Shrinkage of the distal renal artery 1 year after stent placement as evidenced with serial intravascular ultrasound.

The objective of this study was to determine the quantitative intravascular ultrasound (IVUS) and angiographic changes that occur during 1 year follow-up after renal artery stent placement, given that restenosis continues to be a limitation of renal artery stent placement. 38 consecutive patients with symptomatic renal artery stenosis treated with Palmaz stent placement were studied prospectively. IVUS and angiography were performed at the time of stent placement and at 1 year follow-up. At follow-up, angiographic restenosis was seen in 14% of patients. The lumen area in the stent, seen with IVUS, was significantly decreased from 24+/-5.6 mm(2) to 17+/-5.6 mm(2) (p<0.001) solely due to plaque accumulation. The distal main renal artery showed a significant decrease in lumen area owing to a significant vessel area decrease from 39+/-14.0 mm(2) to 29+/-9.3 mm(2) (p<0.001) without plaque accumulation. Angiographic analysis confirmed this reduction in luminal diameter and showed that the distal renal artery diameter at follow-up was significantly smaller than before stent placement (86+/-23.0% vs 104+/-23.9% of the contralateral renal artery diameter; p=0.003). Besides plaque accumulation in the stent, unexplained shrinkage of the distal main renal artery was evidenced with IVUS and angiography 1 year following stent placement.

Gamma radiation induces positive vascular remodeling after balloon angioplasty: a prospective, randomized intravascular ultrasound scan study.

BACKGROUND: Endovascular brachytherapy (EBT) has been shown to prevent restenosis after percutaneous transluminal coronary angioplasty (PTA) in both animal and clinical studies. However, as yet, the effect of EBT on peripheral arteries is unknown. OBJECTIVE: This intravascular ultrasound scan (IVUS) study evaluates the effect of EBT on the extent of plaque growth and vascular remodeling after PTA of the femoropopliteal artery. METHODS: Twenty-four patients with obstructive disease of the femoropopliteal artery underwent standard PTA. Patients were randomized to receive no additional therapy or additional EBT (192-Iridium) after PTA. IVUS investigation was performed after PTA and at 6-month follow-up. A comparison was made between patients without EBT (n = 16) and with EBT (n = 8) in the change in lumen, vessel, and plaque area and plaque dissections seen with IVUS at 6-month follow-up. RESULTS: At follow-up, IVUS revealed a significant difference in lumen area change between patients without and with EBT (-9% and +23%, respectively; P =.03). This difference was the result of a significant difference in vessel area change (+2% and +19%, respectively; P =.05). In both groups of patients, a similar increase in plaque area (+12% and +16%, respectively; P =.80) was encountered. Plaque dissections encountered immediately after PTA were absent at follow-up in patients without EBT, whereas in four of the eight patients with EBT, a persistent dissection was encountered. CONCLUSION: This randomized IVUS study showed that gamma-radiation after PTA has a positive effect on lumen dimensions at 6-month follow-up by inducing positive vascular remodeling (ie, vascular dilatation); gamma-radiation seemed not to affect plaque growth. In addition, gamma-radiation has an effect on the healing process of dissections after PTA.

Validation of transrectal ultrasonographic volumetry for orthotopic prostate tumours in mice.

Orthotopic human prostate tumour models in athymic nude mice are regarded as being most suitable for fundamental and pre-clinical research on prostate cancer. The anatomic localization of the tumour in the pelvis, however, provides little possibility for monitoring tumour growth or regression. To assess time-related changes in orthotopic tumour volume, we applied transrectal ultrasonography (TRUS) to the murine prostate. This technique has the advantages of allowing accurate monitoring of tumours during therapeutic manipulations and a reduction of animal use due to a reduction of sacrificing endpoints. To validate the TRUS method, the mouse prostate reconstitution model, RM-9, and the prostate-specific antigen (PSA) producing human prostate cancer xenograft PC-346 were used. Volumetric calliper measurements were performed with a 30 MHz ultrasound probe designed for intra-arterial use in humans. Tumour weight, determined at various time-points, was found to be closely related to actual tumour weight (R = 0.99) and, in the PC-346 model, to the level of PSA in the plasma. Furthermore, the interobserver variation for TRUS was low for tumours above 50 mg. Thus, TRUS for murine prostate tumours proves to be an accurate, reproducible and sensitive method.

Intravascular ultrasound evidence for stabilization of compensatory enlargement of the femoropopliteal segment after endograft placement.

