Endovascular treatment of infrarenal aortic stenosis: importance of multimodality imaging.

We sought to describe the evolution in imaging and interventional options for endovascular treatment of significant infrarenal aortic stenosis. Balloon angioplasty and stent implantation for infrarenal aortic stenosis has generally required large-sized arterial access sheaths in the past, and was typically guided by visual size assessment. Computerized tomography angiography enables accurate preprocedural assessment of severity and extent of aortic atherosclerosis, degree of calcification, and luminal dimensions at both stenosis and reference sites, and visualizes possible aneurysm. Intraprocedural pressure gradient measurements evaluate the hemodynamic response to revascularization. On the other hand, intravascular ultrasound can further verify accuracy of equipment sizing. Small-profile stents and balloons can be used via small-sized sheaths, thereby rendering the procedure possible in patients with extensive peripheral arterial disease or small iliofemoral arteries. Improved non-invasive and intravascular imaging can guide with great accuracy infrarenal aortic stenosis procedures and may enable the use of reduced-size access sheaths and devices in fragile patients with vasculopathies.

Intravascular ultrasound findings of stent fractures in patients with Sirolimus- and Paclitaxel-eluting stents.

We compared intravascular ultrasound (IVUS) findings of fractures of sirolimus-eluting stents (SESs) versus paclitaxel-eluting stents (PESs). IVUS findings in 6 PES fractures (all in the right coronary artery) in 6 patients from a clinical trial cohort were compared to 14 SES fractures (8 in the right coronary artery, 2 in the left anterior descending coronary artery, and 4 in the left circumflex coronary artery) in 13 patients from our institutional cohort. Comparing PES fractures to SES fractures, IVUS analysis showed (1) similar frequency of complete stent fracture (1 of 6, 17%, vs 3 of 14, 21%, p >0.99), (2) similar frequency of fracture adjacent to calcified plaque or stent metal overlap (5 of 6, 86%, vs 14 of 14, 100%, p = 0.99), (3) more frequent complete malalignment of proximal and distal fragments in PES strut fractures compared to SES fractures (5 of 6, 83%, vs 1 of 14, 7%, p = 0.002), (4) similar stent lengths (45.2 mm, 23.8 to 50.7, vs 39.3 mm, 22.6 to 73.4, p >0.99), (5) similar fracture lengths (0.5 mm, 0.4 to 0.7, vs 0.7 mm, 0.6 to 1.0, p = 0.14), and (6) larger reference external elastic membrane area (15.0 mm(2), 13.5 to 18.0, vs 10.4 mm(2), 6.8 to 13.6, p = 0.01). In conclusion, malalignment of proximal and distal stent fragments more often occurred in PES fractures compared to SES fractures; otherwise the IVUS features of PES and SES fractures were similar.

Intravascular ultrasound assessment of cobalt chromium versus stainless steel drug-eluting stent expansion.

It is not clear whether the thin struts and different alloy of a cobalt chromium stent will cause greater acute stent recoil compared to conventional stainless steel stents. We used postintervention intravascular ultrasound (IVUS) examinations to study 99 patients with 116 stented lesions: 61 Xience/Promus stents (cobalt chromium stent group) and 27 Taxus Liberté and 28 Cypher stents (stainless steel stent group). The IVUS images were obtained before and immediately after stent implantation with only the stent-delivery balloon. The ratio of the IVUS-measured to manufacturer-predicted stent diameter and area was the measure of acute stent recoil and expansion. The baseline patient characteristics, lesion morphology, and procedural details were comparable between the 2 groups. The ratio of the IVUS-measured to manufacturer-predicted stent diameter and area was 0.74 versus 0.73 (p = 0.57) and 0.63 versus 0.63 (p = 0.69), respectively, for the cobalt chromium and stainless steel stents. In conclusion, the acute performance of Xience/Promus was similar to that of previous stainless steel stents, and the thinner cobalt chromium metallic platform did not compromise the radial strength of the stent.

Is accurate intravascular ultrasound evaluation of the left circumflex ostium from a left anterior descending to left main pullback possible?

