Reference External Elastic Membrane Area Research Articles

A new intravascular ultrasound-guided stenting strategy compared with angiography on stent expansion and procedural outcomes in patients with positive lesion remodeling.

We investigated the role of a new intravascular ultrasound (IVUS)-guided stenting strategy versus angiography on optimal stent expansion (OSE) and procedural outcomes in patients with positive lesion remodeling. There are no IVUS criteria on how to achieve OSE. A total of 100 patients were assigned to a new IVUS-guided stenting strategy (IVUS group) versus angiography-guided stenting (Angio group). In the IVUS group, among patients with positive lesion remodeling, defined as a remodeling ratio (RR; lesion external elastic membrane (EEM) area/distal reference EEM area) >1.05, the stent was expanded with a balloon sized to the distal reference EEM diameter. In the Angio group, the stent was expanded by visual estimation. In both groups, IVUS was performed after postdilation. Minimum stent area (MSA) and stent volume index were significantly larger in the IVUS versus Angio group (7.1 ± 1.9 vs. 5.9 ± 1.5 mm2 , and 8.7 ± 2.1 vs. 7.5 ± 1.8 mm3 /mm, respectively; p < .01). The percentages of OSE, defined as an MSA ≥5.4 mm2 , MSA ≥90% of distal reference lumen area (DRLA), or MSA > DRLA, were significantly higher in the IVUS versus Angio group (80 vs. 56%, 78 vs. 54%, and 71 vs. 38%, respectively; p < .01). Stent underexpansion, malapposition, and residual reference segment stenosis were significantly higher in the Angio versus IVUS group (44 vs. 12%, 16 vs. 4%, and 12 vs. 0%, respectively; p < .05). In the IVUS group, owing to positive remodeling, there was no incidence of dissection or perforation. This new strategy of IVUS-guided stenting in patients with positive lesion remodeling, compared with angiography, significantly increased stent expansion and decreased stent underexpansion, malapposition, and residual reference segment stenosis with no complications.

Impact of IVUS-Derived Vessel Size on Midterm Outcomes After Stent Implantation in Femoropopliteal Lesions

Purpose: To identify intravascular ultrasound (IVUS) findings that predict midterm stent patency in femoropopliteal (FP) lesions. Materials and Methods: A retrospective analysis was undertaken of 335 de novo FP lesions in 274 consecutive patients (mean age 72.4±8.2 years; 210 men) who had IVUS assessment before and after successful stent implantation. The mean lesion length was 13.2±9.8 cm. The primary outcome was primary patency at 24 months, defined as freedom from major adverse limb event (MALE) and in-stent restenosis (ISR). MALE was defined as major amputation or any target lesion revascularization (TLR). ISR was defined by a peak systolic velocity ratio >2.4 by duplex ultrasonography. Logistic regression analyses were performed to identify independent predictors of stent patency at 24 months; the results are presented as the odds ratio (OR) and 95% confidence interval (CI). Receiver operator characteristic (ROC) curve analysis was performed to determine the optimal threshold for prediction of stent patency at 24 months. Results: Over the 24-month follow-up, 18 (7%) patients died and 43 (15%) of 286 lesions were responsible for MALE (42 TLRs and 1 major amputation). Primary patency was estimated at 82.5% (95% CI 78.1% to 86.9%) at 12 months and 73.2% (95% CI 67.9% to 78.5%) at 24 months. Multivariable analysis revealed that longer lesion length (OR 0.89, 95% CI 0.82 to 0.97, p<0.01) was an independent predictor of declining patency, while cilostazol use (OR 3.45, 95% CI 1.10 to 10.78, p=0.03) and increasing distal reference external elastic membrane (EEM) area (OR 1.18, 95% CI 1.02 to 1.37, p=0.03) were associated with midterm stent patency. ROC curve analysis identified a distal reference EEM area of 29.0 mm2 as the optimal cut-point for prediction of 24-month stent patency (area under the ROC curve 0.764). Kaplan-Meier estimates of 24-month primary patency were 83.7% (95% CI 78.3% to 89.2%) in lesions with a distal EEM area >29.0 mm2 vs 53.1% (95% CI 42.9% to 63.3%) in those with a distal EEM area ≤29.0 mm2 (p<0.001). Conclusion: In FP lesions with a larger distal vessel area estimated with IVUS, stent implantation can be considered as a reasonable treatment option, with the likelihood of acceptable midterm results.

