA-derived predictors of acute coronary syndromes, both from a lesion level and a patient level basis with very low positive predictive value, thus questioning the vulnerable patient/plaque concept.

Exploring the natural history of atherosclerosis with intravascular ultrasound

Intravascular ultrasound has emerged as the preferred imaging modality for the characterization of atherosclerotic plaque within the coronary arteries. Ultrasonic imaging reveals the presence of more extensive atheroma than suggested by conventional angiography in patients with coronary artery disease. The ability to precisely quantify atheroma volume in an arterial segment at different time points provides the unique opportunity to investigate the factors that influence the natural history of atheroma progression. Accordingly, serial intravascular ultrasound has been incorporated into a number of clinical trials that have evaluated the impact of medical therapies that modify established risk factors and novel pathological targets. This article will review the increasing role of imaging modalities in the assessment of atherosclerosis and factors that influence its natural history.

A rare case of myocardial infarction related to diagnostic intravascular ultrasound

A 71-year-old man underwent intracoronary stent implantation for acute inferior myocardial infarction (MI). Immediately after diagnostic intravascular ultrasound (IVUS) at 8 months' follow-up, an acute occlusion of the sinus node (SN) artery appeared, which developed sinus arrest with junctional escape rhythm. The serum level of high-sensitivity troponin T (TpT) was markedly elevated on the day after the procedure (2.1-32.5 ng/l), which was indicative of MI related to IVUS. Under continuous intravenous infusion of unfractionated heparin, the escape rhythm changed to lower atrial rhythm on the 4th day, and recovered to sinus rhythm on the 14th day. Coronary angiography (CAG) on 15th day showed a recanalization of the SN artery, but optical coherence tomography identified that disrupted plaque and white thrombus still existed in the ostium of the SN artery. The patient was discharged on maintenance anticoagulation therapy. We hypothesized from this case that IVUS-related myocardial injury may exist without clinical problems. Our retrospective investigation showed that the median levels of high-sensitivity TpT in 20 patients who underwent CAG and subsequent diagnostic IVUS significantly increased from 0.6 (interquartile range 0.3-1.1) to 1.6 (0.7-3.6) ng/l (P < 0.05), suggesting that IVUS may induce very low levels of myocardial injury. In conclusion, we experienced a rare case of IVUS-related MI caused by an acute occlusion of the SN artery. This case reaffirms that we should pay more attention to manipulation of IVUS catheters.

Delineation of atherosclerotic plaque using subharmonic imaging filtering techniques and a commercial intravascular ultrasound system

The ability to delineate atherosclerotic plaque from the surrounding tissue using custom-developed subharmonic imaging (SHI) digital filtering techniques was investigated in vivo using a commercially available system. Atherosclerosis was induced in the aorta of two Watanabe Heritable Hyperlipidemic rabbits following which injections of an ultrasound contrast agent (UCA) Definity (Lantheus Medical Imaging, N Billerica, Massachusetts) were administered. Imaging was performed using a Galaxy intravascular ultrasound (IVUS) scanner (Boston Scientific, Natick, Massachusetts) equipped with an Atlantis® SR Pro Imaging Catheter (Boston Scientific). Four preliminary band-pass filters were designed to isolate the subharmonic signal (from surrounding tissue) and applied to the radio-frequency (RF) data. Preliminary filter performances were compared in terms of vessel-tissue contrast-to-tissue ratio (CTR) and visual examination. Based on preliminary results, a subharmonic adaptive filter and a stopband (SB) filter were designed and applied to the RF data. Images were classified as fundamental, SHI, and SB. Four readers performed qualitative analysis of 168 randomly selected images (across all three imaging modes). The images were scored for overall image quality, image noise, plaque visualization, and vessel lumen visualization. A Wilcoxon signed-rank test was used to compare the scores followed by intraclass correlation (ICC) evaluation. Quantitative analysis was performed by calculating the CTRs for the vessel-to-plaque and vessel-to-tissue (compared using a paired student's t test). Qualitative analysis showed SHI and SB to have significantly less image noise relative to the fundamental mode (p < 0.001). Fundamental mode scored significantly higher than SHI and SB for the remaining three categories. ICC showed mixed results among reader evaluation for delineation of plaque. However, quantitatively, SHI produced the best vessel-plaque CTR.

Safety of embolic protection device-assisted and unprotected intravascular ultrasound in evaluating carotid artery atherosclerotic lesions

BACKGROUND

Significant atherosclerotic stenosis of internal carotid artery (ICA) origin is common (5-10% at ≥ 60 years). Intravascular ultrasound (IVUS) enables high-resolution (120 µm) plaque imaging, and IVUS-elucidated features of the coronary plaque were recently shown to be associated with its symptomatic rupture/thrombosis risk. Safety of the significant carotid plaque IVUS imaging in a large unselected population is unknown.