PURPOSE: To document whether the vasodilatory response seen at the anastomotic segment 6 months after placement of a balloon-expandable endograft in the femoropopliteal segment progresses between 6 and 24 months. METHODS: Twelve patients (9 men; median age 65 years, range 47-75) treated with an investigational polytetrafluoroethylene (PTFE) endograft for obstructive disease of the femoropopliteal segment were studied with intravascular ultrasound (IVUS) immediately after placement and at 6 months (first follow-up period) and 24 months (second follow-up period). Matched IVUS cross sections derived from the endograft and the anastomotic segment were analyzed for changes in lumen (LA), vessel (VA), and plaque areas (PLA). RESULTS: Five patients had complete IVUS surveillance at both the first (mean 8 months, range 7-9) and second (mean 25 months, range 23-26) follow-up periods; 1 patient was lost to follow-up during the second interval, and another 6 were excluded owing to graft occlusion (n = 4) or no IVUS surveillance available (n = 2) during the second follow-up period. Matched IVUS cross sections derived from the endograft showed no significant change in LA during both follow-up periods (-8% and +1%, respectively). There was no evidence for intimal hyperplasia or endograft recoil. During both follow-up periods, IVUS cross sections derived from the anastomotic segment revealed significant increases in LA (+37% and +8%, respectively) and VA (+26% and +6%, respectively) (both p < 0.05). The change in PLA during both follow-up periods was not significant (+13% and +3%, respectively). CONCLUSIONS: The PTFE endograft seems to inhibit both intimal hyperplasia and constrictive remodeling. The short-term (6-month) vascular dilatory response seen at the anastomotic segment tends to stabilize at 2 years. Therefore, this endovascular anastomosis acts as an "ideal" end-to-end anastomosis.

Rationale and design for the SARIS trial; effect of statin on atherosclerosis and vascular remodeling assessed with intravascular sonography. Effect of Statin on Atherosclerosis and vascular Remodeling assessed with Intravascular Sonography.

PURPOSE: The SARIS study (effect of Statin on Atherosclerosis and vascular Remodeling assessed with Intravascular Sonography) is a prospective randomized multicenter trial designed to assess both morphological and functional cardiovascular effects of atorvastatin. METHODS: Participating centers will include 50 patients with normal to mildly elevated cholesterol levels eligible for balloon angioplasty and/or stent placement of the common iliac artery. Patients will be randomized to 1-year treatment with either low-dose (10 mg) or high-dose (80 mg) atorvastatin. The morphological effects of atorvastatin will be studied using intravascular ultrasound (IVUS); the effect of atorvastatin on both plaque volume and vascular remodeling seen at 1-year follow-up will be investigated. The functional cardiovascular effects of atorvastatin will be studied using dobutamine stress echocardiography (DSE); the effect of atorvastatin on myocardial coronary flow reserve at 6-months and 1-year follow-up will be investigated. The aims of the present study are noteworthy in respect that (1) IVUS is the only available technique to sensitively measure the effect of atorvastatin on both intimal hyperplasia and vascular remodeling, and (2) DSE is a non-invasive test to objectively quantify the effect of atorvastatin on the functionality of the coronary artery.

Three-dimensional intravascular ultrasound assessment of abdominal aortic aneurysm necks.

PURPOSE: To document the accuracy of an automated analysis system for measuring lumen diameter and neck lengths of abdominal aortic aneurysms (AAAs) from intravascular ultrasound (IVUS) images and to describe additional features associated with 3-dimensional (3D) IVUS imaging. METHODS: Twenty-two aortic aneurysms were studied with IVUS. Lumen diameters obtained using the automated analysis system were compared with manual measurements from axial IVUS scans, as were neck lengths obtained using automated analysis versus those measured with the aid of a displacement sensing device. Automated analyses were repeated by a second observer. Agreement was expressed as the coefficient of variation (CV). RESULTS: Twenty proximal aortic, 6 distal aortic, and 3 iliac necks were available for analysis. Comparison between automated analysis and manual measurements for lumen diameter revealed a difference of 0.45 +/- 0.42 mm (mean +/- SD, Pearson's r = 0.99, p < 0.001, CV = 2.1%) and a difference of 0.05 +/- 0.12 cm (r = 0.99, p = 0.04, CV = 4.1%) for neck length. Interobserver difference for lumen diameter was 0.13 +/- 0.66 mm (r = 0.99, p < 0.001, CV = 3.4%) and 0.05 +/- 0.11 cm for length measurements (r = 0.99, p = 0.02, CV = 3.5%). The 3D IVUS imaging facilitated the identification of neck configuration. CONCLUSIONS: Automated analysis of IVUS images allows accurate measurement of the lumen diameter of proximal and distal AAA necks and gives length measurements comparable to those of manual analysis. Longitudinal display of IVUS images aids in the elucidation of neck anatomy.