Study of the features of coronary artery atheromatous plaque using intravascular ultrasound in patients with impaired glucose tolerance

ObjectiveWe used intravascular ultrasound (IVUS) to analyze the features of coronary artery atheromatous plaque in patients with impaired glucose tolerance and mild-to-moderate angiographic coronary stenosis. The aim was to determine the clinical significance of plaque characteristics as well as the relationship between hemoglobin A1c (HbA1c) levels and coronary artery lesions. MethodsHbA1c levels were evaluated in 85 patients (96 lesions), of whom 46 had impaired glucose tolerance (IGT Group) and 39 had normal blood glucose (NBG Group). IVUS was used to analyze the lesion vessel of both groups qualitatively and quantitatively. The external elastic membrane area (EEMA), minimal lumen area (MLA), plaque area (PA), and plaque burden (PB) were measured for both the target lesion and the reference segments (reference external elastic membrane area (REEMA), reference minimal lumen area (RMLA), reference plaque area (RPA), and reference plaque burden (RPB), respectively). ResultsHbA1c levels were significantly higher in the IGT Group than in the NBG Group (P < 0.05). In the IGT Group there was more soft plaque, eccentric plaque, and positive remodeling, and less calcification, while in the NBG Group there was much harder plaque and calcification, no reconstruction, and negative remodeling (P < 0.05). MLA was smaller in the IGT Group than in the NBG Group, while EEMA, PA, and PB were clearly greater (P < 0.05). In the meantime, RMLA was clearly smaller in the IGT Group than in the NBG Group, while RPA and RPB were greater (P < 0.05). HbA1c levels were positively correlated with PA and PB, and negatively correlated with MLA. ConclusionIVUS is very valuable for the evaluation of mild-to-moderate coronary lesions. The coronary artery lesions in patients with IGT are more serious and widespread than those in patients with NBG. HbA1c levels might be of some value in assessing the severity of coronary artery lesions.

Study on the Features of Coronary Artery Atheromatous Plaque for Patients with Impaired Glucose Tolerance when Applying Intravascular Ultrasound

Objective: By applying Intravascular Ultrasound (IVUS) to patients with mild-to-moderate coronary stenosis defined by Coronary Angiography (CAG), it is analyzed on the features of coronary artery atheromatous plaque for patients with impaired glucose tolerance and discussed about the clinical significance as well as the relationship between HbA1c levels and coronary artery lesion. Methods: HbA1c testing was applied to 85 patients (a total of 96 lesions) with 46 cases in Group of Impaired Glucose Tolerance (IGT Group) and 39 cases in Group of Normal Blood Glucose (NBG Group). IVUS was applied to qualitatively and quantitatively analyse the lesion vessel of both groups. Measurement was done both to target lesion for data of External Elastic Membrane Area (EEMA), Minimal Lumen Area (MLA), Plaque Area (PA), Plaque Burden (PB), and to the reference segments for data of Reference External Elastic Membrane Area (REEMA), Minimal Lumen Area (RMLA), Plaque Area (RPA), Plaque Burden (RPB). Results: The level of HbA1c in IGT Group was significantly higher than that in NBG Group (P < 0.05). For IGT Group, there were more soft plaque, eccentric plaque, positive remodeling and less calcification while for NBG Group, there were more performance for the hard plaque, calcification, no reconstruction and negative remodeling (P < 0.05). For IGT Group, MLA was less than NBG Group while EEMA, PA and PB were obviously higher than NBG Group (P < 0.05). In the meantime, RMAL was clearly less than NBG Group while RPA and RPB were higher than NBG Group (P < 0.05). HbA1c levels was positively correlated with PA, PB, but negatively correlated with MLA. Conclusion: IVUS shows a higher value to the evaluation of mild-to-moderate coronary lesions. The coronary artery lesions of IGT Group were more serious and widespread than that of NBG Group, and the level of HbA1c might provide some value for the judgment of the severity of coronary artery lesion.