MATERIAL/METHODS

We prospectively evaluated the safety of embolic protection device (EPD)-assisted vs. unprotected ICA-IVUS in a series of consecutive subjects with ≥ 50% ICA stenosis referred for carotid artery stenting (CAS), including 104 asymptomatic (aS) and 187 symptomatic (S) subjects (age 47-83 y, 187 men). EPD use was optional for IVUS, but mandatory for CAS.

RESULTS

Evaluation was performed of 107 ICAs (36.8%) without EPD and 184 with EPD. Lesions imaged under EPD were overall more severe (peak-systolic velocity 2.97 ± 0.08 vs. 2.20 ± 0.08 m/s, end-diastolic velocity 1.0 ± 0.04 vs. 0.7 ± 0.03 m/s, stenosis severity of 85.7 ± 0.5% vs. 77.7 ± 0.6% by catheter angiography; mean ± SEM; p<0.01 for all comparisons) and more frequently S (50.0% vs. 34.6%, p=0.01). No ICA perforation or dissection, and no major stroke or death occurred. There was no IVUS-triggered cerebral embolization. In the procedures of (i) unprotected IVUS and no CAS, (ii) unprotected IVUS followed by CAS (filters - 39, flow reversal/blockade - 3), (iii) EPD-protected (filters - 135, flow reversal/blockade - 48) IVUS + CAS, TIA occurred in 1.5% vs. 4.8% vs. 2.7%, respectively, and minor stroke in 0% vs. 2.4% vs. 2.1%, respectively. EPD intolerance (on-filter ICA spasm or flow reversal/blockade intolerance) occurred in 9/225 (4.0%). IVUS increased the procedure duration by 7.27 ± 0.19 min.

CONCLUSIONS

Carotid IVUS is safe and, for the less severe lesions in particular, it may not require mandatory EPD use. High-risk lesions can be safely evaluated with IVUS under flow reversal/blockade.

Imaging biomarkers of atherosclerosis

Atherosclerosis imaging plays a significant role in an understanding of the natural history of vascular disease and is increasingly used to assess the efficacy of novel therapeutics. Furthermore, the concepts of 'vulnerable plaque' and, more recently, of 'vulnerable patient' have driven cardiovascular imaging technologies to develop methods for expanded qualitative and quantitative analyses. Indeed, developmental efforts are underway to better demonstrate thin fibrous cap and large necrotic cores, and to determine the correlation between these findings and subsequent cardiovascular events. In this article, we consider a wide variety of cardiovascular imaging techniques that are used as biomarkers of atherosclerosis. These technologies include traditional imaging such as angiography, as well as advanced imaging techniques using both invasive and noninvasive approaches.

Comparison of Plaque Sealing With Paclitaxel-Eluting Stents Versus Medical Therapy for the Treatment of Moderate Nonsignificant Saphenous Vein Graft Lesions

Background— The presence of moderate saphenous vein graft (SVG) lesions is a major predictor of cardiac events late after coronary artery bypass grafting. We determined the effects of sealing moderate nonsignificant SVG lesions with paclitaxel-eluting stents (PES) on the prevention of SVG atherosclerosis progression.

Methods and Results— Patients with at least 1 moderate SVG lesion (30% to 60% diameter stenosis) were randomized either to stenting the moderate SVG lesion with a PES (n=30, PES group) or to medical treatment alone (n=27, medical treatment group). Patients had an angiographic and intravascular ultrasound evaluation of the SVG at baseline and at 12-month follow-up. The primary end points were (1) the ultrasound SVG minimal lumen area at follow-up and (2) the changes in ultrasound atheroma volume in an angiographically nondiseased SVG segment. Mean time from coronary artery bypass grafting was 12±6 years, and mean low-density lipoprotein cholesterol level was 73±31 mg/dL. A total of 70 moderate SVG lesions (39±7% diameter stenosis) were evaluated. Significant disease progression occurred in the medical treatment group at the level of the moderate SVG lesion (decrease in minimal lumen area from 6.3±3.0 to 5.6±3.1 mm 2 ; P <0.001), leading to a severe flow-limiting lesion or SVG occlusion in 22% of the patients compared with none in the PES group ( P =0.014). In the PES group, mean minimal lumen area increased ( P <0.001) from 6.1±2.2 to 8.6±2.9 mm 2 at follow-up ( P =0.001 compared with the medical treatment group at 12 months). There were no cases of restenosis or stent thrombosis. No significant atherosclerosis progression occurred at the nonstented SVG segments. At 12-month follow-up, the cumulative incidence of major adverse cardiac events related to the target SVG was 19% in the medical treatment group versus 3% in the PES group ( P =0.091).

