Intracoronary two-dimensional ultrasound imaging in the assessment of plaque morphologic features and the planning of coronary interventions

Impact of plaque and luminal morphology in balloon angioplasty of the femoropopliteal artery: an intravascular ultrasound analysis

Objective

To assess the effect of plaque and luminal morphologies in balloon angioplasty of femoropopliteal lesions using intravascular ultrasound (IVUS).

Methods

This retrospective, observational study analyzed 836 cross-sectional images using IVUS, from 35 femoropopliteal arteries of patients who underwent endovascular treatment between September 2020 and February 2022. Pre- and post-balloon angioplasty images were matched per 5 mm. Post-balloon angioplasty images were grouped into successful (n = 345) and unsuccessful (n = 491) groups. Plaque and luminal morphologies (such as severity of calcification, vascular remodeling, and plaque eccentricity) were extracted before the balloon angioplasty procedure to identify the predictors of unsuccessful balloon angioplasty. Additionally, 103 images with severe dissection were analyzed using IVUS and angiography.

Results

In univariate analyses, the predictive factors for unsuccessful balloon angioplasty were vascular remodeling (p < .001), plaque burden (p < .001), lumen eccentricity (p < .001), and balloon/vessel ratio (p = .01). Predictive factors for severe dissections were the guidewire route (p < .001) and balloon/vessel ratio (p = .04). In multivariate analysis, the predictive factors for unsuccessful balloon angioplasty included lumen eccentricity (odds ratio [OR]: 3.99, 95% confidence interval [CI]: 1.28-12.68, p = .02) and plaque burden (OR: 1.03, 95% CI: 1.02-1.04; p < .001). For severe dissections, the independent risk factor was an eccentric guidewire route (OR: 2.10, 95% CI: 1.22-3.65, p = .01).

Conclusion

High plaque burden and luminal eccentricity were risk factors for failed femoropopliteal artery balloon angioplasty. Additionally, eccentric guidewire routes predicted severe dissection.

Clinical Outcomes and Prevalence of Intravascular Ultrasound Use at a Tertiary Care Hospital in a South Asian Country

Objectives:

Intravascular ultrasound (IVUS) plays a pivotal role in the current era of coronary interventions. We aimed to determine the prevalence of IVUS use and clinical outcomes of IVUS-guided percutaneous treatment of coronary arteries lesions in a South Asian country.

Material and Methods:

It is a retrospective observational study, a total of 134 consecutive patients having done IVUS, was enrolled from January 2013 to March 2020 at a single center.

Results:

Out of 134 patients, 97 (72.4%) were male with a mean age of 63.1 ± 12.9 years. The prevalence of IVUS in our center was 3.0%. The most frequent comorbidity observed was dyslipidemia, n = 111 (82.8%). Non-ST-elevation myocardial infarction, n = 50 (37.3%), was the common mode of presentation. On coronary angiogram, the left main (LM) disease was found in n = 46 (34.3%), however, single-vessel disease, n = 51 (38.1%), was most commonly noted. IVUS utilization was higher in the left anterior descending, n = 94 (70.1%), followed by LM, n = 46 (34.3%). The LM mean minimal luminal area was 6.0 ± 2.6 mm² and minimal luminal diameter was 4.53 mm ± 0.6 (mean). The coronary artery dissection was noted in n = 15 (11.2%). The mean duration of follow-up in our study was 40.3 ± 30.1 months. Major adverse cardiac events (MACEs) were recorded in n = 13 (9.7%), which included heart failure, n = 4 (3%). Cardiovascular death and target vessel revascularization occurred in n = 3 (2.2%).

Conclusion:

IVUS results in a significant decrease in MACE. Our data might support the broader use of IVUS in both developed and in our part of the world.

Comparison of Two Different Strategies of Intravascular Ultrasound Guidance during Percutaneous Coronary Intervention; Routine versus Selective

BACKGROUND AND OBJECTIVES

Intravascular ultrasound (IVUS) is helpful during percutaneous coronary intervention (PCI), because it can be used to confirm good apposition or optimal expansion of stents. In this study, we compared angiographic result as well as clinical outcomes between two different strategies of IVUS-guidance, the selective vs. the routine.

SUBJECTS AND METHODS

The study population consisted of 279 patients undergoing electric and emergency intracoronary implatation of TAXUS stent from August 2003 through September 2006. For this study, we divided physicians into two groups; doctors to perform PCI under 'routine' IVUS-guidance vs. PCI under 'selective' IVUS-guidance. Among a total of 279 patients (384 lesions) who underwent PCI with TAXUS stent, 87 patients underwent the procedure under the strategy of 'routine' IVUS-guidance, whereas 192 patients under 'selective' IVUS-guidance.