Effect of simvastatin on restenosis after percutaneous transluminal angioplasty of femoropopliteal arterial obstruction.

This retrospective observational intravascular ultrasound study evaluated whether simvastatin therapy limits lumen area reduction 1-year after percutaneous transluminal angioplasty (PTA) by reducing reactive plaque growth, reducing reactive vasoconstriction, or both. This study showed that plaque growth is a general response 1 year after PTA regardless of the use of simvastatin; simvastatin has the potential to induce positive vascular remodeling, thereby reducing the occurrence of restenosis.

Reproducibility of calcified lesion quantification: a longitudinal intravascular ultrasound study.

In view of a prospective intravascular ultrasound (IVUS) study, the reproducibility of the extent of the calcified lesion in IVUS images derived from separate pull-back maneuvers was assessed. Patients (n = 34) were imaged with IVUS before and after percutaneous transluminal angioplasty (PTA) and at 1-y follow-up. In the presence of a calcified lesion, the largest arc and the length of the matched calcified lesions was assessed. Interobserver differences in arc measurements were low (< or = 0.7%), with low coefficients of variation (< or = 5.8%). Similarly, interexamination differences in arc and length measurements were small (< or = 1.1%), with low coefficients of variation (< or = 3.2%). At follow-up, a nonsignificant increase in both the arc (1.9%) and length (1.7%) of the calcified lesion was observed. This study showed that measurements of the calcified lesion are highly reproducible; changes seen at 1-y follow-up were not significant. We conclude that IVUS may be used to monitor the effect of medical intervention on the extent of the calcified lesion in a longitudinal study.

Progression of atherosclerosis at one-year follow-up seen with volumetric intravascular ultrasound in femoropopliteal arteries.

Volume measurements derived from intravascular ultrasound (IVUS) images assessed with an automated contour analysis system are accurate and reproducible. However, it is unknown to what extent plaque volume may change at follow-up. Therefore, the purpose of this longitudinal study is to examine whether IVUS is a sensitive means to identify progression of atherosclerosis and its derived primary end point plaque volume at 1-year follow-up. Patients (n = 11) undergoing percutaneous transluminal angioplasty (PTA) of the femoropopliteal artery were studied with IVUS immediately after PTA in the same session and at 1-year follow-up. Matched, well-identified vascular segments (3 to 4 cm in length), not subjected to PTA, imaged at baseline and after 1-year follow-up, were used for calculation of the longitudinal change in lumen, vessel and plaque volume, and mean plaque thickness. The median length of the selected vascular segments was 4 cm. At follow-up (12+/-2 months) a nonsignificant increase in lumen volume (2.3+/-11%), vessel volume (2.0+/-7.0%), and plaque volume (3.0+/-5.1%) was seen; the mean plaque thickness increase was 2.2+/-5.6%. In conclusion, progression of atherosclerosis implies changes in plaque and vessel volume, resulting in lumen volume change. This observation has important implications for future clinical trials aimed at monitoring the effect of pharmacologic agents on the progression and/or regression of atherosclerosis.

Stent placement for renal arterial stenosis: where do we stand? A meta-analysis.

PURPOSE: To perform a meta-analysis of renal arterial stent placement in comparison with renal percutaneous transluminal angioplasty (PTA) in patients with renal arterial stenosis. MATERIALS AND METHODS: Studies dealing with renal arterial stent placement (14 articles; 678 patients) and renal PTA (10 articles; 644 patients) published up to August 1998 were selected. A random-effects model was used to pool the data. RESULTS: Renal arterial stent placement proved highly successful, with an initial adequate performance in 98% and major complications in 11%. The overall cure rate for hypertension was 20%, whereas hypertension was improved in 49%. Renal function improved in 30% and stabilized in 38% of patients. The restenosis rate at follow-up of 6-29 months was 17%. Stent placement had a higher technical success rate and a lower restenosis rate than did renal PTA (98% vs 77% and 17% vs 26%, respectively; P <.001). The complication rate was not different between the two treatments. The cure rate for hypertension was higher and the improvement rate for renal function was lower after stent placement than after renal PTA (20% vs 10% and 30% vs 38%, respectively; P <.001). CONCLUSION: Renal arterial stent placement is technically superior and clinically comparable to renal PTA alone.