In vivo association between positive coronary artery remodelling and coronary plaque characteristics assessed by intravascular optical coherence tomography

Positive coronary arterial remodelling has been shown to be associated with unstable coronary syndromes and ex vivo histological characteristics of plaque vulnerability such as a large lipid core and high macrophage content. The aim of this study is to evaluate the in vivo association between coronary artery remodelling and underlying plaque characteristics identified by optical coherence tomography (OCT). OCT is a unique imaging modality capable of characterizing these important morphological features of vulnerable plaque. OCT and intravascular ultrasound imaging was performed at corresponding sites in patients undergoing catheterization. OCT plaque characteristics for lipid content, fibrous cap thickness, and macrophage density were derived using previously validated criteria. Thin-cap fibroatheroma (TCFA) was defined as lipid-rich plaque (two or more quadrants) with fibrous cap thickness <65 microm. Remodelling index (RI) was calculated as the ratio of the lesion to the reference external elastic membrane area. A total of 54 lesions from 48 patients were imaged. Positive remodelling compared with absent or negative remodelling was more commonly associated with lipid-rich plaque (100 vs. 60 vs. 47.4%, P = 0.01), a thin fibrous cap (median 40.2 vs. 51.6 vs. 87 microm, P = 0.003) and the presence of TCFA (80 vs. 38.5 vs. 5.6%, P < 0.001). Fibrous cap macrophage density was also higher in plaques with positive remodelling showing a positive linear correlation with the RI (r = 0.60, P < 0.001). Coronary plaques with positive remodelling exhibit characteristic features of vulnerable plaque. This may explain the link between positive remodelling and unstable clinical presentations.

Correlation Between Morphologic Characteristics and Local Temperature Differences in Culprit Lesions of Patients With Symptomatic Coronary Artery Disease

The purpose of this study was to investigate the possible correlation between morphologic and functional characteristics of culprit lesions (CL) in patients with acute coronary syndromes (ACS) and chronic stable angina (CSA). Intravascular ultrasound (IVUS) provides morphologic assessment and intracoronary thermography (ICT) evaluates the local inflammatory activation of CL. Eighty-one consecutive patients, 48 with ACS and 33 with CSA, were enrolled. Ratio of lesion to reference external elastic membrane area, indicated by IVUS, was defined as positive remodeling index (pRi) (> or =1) or negative remodeling index (nRi) (<1). We also investigated the existence of ruptured plaque (rp) in the CL. By ICT temperature difference (DeltaT) between the CL and the proximal vessel wall was measured. Patients with ACS had greater remodeling index than patients with CSA (1.15 +/- 0.18 vs. 0.90 +/- 0.12; p < 0.01), as well as increased DeltaT (0.08 +/- 0.03 degrees C vs. 0.04 +/- 0.02 degrees C; p < 0.01). Patients with pRi had higher DeltaT than patients with nRi (0.07 +/- 0.03 degrees C vs. 0.04 +/- 0.02 degrees C; p < 0.001). In patients with nRi there was no difference in DeltaT between ACS and CSA (p = 0.22). Patients with rp had increased DeltaT compared with patients without rp (0.09 +/- 0.03 degrees C vs. 0.05 +/- 0.02 degrees C; p < 0.01). Multivariate analysis showed that DeltaT was independently correlated with the presence of rp, pRi, and ACS. The present study showed that culprit lesions with plaque rupture and positive arterial remodeling have increased thermal heterogeneity, although in certain patients a discrepancy between morphogic and functional characteristics was observed. A combination of morphologic and functional examination may offer additional diagnostic and prognostic information.