RESULTS

The baseline clinical features of the patients are similar between the two groups. The actual rate of IVUS usage was 89.2% in the routine group and 68.2% in the selective group (p<0.01). A high rate of adjunctive ballooning was determined as a remarkable procedure-related parameter which was comparable between the two groups (72.5% vs. 76.1% in routine vs. selective, p=0.57). The minimal lumen diameter at immediate post-PCI was significantly larger in the routine IVUS group than that in the selective group (2.58 mm vs. 2.48 mm, p=0.03). However, the difference disappeared during the follow-up period (1.98 mm vs. 1.98 mm, p=0.94). Clinical outcomes at 1 year were not different between the two groups.

CONCLUSION

PCI under the strategy of 'selective' IVUS-guidance was comparable to PCI under 'routine' IVUS-guidance in terms of angiographic and clinical outcomes in circumstances with frequent use of adjunctive ballooning after stenting.

Continued improvement of clinical outcome and cost effectiveness following intravascular ultrasound guided PCI: insights from a prospective, randomised study

OBJECTIVE

To investigate in a prospective randomised study both long term clinical effects and cost effectiveness of percutaneous coronary interventions (PCI) with or without intravascular ultrasound (IVUS) guidance.

METHODS

108 male patients with stable angina referred for PCI of a significant coronary lesion were randomly assigned to IVUS guided PCI or conventional PCI. Individual accumulated costs of the entire follow up period were calculated and compared in the randomisation groups. Effectiveness of treatment was measured by freedom from major adverse cardiac events.

RESULTS

Cost effectiveness of IVUS guided PCI that was noted at six months was maintained and even accentuated at long term follow up (median 2.5 years). The cumulated cost level was found to be lower for the IVUS guided group, with a cumulated cost of &163 672 in the IVUS guided group versus &313 706 in the coronary angiography group (p = 0.01). Throughout the study, mean cost per day was lower in the IVUS guided PCI group (&2.7 v & 5.2; p = 0.01). In the IVUS group, 78% were free from major adverse cardiac events versus 59% in the coronary angiography group (p = 0.04) with an odds ratio of 2.5 in favour of IVUS guidance.

CONCLUSION

IVUS guidance results in continued improvement of long term clinical outcome and cost effectiveness. The results of this study suggest that IVUS guidance may be used more liberally in PCI.

Reproducibility of intravascular ultrasound and intracoronary Doppler measurements

The aim of this study was to evaluate the reproducibility of intravascular ultrasound (IVUS) and intracoronary (IC) Doppler flow velocity measurements. The use of IVUS and IC Doppler has been suggested as a means for percutaneous coronary intervention (PCI) guidance in a series of studies. This would require an acceptable level of accuracy and reproducibility of these two methods for lesion evaluation. In this study, the main focus was on the issue of reproducibility. One hundred and eight patients referred for PCI entered into the study. Inter- and intraobserver variability was measured. Catheter difference was assessed. On-line and off-line measurements were compared. MUSIC criteria were assessed off-line, twice. Calculated and measured diameters were compared. After having obtained initial IC Doppler measurements, the Doppler wire was immediately withdrawn and repositioned for reacquisition of Doppler measurements. IVUS measurements are reproducible and reliable off-line and, to a slightly lesser degree, on-line. Area measurements should be performed more than once and the mean used for vessel description. Lumen diameters should be calculated from the mean of the area measurements. A measuring technique consensus should be reached and adhered to. CFR measurements can be used to determine reduced vs. normal flow reserve. In this study, it was found that proximal to distal velocity ratio and diastolic to systolic velocity ratio variability made these parameters unsuitable for PCI guidance.

Restenosis and clinical outcome in patients treated with amlodipine after angioplasty: results from the Coronary AngioPlasty Amlodipine REStenosis Study (CAPARES)

OBJECTIVES

Our intent was to investigate the effect of the dihydropyridine calcium channel blocker amlodipine on restenosis and clinical outcome in patients undergoing percutaneous transluminal coronary angioplasty (PTCA).

BACKGROUND

Amlodipine has sustained vasodilatory effects and relieves coronary spasm, which may reduce luminal loss and clinical complications after PTCA.

METHODS

In a prospective, double-blind design, 635 patients were randomized to 10 mg of amlodipine or placebo. Pretreatment with the study drug started two weeks before PTCA and continued until four months after PTCA. The primary angiographic end point was loss in minimal lumen diameter (MLD) from post-PTCA to follow-up, as assessed by quantitative coronary angiography (QCA). Clinical end points were death, myocardial infarction, coronary artery bypass graft surgery and repeat PTCA (major adverse clinical events).