Vascular response in the femoropopliteal segment after implantation of an ePTFE balloon-expandable endovascular graft: an intravascular ultrasound study.

PURPOSE: To use intravascular ultrasound (IVUS) to document changes in vascular dimensions after placement of a balloon-expandable endograft. METHODS: Thirteen patients (9 men; mean age 62 years, range 47-75) treated with an investigational polytetrafluoroethylene endograft for obstructive disease of the femoropopliteal segment were studied with IVUS immediately after endograft implantation and at follow-up. Corresponding IVUS cross sections were analyzed for changes in lumen, vessel, and plaque areas seen inside the endograft, in the anastomotic segment, and in the remote arterial segment. RESULTS: A mean 6-month (range 1.5-9) follow-up was completed in 12 patients. Matched IVUS cross sections derived from within the endograft (n = 12) and at the endograft edges (n = 23) showed no change in lumen area (LA) in 17, reduction in 11, and dilatation in 7. Median changes within the endograft (+3%) were not significant (p = 0.28) and no neointima was found. Cross sections obtained at the anastomotic segment revealed a significant increase in LA (85%, p < 0.001), which was associated with a significant increase in both vessel area (VA) (42%, p < 0.001) and plaque area (PLA) (15%, p = 0.003) area. In the remote arterial segment, the change in LA was minimal (6%, p = 0.07), as were changes in the VA (9%, p = 0.04) and PLA (10%, p = 0.07). CONCLUSIONS: Following endograft placement, luminal changes within the endograft, at the endograft edges, and at the remote arterial segments were minimal. Intimal hyperplasia was not observed in the endograft. The distinct LA increase at the anastomotic segments was determined by the extent of VA and PLA change.

Reproducibility of volumetric quantification in intravascular ultrasound images.

The reproducibility of volume measurements in intravascular ultrasound (IVUS) images derived from separate pull-back manoeuvres remains to be elucidated. Patients (n = 23) were imaged with IVUS prior to (first series) and following percutaneous transluminal angioplasty (PTA) (second series). In 15 patients, one matched vascular segment (3-4 cm in length), not subjected to PTA, was used for analysis of lumen, vessel and plaque volume using an automated contour analysis system. Volume measurements assessed by two independent observers and in the two separate series were compared. Interobserver differences in volume measurements were small (< or =0.4%), with low coefficients of variation (< or =1.7%) and high correlation coefficients (r = 1.00). Differences in volume measurements obtained in the two separate series were small (< or =2.6%), with low coefficients of variation (< or = 8.6%) and high correlation coefficients (r = 0.97-0.99). In conclusion, volume measurements derived from IVUS images are highly reproducible. Therefore, IVUS may be used to monitor the progression/regression of atherosclerotic plaque volume in a longitudinal study.

Early experience with intravascular ultrasound in evaluating the effect of statins on femoropopliteal arterial disease: hypothesis-generating observations in humans.

The purpose of this study was to compare the vascular response seen with intravascular ultrasound (IVUS) at 1-year follow-up between statin-treated and non-statin-treated patients. Patients (n = 10) undergoing percutaneous transluminal angioplasty (PTA) of the femoropopliteal artery were studied with IVUS immediately after PTA and at 1-year follow-up. In nondilated matched vascular segments, the change in lumen, vessel, and plaque volume was assessed. In balloon-dilated matched vascular segments, the change in lumen, vessel, and plaque area was assessed. A comparison was made between statintreated (n = 5) and non-statin-treated patients (n = 5) in lumen, vessel, and plaque changes. At follow-up, both statin-treated and non-statin-treated patients showed a similar increase in plaque volume at the nondilated segment (+4% and +2%, respectively). In statin-treated patients the plaque volume increase was compensated by an increase in vessel volume (+2%), resulting in an increase in lumen volume (+1%). In non-statin-treated patients, on the other hand, the increase in plaque volume was associated with a decrease in vessel volume (-2%), resulting in a decrease in lumen volume (-4%). At the balloon-dilated segment a similar trend in changes of lumen, vessel, and plaque was encountered. Differences between both groups of patients were not statistically significant. Despite the nonsignificant nature of the observation, this small retrospective IVUS study may generate the hypothesis that statin therapy may contribute to superior long-term lumen dimensions by inducing positive vascular remodeling both in nondilated and balloon-dilated vascular segments.

Intravascular ultrasound evidence for coarctation causing symptomatic renal artery stenosis.