Treatment of left main coronary artery bifurcation lesions might depend on the ostial left circumflex (LC) or ostial left anterior descending (LAD) disease severity. We sought to evaluate whether intravascular ultrasound assessment of the side branch ostium requires direct imaging or is accurate from the main vessel. Our retrospective analysis included 126 patients with left main coronary artery bifurcation disease (plaque burden > or =40% by intravascular ultrasound scanning). We analyzed pullbacks from the LAD and the LC. First, during the main vessel pullback (ie, from the LAD), we evaluated the side branch ostium (ie, of the LC). Second, we compared this oblique view with the direct ostial measurements during LC pullback. Finally, we repeated this process, imaging the ostial LAD from the LC. From the LAD, the oblique LC ostial lumen diameter was 3.0 +/- 0.8 mm compared to the directly measured lumen diameter of 2.9 +/- 0.6 mm. From the LC, the oblique LAD ostial lumen diameter was 2.9 +/- 1.1 mm compared to the directly measured lumen diameter of 2.8 +/- 0.5 mm. However, Bland-Altman plots showed significant variation in the oblique versus direct comparisons. The 95% limits of agreement ranged from -1.84 to 1.14 mm (mean difference -0.35, SD 0.75) for the LAD and -1.69 to 1.22 mm (mean difference -0.23, SD 0.73) for the LC. The "oblique view" detection of any plaque in the side branch predicted 40% or 70% plaque burden with good sensitivity but poor specificity. In conclusion, intravascular ultrasound evaluation of a side branch ostium from the main vessel is only moderately reliable, especially for distal left main coronary artery lesions. For an accurate assessment of the side branch ostium, direct imaging is necessary.

Impact of myocardial bridge on clinical outcome after coronary stent placement.

Most intravascular ultrasound (IVUS)-identifiable myocardial bridges (MBs) were not appreciated angiographically, especially when they occurred adjacent to fixed proximal obstructive disease. The impact of MB stent placement on clinical outcome was determined in 317 consecutive patients with obstructive left anterior descending coronary artery lesions undergoing coronary stent placement. In these patients, IVUS identified 70 MBs, defined as a segment of coronary artery with both systolic compression and perivascular echolucent muscle. IVUS showed that the stent extended into the MB segment beyond the obstructive lesion in 24 patients (34%; MB stent group), although significant plaque was not observed within any MB segment. In the remaining 46 patients, the left anterior descending artery stent was implanted in only the obstructive lesion, avoiding the distal MB segment (non-MB stent group). Minimum stent area was significantly smaller in the MB stent group than non-MB stent group (4.8 +/- 1.1 vs 5.8 +/- 1.8 mm(2); p = 0.02). Rates of target-lesion revascularization, target-vessel revascularization, and composite end point (death/myocardial infarction/target-lesion revascularization/target-vessel revascularization, evaluated at a mean follow-up of 358 +/- 252 days) were more common in patients with versus without MB stent placement. Specifically, target-lesion revascularization rates were 24% versus 3%, respectively (log-rank p = 0.003). In-stent restenosis occurred within the stented MB segment in 3 of 5 MB stent group patients who required target-lesion revascularization (60%). In conclusion, inadvertent MB stent placement in left anterior descending artery lesions occurred commonly and may have been associated with an increased incidence of late events.

Impact of gender and age on in vivo virtual histology-intravascular ultrasound imaging plaque characterization (from the global Virtual Histology Intravascular Ultrasound [VH-IVUS] registry).

Virtual histology intravascular ultrasound (VH-IVUS) analyses were performed in the first 990 patients enrolled in the 3,000+ patient global VH-IVUS Registry to assess the impact of gender and age on in vivo VH-IVUS plaque characterization. The 990 patients were divided into 3 age group terciles (<58, 58 to 68, and >68 years) and again divided according to gender. In conclusion, (1) both women and men had an increase in plaque with increasing age; (2) at any age, men had more plaque than women; (3) percentages of dense calcium and necrotic core increased with increasing patient age in both men and women; and (4) gender differences were lowest in the oldest tercile (>68 years).