RESULTS

Angioplasty was performed in 585 patients (92.1%); 91 patients (15.6%) had coronary stents implanted. Follow-up angiography suitable for QCA analysis was done in 236 patients in the amlodipine group and 215 patients in the placebo group (per-protocol group). The mean loss in MLD was 0.30 +/- 0.45 mm in the amlodipine group versus 0.29 +/- 0.49 mm in the placebo group (p = 0.84). The need for repeat PTCA was significantly lower in the amlodipine versus the placebo group (10 [3.1%] vs. 23 patients [7.3%], p = 0.02, relative risk ratio [RR]: 0.45, 95% confidence interval [CI]: 0.22 to 0.91), and the composite incidence of clinical events (30 [9.4%] vs. 46 patients (14.5%), p = 0.049, RR: 0.65, CI: 0.43 to 0.99) within the four months follow-up period (intention-to-treat analysis).

CONCLUSIONS

Amlodipine therapy starting two weeks before PTCA did not reduce luminal loss, but the incidence of repeat PTCA and the composite major adverse clinical events were significantly reduced during the four-month follow-up period after PTCA with amlodipine as compared with placebo.

Value of Lesion Morphology and of Residual Stenosis in Predicting Late Clinical Outcomes and Restenosis Rate Post-PTCA in Single-Vessel Disease

The study assessed an impact of stenosis morphology before coronary angioplasty (PTCA) and of residual diameter stenosis after the procedure on major adverse cardiac events and restenosis rate at 1 year after intervention in single-vessel disease. Visual analysis of stenoses, using the ABC lesion score system and on-line quantitative evaluation (ACA, DCI, Philips), was performed in 70 patients undergoing PTCA. Recurrence of angina at rest and/or positive treadmill exercise test (TET) >/=6 weeks after PTCA and/or major cardiac events were considered as evidence of restenosis. At 1 year follow-up 56 patients (80%) were event free, without angina at rest and without positive TET, with residual diameter (RD) after PTCA a mean of 2.00 +/- 0.48 mm. In the restenosis group (n = 14) RD was a mean of 1.58 +/- 0.43 mm (p < 0.01): there were three patients with angina at rest, five with Positive TET, and six with cardiac events. In this group, one-half of the stenoses was in class C of the lesion. Residual diameter stenosis, measured objectively after balloon angioplasty, and evaluation of lesion morphology before PTCA can predict late clinical outcomes after the procedure in single-vessel disease.

Impact of target lesion calcification on coronary stent expansion after rotational atherectomy

BACKGROUND

Calcified lesions carry the risk of suboptimal stent expansion. The purpose of this study was to investigate the impact of target lesion calcification on intracoronary ultrasound (ICUS) guided stent expansion after rotational atherectomy.

METHODS

Stent expansion was assessed by ICUS in 39 patients with the aid of the proximal stent/proximal reference lumen, the minimal stent/mean reference lumen, and the minimal stent/minor reference lumen ratios as well as the symmetry index. Thirty-nine stent implantations in uncalcified lesions served for comparison.

RESULTS

Relative stent expansion ranged between 76.3% +/- 6.7% and 98.4% +/- 16.4%. Categorization according to an ICUS-derived arc of superficial lesion calcium of <180 degrees (average 102 +/- 74 degrees) or >180 degrees (average 248 +/- 71 degrees) revealed decreased stent symmetry in calcified lesions >180 degrees compared with the control group (P <.05). Despite a trend toward less expansion with increasing calcium load, no significant differences of the lumen area ratios between the study groups was present.

CONCLUSION

Rotational atherectomy before ICUS-guided stent implantation enables adequate stent expansion even in significant superficial target lesion calcification.

Intravascular ultrasound evaluation of plaque distribution at curved coronary segments

Although the distribution of atherosclerosis at the curved coronary segments has implications for atherogenesis and interventional procedures, few data exist regarding the plaque distribution in these sites. Therefore, we prospectively analyzed the intravascular ultrasound images of 55 coronary sites from 37 patients where the atherosclerotic plaque and pericardium were simultaneously demonstrated by intravascular ultrasound. The pericardial images were defined as a high-intensity linear echo image moving during cardiac cycles outside the vessel wall. By the line that was parallel to the pericardial image, the vessel area was divided into 2 semicircles with the same area, namely myocardial and pericardial sides. In each side, the maximal thickness, area, and percent area of plaque were measured. The plaque thickness and area of the myocardial side were significantly greater (1.5 +/- 0.5 mm, 4.9 +/- 2.1 mm or 66%, mean +/- SD) than those of the pericardial side (1.1 +/- 0.4 mm, 3.5 +/- 2.1 mm2 or 45%, p < 0.01). The maximal plaque thickness was positioned at the point with a mean angle of 139 +/- 37 degrees from the point just facing the pericardial image, indicating that atherosclerosis was eccentrically located on the opposite side of the pericardium in these coronary segments, and suggesting that the side of the pericardial image represents the outer curvature of the coronary artery. These results indicate that the pericardial images can be seen by intravascular ultrasound, facilitating the recognition of the disease distribution in situ. The eccentric plaque located on the inner wall at the curved coronary segments, probably due to uneven local shear stress, may have implications for the interventional procedures for these segments.