Static and serial assessments of coronary arterial remodeling are discordant: An intravascular ultrasound analysis from the Reversal of Atherosclerosis with Aggressive Lipid Lowering (REVERSAL) trial

Arterial remodeling is a major determinant of the clinical manifestations of coronary artery disease. Assessment of arterial remodeling with intravascular ultrasound (IVUS) used to rely on comparing the external elastic membrane (EEM) areas of lesion and reference sites at a single time point (static assessment). Recently, performance of serial IVUS provided the opportunity for direct assessment of remodeling. Our aim was to study the concordance of the static and serial methods. We identified 210 focal coronary lesions on the baseline IVUS interrogations of the REVERSAL trial. A follow-up IVUS was performed at 18 months. Static assessment was performed by calculating the remodeling index (RI) (lesion EEM area / reference EEM area) and serial assessment by comparing the changes in atheroma and EEM areas at follow-up. Using the serial method, there was a 1.24 mm2 increase in EEM area for every 1 mm2 increase in atheroma area at the lesion site, which was indicative of expansive (overcompensatory) remodeling. By using the static method, the RI was paradoxically lower at follow-up (1.062 +/- 0.15 at baseline vs 1.027 +/- 0.14 at follow-up, P < .001), indicating a trend toward constrictive remodeling. The reason for decreased RI at follow-up was the relatively larger expansion of the EEM areas at the reference sites. Static and serial assessments of arterial remodeling are discordant. This is due to concomitant remodeling of the reference sites used in the static assessment. Intravascular ultrasound performed at a single point in time does not reflect the dynamic remodeling response.

Determinants of Arterial Wall Remodeling During Lipid-Lowering Therapy

Coronary plaque progression and instability are associated with expansive remodeling of the arterial wall. However, the remodeling response during plaque-stabilizing therapy and its relationship to markers of lipid metabolism and inflammation are incompletely understood. Serial intravascular ultrasound (IVUS) data from the Reversal of Atherosclerosis with Aggressive Lipid Lowering Therapy (REVERSAL) trial were obtained during 18 months of intensive versus moderate lipid-lowering therapy. In a subgroup of 210 patients, focal coronary lesions with mild luminal narrowing were identified. Lumen area, external elastic membrane (EEM) area, and plaque area were determined at the lesion and proximal reference sites at baseline and during follow-up. The remodeling ratio (RR) was calculated by dividing the lesion EEM area by the reference EEM area. The relationship between the change in remodeling, change in plaque area, lipid profile, and inflammatory markers was examined. At the lesion site, a progression in plaque area (8.9+/-25.7%) and a decrease in the RR (-3.0+/-11.2%) occurred during follow-up. In multivariable analyses, the percentage change in plaque area (P<0.0001), baseline RR (P<0.0001), baseline lesion lumen area (0.019), logarithmic value of the change in high-sensitivity C-reactive protein (P=0.027), and hypertension at baseline (P=0.014) showed a significant, direct relation with the RR at follow-up. Lesion location in the right coronary artery (P=0.006), percentage change in triglyceride levels (P=0.049), and age (P=0.037) demonstrated a significant, inverse relation with the RR at follow-up. Changes in LDL cholesterol, HDL cholesterol, and treatment group demonstrated no significant associations. Constrictive remodeling of the arterial wall was observed during plaque-stabilizing therapy with statin medications and appears related to their antiinflammatory effects.