Conclusions— Stenting moderate nonsignificant lesions in old SVGs with PES was associated with a lower rate of SVG disease progression and a trend toward a lower incidence of major adverse cardiac events at 1-year follow-up compared with medical treatment alone, despite very low low-density lipoprotein cholesterol values. This pilot study supports further investigation into the role of plaque sealing in SVGs.

Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT002289835.

Use of vascular ultrasound in clinical trials to evaluate new cardiovascular therapies

Though progress has been made in the fight against cardiovascular disease (CVD), the increasing global prevalence of cardiovascular (CV) risk factors ensures that CVD rates remain high. In order to reduce CVD incidence, a huge effort has been made to uncover additional targets for therapy and novel methods of identifying patients at risk. A low level of high-density-lipoprotein (HDL) cholesterol is recognized as an important independent risk factor for occurrence of a CV event, and new therapies capable of producing effective, clinically relevant increases in this key lipoprotein particle are in development. These therapies will most likely be assessed in comparison with proven CV-risk-reducing therapies such as statin treatment, rather than against a placebo comparator. Inevitably, therefore, clinical end-point trials will increase in both complexity and longevity. Potential efficacy data on new therapies may be revealed sooner by trials using surrogate end points, biomarkers of disease progression known to correlate with clinical events. For novel CV therapies, ultrasound-measured changes in atherosclerosis, such as the change in atheroma burden or plaque volume measured by intravascular ultrasound (IVUS), or ultrasound-measured increase in carotid intima-media thickness (CIMT), may represent useful biomarkers. Both IVUS and CIMT are being widely deployed in trials of new and existing CV therapies to assess their impact on slowing the progression of atherosclerosis, and their use in this regard is the subject of this review.

Role of imaging end points in atherosclerosis trials: focus on intravascular ultrasound

Increasing attention has been focused on the appropriate role of surrogate markers in the development of novel anti-atherosclerotic therapies. Technological advances in imaging modalities allow for visualisation of the entire arterial wall. Intravascular ultrasound (IVUS) has been increasingly employed to precisely quantify the extent of coronary atherosclerosis. Use of IVUS has provided a number of important insights into the natural history of atherosclerosis and the remodelling changes of the arterial wall in response to plaque accumulation. More recently, clinical trials have employed serial evaluations of arterial segments by IVUS to assess the impact of medical therapies.

Intravascular ultrasound in the coronary arteries

With technical improvements in catheter designs, intravascular ultrasound (IVUS) imaging of coronary arteries has become a routine procedure in most cardiac catheterization laboratories. In clinical practice, IVUS imaging of the coronary arteries is commonly performed to answer specific clinical questions such as the evaluation of an indeterminate narrowing of the left main coronary artery. In recent years, IVUS is also being performed as an endpoint for drug treatment trials in the assessment of atherosclerosis progression and/or regression. In this review we will focus on how validation studies of coronary IVUS systems have advanced our ability to use this powerful imaging tool and understand IVUS images, how acoustic and geometric factors affect proposed image processing tools and illustrate some current clinical uses of coronary IVUS.

Comparison of intravascular ultrasound and quantitative coronary angiography for the assessment of coronary artery disease progression

BACKGROUND

The relative merits of quantitative coronary analysis (QCA) and intravascular ultrasound (IVUS) for the assessment of progression/regression in coronary artery disease are uncertain. To explore this subject further, we analyzed the angiographic and IVUS data derived from a contemporary clinical trial population.

METHODS AND RESULTS

We investigated the relationships between QCA and IVUS at single time points (n=525) and also for the changes over time (n=432). QCA and IVUS data underwent central laboratory analyses. Statistically significant correlations were observed between the QCA coronary artery score and the IVUS-derived lumen volume (r=0.65, P<0.0001) and total vessel volume (r=0.55, P<0.0001) and between the QCA cumulative coronary stenosis score and percent atheroma volume on IVUS (r=0.32, P<0.0001) at baseline for matched segments. A similar pattern of correlations was observed for global (all segments) QCA-derived and single-vessel IVUS-derived data. There were statistically significant but weak correlations between the changes over time in lumen dimensions on QCA and IVUS (P=0.005) and between the change in cumulative coronary stenosis score on QCA and percent atheroma volume on IVUS (r=0.14, P=0.01). Nevertheless, patients with and without angiographic progression had changes in plaque volume on IVUS of 9.13 and 0.20 mm3, respectively (P=0.028).