Intravascular ultrasound and balloon percutaneous transluminal coronary angioplasty

Intracoronary ultrasound provides unique information during percutaneous transluminal coronary angioplasty (PTCA), including more accurate measurement of vessel size and plaque burden as well as plaque characteristics such as composition and distribution. As a research tool, it has been useful in determining the mechanisms of PTCA, which primarily involves vessel stretch, plaque fracture/dissection, and plaque redistribution. It may be clinically useful in assessing lesion severity in patients with indeterminate clinical and angiographic findings. Plaque characteristics as determined by intracoronary ultrasound may also be helpful in developing an individualized interventional approach for each lesion. Finally, certain intracoronary ultrasound findings after PTCA, such as large dissections and large residual stenosis, are associated with increased risk of short-term and long-term adverse outcomes.

Intravascular ultrasound in the setting of directional coronary atherectomy and percutaneous transluminal coronary rotational atherectomy

The first section of this article reviews how intracoronary ultrasound (ICUS) has been used to identify the mechanisms of action of directional coronary atherectomy (DCA) and examines the influence of plaque composition and morphology on DCA outcomes. The process of restenosis is then described. Results from trial using ICUS-guided DCA are evaluated, demonstrating how the information obtained from ICUS is being used to improve the angiographic and clinical outcomes of directional atherectomy. Finally, data are incorporated to provide practical applications for the use of DCA.

High-frequency ultrasonic detection of thrombi with a targeted contrast system

Site-targeted acoustic contrast agents used in conjunction with high-frequency intravascular ultrasound have the potential to localize and characterize intravascular pathology. The present study quantifies the utility of a novel, site-targeted ultrasonic contrast agent with high-frequency ultrasound (30 to 50 MHz) and demonstrates the feasibility of the new agent for augmenting detection of targeted pathology with intravascular ultrasonic catheters. High-frequency acoustic microscopy was used to image avidinconjugated nitrocellulose membranes after exposure to a control or biotinylated contrast agent. Increases (p < 0.05) in backscattered power of approximately 66 dB (4-fold) were found for the biotinylated, but not the control contrast agent. Intravascular ultrasonic images (30 MHz nominal center frequency) of plasma clots after exposure to the targeted contrast agent were brighter (p < 0.05) than in controls. These results demonstrate high-frequency acoustic enhancement with a novel targeted contrast agent and may extend the potential diagnostic spectrum of intravascular ultrasound.

Impact of plaque morphology and composition on the mechanisms of lumen enlargement using intracoronary ultrasound and quantitative angiography after balloon angioplasty

Limited information is provided by angiography on plaque morphology and composition before balloon angioplasty. Identification of plaques associated with reduced lumen gain or a high complication rate may provide the rationale for using alternative revascularization devices. We studied 60 patients with quantitative angiography and intracoronary ultrasound (ICUS) before and after balloon dilation. Angiography was used to measure transient wall stretch and elastic recoil. ICUS was used to investigate the mechanisms of lumen enlargement among different plaque compositions and in the presence of a disease-free wall (minimal thickness < or = 0.6 mm). Compared with ultrasound, angiography underestimated the presence of vessel calcification (13% vs 78%), lumen eccentricity (35% vs 62%), and wall dissection (32% vs 57%). ICUS measurements showed that balloon angioplasty increased lumen area from 1.82 +/- 0.51 to 4.81 +/- 1.43 mm2. Lumen enlargement was the result of the combined effect of an increase in the total cross-sectional area of the vessel (wall stretching, 43%) and of a reduction in the area occupied by the plaque (plaque compression or redistribution, 57%). Vessels with a disease-free wall had smaller lumen gain than other types of vessels (2.13 +/- 1.26 vs 3.59 +/- mm2, respectively, p < 0.01). Wall stretching was the most important mechanism of lumen enlargement in vessels with a disease-free wall (79% vs 37% in the other vessels). Angiography revealed a direct correlation between temporary stretch and elastic recoil that was responsible for 26% of the loss of the potential lumen gain. Thus, lumen enlargement after balloon angioplasty is the combined result of wall stretch and plaque compression or redistribution. ICUS indicates that vessels with a remnant arc of disease-free wall are dilated mainly by wall stretching compared with other types of vessels and are associated with a smaller lumen gain.