Remodeling Index Compared to Actual Vascular Remodeling in Atherosclerotic Left Main Coronary Arteries as Assessed With Long-Term (≥12 Months) Serial Intravascular Ultrasound

We present the remodeling index (RI) versus serial intravascular ultrasound (IVUS) data. The RI, derived by comparing lesion external elastic membrane (EEM) cross-sectional area versus the reference at one time point, is used in various IVUS studies as a substitute of true remodeling (change in EEM over time), assuming that it represents true remodeling. We studied 46 non-stenotic left main arteries using serial IVUS (follow-up 18 +/- 8 months). Plaques were divided into subgroups according to the follow-up RI: follow-up RI >1 (n = 27) versus follow-up RI < or =1 (n = 19). Lesions with a follow-up RI >1 had an increase in lumen despite an increase in plaque because of an increase in EEM. Conversely, lesions with a follow-up RI < or =1 had a reduction in lumen as a result of both a plaque increase and EEM decrease. Overall, the follow-up RI correlated directly with changes in lesion site EEM (baseline-to-follow-up). Although there was no correlation between the follow-up RI and changes in reference EEM area, changes in reference EEM area did correlate directly with changes in lesion EEM area. In nearly 90% of lesions with a follow-up RI >1, there was a previously documented increase in EEM area. Using multivariate linear regression analysis, the follow-up RI was dependent on the baseline RI, the increase in lesion EEM area, and the decrease in reference EEM area. The follow-up RI was not dependent on changes in lesion plaque area. The vast majority of left main lesions with a remodeling index >1 had evidence of a previous increase in lesion-site EEM area.

Mo-S6:4 The place for vascular imaging data in the evidence package for new drugs for atherosclerosis: Regulatory principles

We present the remodeling index (RI) versus serial intravascular ultrasound (IVUS) data.The RI, derived by comparing lesion external elastic membrane (EEM) cross-sectional area versus the reference at one time point, is used in various IVUS studies as a substitute of true remodeling (change in EEM over time), assuming that it represents true remodeling.We studied 46 non-stenotic left main arteries using serial IVUS (follow-up 18 ± 8 months). Plaques were divided into subgroups according to the follow-up RI: follow-up RI >1 (n = 27) versus follow-up RI ≤1 (n = 19).Lesions with a follow-up RI >1 had an increase in lumen despite an increase in plaque because of an increase in EEM. Conversely, lesions with a follow-up RI ≤1 had a reduction in lumen as a result of both a plaque increase and EEM decrease. Overall, the follow-up RI correlated directly with changes in lesionsite EEM (baseline-to-follow-up). Although there was no correlation between the follow-up RI and changes in referenceEEM area, changes in reference EEM area did correlate directly with changes in lesion EEM area. In nearly 90% of lesions with a follow-up RI >1, there was a previously documented increase in EEM area. Using multivariate linear regression analysis, the follow-up RI was dependent on the baseline RI, the increase in lesion EEM area, and the decrease in reference EEM area. The follow-up RI was not dependent on changes in lesion plaque area.The vast majority of left main lesions with a remodeling index >1 had evidence of a previous increase in lesion-site EEM area.

Association of Plaque Characterization by Intravascular Ultrasound Virtual Histology and Arterial Remodeling

Positive remodeling is more often observed in lesions of patients who have acute coronary syndromes or vulnerable (rupture-prone) plaques. However, there are few data that correlate plaque morphology, composition, and arterial remodeling in vivo. We evaluated coronary plaque characterization of lesions with positive remodeling using intravascular ultrasound (IVUS) radiofrequency data analysis. Seventy-seven nonbifurcation native coronary lesions (in 50 patients) were imaged in vivo using 30-MHz IVUS transducers. Lesions were classified into 4 plaque types, fibrous, fibrofatty, dense calcium, and necrotic core, by using processing of the radiofrequency signal validated in vitro. The remodeling index was calculated as the lesion external elastic membrane area divided by the proximal reference external elastic membrane area. Lesions were divided into 2 groups: positive remodeling (remodeling index>1.0, 26 lesions) and intermediate/negative remodeling (remodeling index<or=1.0, 51 lesions). Total plaque volume and the volume of each plaque type were averaged over the length of the lesion. Reference segment plaque compositions were similar. Mean lesion fibrofatty plaque area was significantly larger in lesions with positive remodeling than in lesions with intermediate/negative remodeling (1.2+/-0.7 vs 0.8+/-0.4 mm2, p=0.001; 26.3+/-6.6% vs 19.8+/-5.7%, p<0.001, of total plaque volume). The same results were obtained at the minimum lumen site and in the subgroup of patients who had acute coronary syndromes. Further, there was a linear relation between remodeling index and fibrofatty plaque area (r=0.26, p=0.02). In conclusion, in vivo IVUS radiofrequency data analysis demonstrates that positive remodeling occurs in lesions with more fibrofatty plaque.