CONCLUSIONS

QCA- and IVUS-derived measures of lumen dimensions are correlated at single time points and for changes over time. Although the change in percent atheroma volume is only weakly correlated with QCA changes as continuous variables, disease progression on QCA is associated with significant increases in plaque volume on IVUS compared with no angiographic progression.

Intravascular ultrasound for the evaluation of therapies targeting coronary atherosclerosis

Many cardiovascular events are clinical manifestations of underlying atherosclerotic disease. The progression of atherosclerosis, traditionally measured by angiography, is predictive of future clinical events and is a valid surrogate marker of cardiovascular (CV) disease. There is growing interest in using novel surrogate end points in clinical trials to expedite the development of new CV therapies. Innovative imaging technologies, such as intravascular ultrasound (IVUS), may carry advantages for the evaluation of coronary atherosclerotic burden and disease progression. Unlike angiography, which displays only the opacified luminal "silhouette," IVUS provides transmural imaging of the entire arterial wall and permits both detection of early-stage atherosclerosis and accurate cross-sectional and even 3-dimensional quantification of plaques. Intravascular ultrasound is now used to guide therapeutic interventions and for diagnostic purposes, primarily for the evaluation of ambiguous lesions and left main coronary artery disease. In addition, clinical studies are using IVUS serially to measure plaque progression, which appears to be related to future CV events. Although the probative force of clinical end point studies still is stronger, IVUS is catching up. Currently, several trials of CV therapies use IVUS-determined plaque progression as the end point. The rationale for using IVUS-based surrogate end points in clinical trials is discussed in the present review. Key advantages of using IVUS-based surrogate end points versus clinical outcome include smaller patient numbers and substantially shorter trial durations; this reduces costs and may expedite the development and testing of new drugs. We expect in the near future a further increase of the use of IVUS-based surrogate end points in trials that evaluate novel CV therapies targeting on coronary atherosclerosis.

Application of intravascular ultrasound in anti-atherosclerotic drug development

The background use of a number of established therapies presents a key challenge for the development of novel anti-atherosclerotic agents: how to predict potential efficacy before the completion of long-term trials with endpoints such as mortality. This challenge has stimulated the search to develop intermediate measures of efficacy. Recent advances now allow intravascular ultrasound (IVUS) to provide an accurate assessment of atheroma accumulation within the arterial wall. Here we describe how IVUS can be applied to the serial assessment of atheroma burden in response to treatment with a range of anti-atherosclerotic strategies, which has resulted in its emergence as a key technology in the evaluation and approval of novel drugs.

Reproducibility of intravascular ultrasound radiofrequency data analysis: implications for the design of longitudinal studies

OBJECTIVES

The purpose of this study was to assess in vivo the reproducibility of tissue characterization using spectral analysis of intravascular ultrasound (IVUS) radiofrequency data (IVUS-VH).

BACKGROUND

Despite the need for reproducibility data to design longitudinal studies, such information remains unexplored.

METHODS AND RESULTS

IVUS-VH (Volcano Corp., Rancho Cordova, USA) was performed in patients referred for elective percutaneous intervention and in whom a non-intervened vessel was judged suitable for a safe IVUS interrogation. The IVUS catheters used were commercially available catheters (20 MHz, Volcano Corp., Rancho Cordova, USA). Following IVUS-VH acquisition, and after the disengagement and re-engagement of the guiding catheter, an additional acquisition was performed using a new IVUS catheter. Fifteen patients with 16 non-significant lesions were assessed by 2 independent observers. The relative inter-catheter differences regarding geometrical measurements were negligible for both observers. The inter-catheter relative difference in plaque cross-sectional area (CSA) was 3.2% for observer 1 and 0.5% for observer 2. The limits of agreement for (observer 1 measurements) lumen, vessel, plaque and plaque burden measurements were 0.82, -1.10 mm(2); 0.80, -0.66 mm(2); 1.08, -0.66 mm(2); and 5.83, -3.89%; respectively. Limits of agreement for calcium, fibrous, fibrolipidic and necrotic core CSA measurements were 0.22, -0.25 mm(2); 1.02, -0.71 mm(2); 0.61, -0.65 mm(2); and 0.43, -0.38 mm(2) respectively. Regarding the inter-observer agreement, the limits of agreement for lumen, vessel, plaque and plaque burden measurements were 2.61, -2.09 mm(2); 2.20-3.03 mm(2); 1.70, -3.04 mm(2); and 9.16, -16.41%; respectively, and for calcium, fibrous, fibrolipidic and necrotic core measurements of 0.08, -0.09 mm(2); 0.89, -1.28 mm(2); 0.74, -1.06 mm(2); and 0.16, -0.20 mm(2); respectively.

CONCLUSIONS

The present study demonstrates that the geometrical and compositional output of IVUS-VH is acceptably reproducible.