Classification and potential mechanisms of intravascular ultrasound patterns of stent fracture.

We sought to examine the intravascular ultrasound (IVUS) findings of stent fracture. Stent fracture has been implicated as a cause of drug-eluting stent failure. IVUS is more likely to identify mechanisms of stent failure -- including stent fracture -- than angiography. Twenty stent fractures diagnosed by IVUS in 17 patients were evaluated. Eighteen stent fractures (90%) occurred in sirolimus-eluting Cypher stents, and 2 stent fractures (10%) occurred in bare metal stents, but none occurred in paclitaxel-eluting Taxus stents. Half of the stent fractures presented < or =1 year after implantation, and (1/2) presented >1 year after implantation. IVUS analysis showed that 9 stent fractures were complete (45%) and 11 were partial (55%); 10 (50%) were adjacent to stent metal overlap; and 5 occurred in a coronary aneurysm accompanied by malapposition (all Cypher stents) despite the absence of an aneurysm at index stenting. Compared with 60 matched control segments in patients without stent fracture, but with similar clinical events, the stent fracture group had longer stent segments (45.2 +/- 23.0 vs 28.5 +/- 14.9 mm, p = 0.003). Comparing stent fractures associated with an aneurysm (n = 5) with those that did not occur in association with an aneurysm (n = 15) showed that complete stent fracture was more frequent (100% vs 27%, p = 0.008), and all presented >1 year after index stenting (vs 33%, p = 0.03). In conclusion, IVUS is helpful to identify stent fracture as a cause of stent failure and to understand possible mechanisms of stent fracture such as aneurysm formation.

The axial distribution of lesion-site atherosclerotic plaque components: an in vivo volumetric intravascular ultrasound radio-frequency analysis of lumen stenosis, necrotic core and vessel remodeling.

Radio-frequency intravascular ultrasound (IVUS) analysis characterizes atherosclerotic plaques into necrotic core (NC), dense calcium (DC), fibrofatty (FF) and fibrotic (FI) tissue. We studied axial plaque component distribution with respect to stenosis and remodeling. Preintervention virtual histology (VH) IVUS was performed in 81 pts (90 de novo lesions: 43 left anterior descending artery [LAD] and 47 right coronary artery [RCA]). VH-IVUS at the reference, minimum lumen area (MLA) and maximum NC (MaxNC) sites were analyzed. Pullback length of 31.1 +/- 12.0 mm spanned a lesion length of 13.8 +/- 9.5 mm. The MaxNC site was located at the MLA in 3.3% of lesions, proximal to the MLA in 61% of lesions (by 4.11 mm) and distal to the MLA in 35.6% of lesions (by 3.56 mm). The %DC was greater at the MaxNC and %FI and %FF plaque were less than at the MLA site. Lesion fiberoatheromas (FAs) were more often detected at the MaxNC than the MLA (96% versus 51%) and were more often classified as thin-caped or multilayered than the MLA sites. The remodeling index was larger at the MaxNC than MLA sites and correlated with the NC area both at the MLA (r(2) 0.068, p = 0.013) and at the MaxNC (r(2) 0.074, p = 0.009). In conclusion, grey-scale and VH-IVUS analysis showed that the MLA is rarely at the site of greatest instability (largest NC and remodeling) and necrotic core on VH is correlated with remodeling index. These in vivo findings are consistent with previously reported histopathologic data and have important implications for the detection and treatment of coronary artery disease.

Comparison of angiographic and intravascular ultrasonic detection of myocardial bridging of the left anterior descending coronary artery.