Effect of disease eccentricity on compensatory remodeling of coronary arteries: evidence from intravascular ultrasound before interventions

Background: Compensatory remodeling occurs to maintain lumen area in human coronary vessels. However, few data exist regarding the relationship between vessel remodeling and plaque distribution. Therefore, we studied coronary sites with or without remodeling by intravascular ultrasound and correlated with disease distribution. Methods and Results: A total of 90 coronary sites with significant stenosis (>50%) from 80 patients were examined before interventions. For identifying the vessel remodeling, external elastic membrane (EEM) area was measured at the stenotic sites and the adjacent proximal and distal sites. The reference EEM area was calculated by averaging proximal and distal EEM areas, and percent enlargement of the EEM area was calculated by the formula: {(stenosis EEM area−reference EEM area)/reference EEM area}×100. Plaque area was determined by reducing the lumen from EEM areas. The maximal (max) and minimal (min) distances from the center of the lumen to the EEM were also measured, and the disease eccentricity index was calculated by the formula: {(max−min)/max}. The lesion was defined as eccentric if the index was >0.5 and as concentric if ≤0.5. There were 39 eccentric and 51 concentric lesions. The enlargement remodeling was observed at 32 lesions with the enlargement of EEM area of 28.0±16.0% (5.5 to 71.3%). Enlargement was more frequently observed in the eccentric than in concentric lesions ( P<0.05). However, within 32 stenoses, which showed enlargement, there was no difference in enlargement between eccentric ( n=19, 25.6±21.0%) and concentric lesions ( n=13, 21.5±12.0%). Also, there was no statistical correlation between the increase in plaque area and % enlargement of EEM area irrespective of plaque morphology. Conclusions: These data demonstrate that in advanced coronary disease compensatory enlargement occurs more frequently at the eccentric than concentric coronary lesions. However, the EEM area was limited to expand regardless of the disease morphology.

909-26 There are Gender-Related Differences in Vessel Size, but not In Target Lesion Plaque Composition: A Pre-Intervention Intravascular Ultrasound Study

Pre-intervention intravascular ultrasound imaging was used to assess the presence of gender-related differences in 627 focal, significant (quantitative angiographic diameter stenosis = 67 ± 16%), de novo, native vessel lesions in 465 males and 162 females (ages 60 ± 12 yrs). Lesion site external elastic membrane (EEM), lumen, and plaque + media (P + M) cross-sectional areas and % cross-sectional narrowing (%CSN = P + M/EEM were compared to a proximal reference site (most normal looking cross-section within 10 mm of the lesion, but before major side branches). Females Males p Reference EEM area (mm 2 ) 17.8 ± 5.6 19.9 ± 7.0 0.0006 Reference lumen area (mm 2 ) 8.9 ± 3.2 9.8 ± 4.0 0.013 Reference P+ M area (mm 2 ) 6.8 ± 11.6 7.2 ± 14.3 NS Reference % CSN 48.5 ± 12.9 50.1 ± 12.1 NS Lesion EEM area (mm 2 ) 17.6 ± 5.8 20.1 ± 5.5 0.0098 Lesion lumen area (mm 2 1.8 ± 0.8 1.9 ± 1.1 NS Lesion P + M area (mm 2 ) 15.8 ± 5.7 17.7 ± 6.9 0.0097 Lesion % CSN 88.8 ± 6.2 89.7 ± 63 NS Lesion/Reference EEM area 1.04 ± 0.24 1.00 ± 0.21 NS Lesion/Reference P + M area 2.19 ± 1.14 2.02 ± 213 NS There were no gender-related differences in lesion eccentricity (maximum/minimum P + M thickness = 2.8 ± 2.6 vs 3.1 ± 2.6), lesion or reference site plaque composition (frequency of fibrocalcific plaque elements), arc of calcium (104 ± 117° vs 105 ± 106°), or calcium distribution (superficial vs deep). We Conclude: Pre-intervention intravascular ultrasound imaging failed to detect any qualitative differences in de novo target lesion plaque composition or distribution in females compared to males. Arteries were smaller in females (smaller reference lumen and EEM areas and smaller lesion site EEM areas). However, the extent of compensatory arterial remodeling was similar (no difference in reference site and lesion site %CSN or in lesion/reference EEM area). The reduced target lesion plaque cross-sectional area in females can be explained entirely by the the smaller arterial size (no difference in lesion/reference P + M area).

909-23 Increased Plaque Burden Affects Procedural Outcomes in Total Occlusions: An Intravascular Ultrasound Study

In an attempt to understand the pathology and results of transcatheter therapy of total occlusions, intravascular ultrasound imaging of 43 de novo total occlusions was compared to 620 focal, significant (quantitative angiographic diameter stenosis = 66 ± 15%), de novo, native vessel lesions in 465 males and 162 females ages 60 ± 12 yrs. Total occlusions were defined angiographically as abrupt vessel cutoff with TIMI 0 or 1 flow. Lesion site external elastic membrane (EEM), lumen, and plaque + media (P + M) cross-sectional areas and % cross-sectional narrowing (%CSN = P + M/EEM) were compared to a proximal reference site (most normal looking cross-section within 10 mm of the lesion, but before major side branches). Total Occlusion NonTotal p Reference EEM area (mm 2 ) 18.5 ± 7.6 19.4 ± 6.6 NS Reference lumen area (mm 2 ) 9.1 ± 4.0 96 ± 39 NS Reference % CSN 49.0 ± 12.5 49.6 ± 12.3 NS Pre-intervention ultrasound Lesion EEM area (mm 2 ) 248 ± 14.8 190 ± 62 0.0043 Lesion lumen area (mm 2 ) 1.3 1.9 ± 1.1 0.0013 Lesion P + M area (mm 2 ) 23.5 ± 14.8 17.1 ± 6.1 0.0013 Post-intervention ultrasound Lesion lumen area (mm 2 ) 5.1 ± 2.2 6.3 ± 2.5 0.0062 Lesion %CSN 73.3 ± 8.2 68.6 ± 10.7 0.0086 Reference site measurements were similar in total and nontotal occlusions. Total occlusions had a larger plaque mass (23.5 vs 17.1 mm 2 ), a difference that could not be explained by the small difference in pre-intervention lumen area (1.3 vs 1.9 mm 2 ). The larger plaque mass was associated with greater compensatory arterial remodeling (larger EEM area and lesion/reference EEM). A larger plaque mass also contributed to a larger postintervention %CSN. Furthermore, despite a similar pattern of transcatheter device use, the post-intervention lumen area was smaller in total occlusions. Pre-intervention intravascular ultrasound imaging shows that despite significant compensatory dilatation, an increased plaque mass in total occlusions results in a smaller post-procedural lumen area and a larger residual %CSN. These findings may explain more frequent episodes of restenosis following angioplasty of total occlusions and may suggest a treatment strategy of aggressive plaque removal andlor stent placement in these lesions.