The purpose of this study was to determine the incidence, location, and clinical features of myocardial bridging (MB) detected by intravascular ultrasound (IVUS) and to compare IVUS-detectable versus angiographically detectable MBs. IVUS images were analyzed in 331 consecutive patients with de novo coronary lesions located in the left anterior descending coronary artery (LAD). MB was defined as a segment of coronary artery having systolic compression and echocardiographically lucent muscle surrounding the artery (IVUS) or systolic milking (angiography). Although angiography detected MB in only 3% of patients (11 of 331), 75 MB segments (23%, 75 of 331, p <0.001) were identified by IVUS. Maximum plaque burden within the MB segment measured only 25 +/- 7%, and abnormal intimal thickness (defined as >or=0.5 mm) was not observed within the bridged segment of any patient with MB, although the study population had advanced atherosclerosis. Vessel and lumen areas in the MB segment were significantly smaller than those in adjacent proximal and even distal reference segments. Angiographically detectable MB was significantly longer, located more proximally in the LAD, and had more severe systolic compression by IVUS. Angiographically silent MB more often occurred in the presence of an adjacent proximal stenosis and lower left ventricular ejection fraction. In conclusion, IVUS may provide useful anatomic information for the accurate diagnosis of MBs that are largely angiographically silent. IVUS-detectable MBs were observed in approximately 1/4 of patients undergoing LAD imaging at our center.

In vivo virtual histology intravascular ultrasound correlates of risk factors for sudden coronary death in men: results from the prospective, multi-centre virtual histology intravascular ultrasound registry.

AIMS: We hypothesized a relationship between virtual histology intravascular ultrasound (VH-IVUS) findings and risk factors histopathologically associated with sudden coronary death (SCD) in men: cigarette smoking and an increased total cholesterol-to-high-density lipoprotein cholesterol (HDL-C) ratio (TC/HDL > 5). METHODS AND RESULTS: We assessed volumetric VH-IVUS parameters in a consecutive series of 473 male patients: fibrous, fibro-fatty, dense calcium (DC), necrotic core (NC), and a calculated NC/DC ratio. Patients' age was 61 ± 11 years, with 27% smokers and 69% having a lipid disorder. The NC/DC ratio was the only VH-IVUS parameter related to both TC/HDL ratio (r = 0.18, P= 0.0008) and low-density lipoprotein cholesterol levels (r = 0.17, P= 0.002); had a negative correlation with HDL-C levels (r = -0.11, P= 0.03); and was higher for smokers [median 1.98 (1.35-3.18)] vs. non-smokers [median 1.70 (1.23-2.53), P= 0.006]. An NC/DC value >3 was the threshold that best identified smokers and/or patients presenting TC/HDL >5 (odds ratio 3.0, 95% CI 1.7-4.9, P= 0.0001), and receiver-operator curves showed the superiority of the NC/DC ratio [area under curve (AUC) 0.64, P < 0.0001] over %DC (AUC 0.58, P= 0.006) or %NC (AUC 0.51, P= 0.43) to identify these patients. CONCLUSION: The ratio of NC to calcification detected by VH-IVUS in diseased coronary segments is related to known risk factors for SCD and, thus, may be associated with a worse prognosis.

Necrotic core and its ratio to dense calcium are predictors of high-risk non-ST-elevation acute coronary syndrome.

Increased creatine kinase-MB levels and ST-segment depression are well-known prognostic factors in the setting of non-ST-elevation acute coronary syndrome (ACS). We hypothesized a relationship between virtual histology intravascular ultrasound (VH-IVUS) findings and these prognostic factors. We performed "whole vessel" VH-IVUS analysis in culprit arteries of 225 patients with ACS and measured the 4 basic VH-IVUS coronary plaque components--fibrous, fibrofatty, dense calcium (DC), and necrotic core (NC)--and calculated a NC/DC ratio. Patients' age was 62 +/- 11 years; 72% were men and 23% had diabetes. Only the NC/DC ratio had a positive association with creatine kinase-MB levels (r = 0.21, p = 0.03), and it was significantly higher for patients with ST-depression compared with those with non-ST-depression ACS (1.97 +/- 1.46 vs 1.58 +/- 1.10, p = 0.02). Sensitivity and specificity curves determined that a NC/DC value > or =2 (odds ratio 3.8, p = 0.01) and percentage of NC > or =6 (odds ratio 3.1, p = 0.04) were thresholds that best separated patients with high-risk non-ST-elevation ACS from those without abnormal creatine kinase-MB or ST depression. Patients with both predictors had significantly higher total cholesterol (204.7 +/- 60.5 vs 173.6 +/- 44.3 mg/dl, p = 0.01), higher low-density liprotein cholesterol (132.5 +/- 49.8 vs 101.3 +/- 33.2 mg/dl, p = 0.02), and more myocardial injury (creatine kinase-MB value of 42 +/- 38 vs 12 +/- 21, p = 0.01) than patients with no predictors. In conclusion, VH-IVUS analysis showed that the percentage of NC and its ratio to DC in diseased coronary segments are positively associated with a high-risk ACS presentation.

Nonrandomized comparison of coronary stenting under intravascular ultrasound guidance of direct stenting without predilation versus conventional predilation with a semi-compliant balloon versus predilation with a new scoring balloon.

This study was conducted to determine the influence of lesion preparation using the AngioSculpt balloon on final stent expansion. Stent expansion remains an important predictor of restenosis and subacute thrombosis, even in the drug-eluting stent (DES) era. In these patients, the role of different predilation strategies has yet to be established. Two hundred ninety-nine consecutive de novo lesions treated with 1 >2.5-mm DES (Cypher or Taxus) under intravascular ultrasound guidance without postdilation, using 3 implantation strategies, were studied: (1) direct stenting without predilation (n = 145), (2) predilation with a conventional semi-compliant balloon (n = 117), and (3) predilation with the AngioSculpt balloon (n = 37). Stent expansion was defined as the ratio of intravascular ultrasound-measured minimum stent diameter and minimum stent area to the manufacturer's predicted stent diameter and area. These ratios were larger after AngioSculpt predilation, and a greater percentage of stents had final minimum stent areas >5.0 mm(2) (another commonly accepted criterion of adequate DES expansion). Lesion morphology, stent and lesion length, and reference vessel size did not affect DES expansion. In conclusion, in this observational, nonrandomized study, pretreatment with the AngioSculpt balloon enhanced stent expansion and minimized the difference between predicted and achieved stent dimensions.

Intravascular ultrasound assessment of drug-eluting stent expansion.

BACKGROUND: In the drug-eluting stent (DES) era, stent expansion remains an important predictor of restenosis and subacute thrombosis. Compliance charts are developed to predict final minimum stent diameter (MSD) and area (MSA). The objectives of the study were (1) to assess DES expansion by comparing intravascular ultrasound (IVUS)-measured MSD and MSA against the values predicted by compliance charts and (2) to compare each DES against its bare-metal stent (BMS) equivalent. METHODS: We enrolled 200 patients with de novo coronary lesions treated with single, >2.5-mm Cypher (Cordis, Johnson & Johnson, Miami Lakes, FL) (sirolimus-eluting stent [SES], 133 patients) or Taxus (Boston Scientific, Natick, MA) (paclitaxel-eluting stent [PES], 67 patients) stent under IVUS guidance without another postdilation balloon. We used a comparison cohort of 65 equivalent BMS (Express 2 [Boston Scientific], 37 patients; Bx Velocity [Cordis, Johnson & Johnson], 28 patients) deployed under similar conditions. RESULTS: The DES achieved only 75% +/- 10% of predicted MSD and 66% +/- 17% of predicted MSA; this was similar for SES and PES. Furthermore, 24% of SES and 28% of PES did not achieve a final MSA of 5 mm(2), a consistent predictor of DES failure. The SES achieved 75% +/- 10% of predicted MSA versus 75% +/- 9% for Bx Velocity (P = .9). The PES achieved 79.9% +/- 14% of predicted MSA versus 79% +/- 10% for Express 2 (P = .8). Lesion morphology, arc and length of calcium, stent diameter and length, and implantation pressures did not affect expansion. CONCLUSIONS: Compliance charts fail to predict final MSD and MSA. A considerable percentage of DES does not achieve minimum standards of stent expansion. The SES and PES achieve similar expansion to their BMS platform, indicating that the polymer coating does not affect DES expansion in vivo. However, stent expansion cannot be predicted from preintervention IVUS lesion assessment.