BACKGROUND: A recent study of human cadaveric renal arteries revealed that renal artery narrowing could be due not only to atherosclerotic plaque compensated for by adaptive remodeling, but also to hitherto undescribed focal narrowing of an otherwise normal renal arterial wall (ie, coarctation). The present study investigated whether vessel coarctation could be identified in patients with symptomatic renal artery stenosis (RAS). METHODS AND RESULTS: Consecutive symptomatic patients with angiographically proven atherosclerotic RAS who were referred for stent placement were studied by 30-MHz intravascular ultrasound before intervention (n=18) or after predilatation (n=18). Analysis included assessment of the media-bounded area and plaque area (PLA) at the most stenotic site and at a distal reference site (most distal cross-section in the main renal artery with normal appearance). Coarctation was considered present whenever the target/reference media-bounded area was

Endovascular stent-grafts for aneurysms of the femoral and popliteal arteries.

Our objective was to investigate the preliminary use of endovascular stent-grafts for the treatment of femoropopliteal artery aneurysm. Ten patients with an aneurysm of the femoropopliteal artery referred for endovascular treatment were investigated. The series consisted of patients with a true aneurysm of the superficial femoral artery (n = 2); a true aneurysm of the popliteal artery (n = 4); an aneurysmal dilatation of a Biograft bypass (n = 2); a false aneurysm of the superficial femoral aneurysm (n = 1); and a false aneurysm of a composite bypass (n = 1). In 8 of the 10 patients the stent-graft was composed of one or more Palmaz stents sutured to an ePTFE tube graft; in the other 2 patients a venous covering was used in combination with Palmaz stents. The procedure was guided by angiography and intravascular ultrasound. The results of our investigation showed that endovascular stent-grafting of aneurysms of the femoropopliteal artery is a feasible but experimental technique that should be restricted to a selected group of patients.

Conductance method for the measurement of cross-sectional areas of the aorta.

A modified conductance method to determine the cross-sectional areas (CSAs) of arteries in piglets was evaluated in vivo. The method utilized a conductance catheter having four electrodes. Between the outer electrodes an alternating current was applied and between the inner electrodes the induced voltage difference was measured and converted into a conductance. CSA was determined from measured conductance minus parallel conductance, which is the conductance of the tissues surrounding the vessel times the length between the measuring electrodes of the conductance catheter divided by the conductivity of blood. The parallel conductance was determined by injecting hypertonic saline to change blood conductivity. The conductivity of blood was calculated from temperature and hematocrit and corrected for maximal deformation and changes in orientation of the erythrocytes under shear stress conditions. The equations to calculate the conductivity of blood were obtained from in vitro experiments. In vivo average aortic CSAs. determined with the conductance method CSA(G) in five piglets, were compared to those determined with the intravascular ultrasound method CSA(IVUS). The regression equation between both values was CSA(G)=-0.09+1.00 x CSA(IVUS), r=0.97, n=53. The mean difference between the values was -0.29%+/-5.57% (2 standard deviations). We conclude that the modified conductance method is a reliable technique to estimate the average cross-sectional areas of the aorta in piglets.

Accurate assessment of abdominal aortic aneurysm with intravascular ultrasound scanning: validation with computed tomographic angiography.

PURPOSE: The purpose of this study was to assess the accuracy of intravascular ultrasound (IVUS) parameters of abdominal aortic aneurysm, used for endovascular grafting, in comparison with computed tomographic angiography (CTA). METHODS: This study was designed as a descriptive study. Between March 1997 and March 1998, 16 patients with abdominal aortic aneurysms were studied with angiography, IVUS (12.5 MHz), and CTA. The length of the aneurysm and the length and lumen diameter of the proximal and distal neck obtained with IVUS were compared with the data obtained with CTA. The measurements with IVUS were repeated by a second observer to assess the reproducibility. Tomographic IVUS images were reconstructed into a longitudinal format. RESULTS: IVUS results identified 31 of 32 renal arteries and four of five accessory renal arteries. A comparison of the length measurements of the aneurysm and the proximal and distal neck obtained with IVUS and CTA revealed a correlation of 0.99 (P <.001), with a coefficient of variation of 9%. IVUS results tended to underestimate the length as compared with the CTA results (0.48 +/- 0.52 cm; P <.001). A comparison of the lumen diameter measurements of the proximal and distal neck derived from IVUS and CTA showed a correlation of 0.93 (P <.001), with a coefficient of variation of 9%. IVUS results tended to underestimate aneurysm neck diameter as compared with CTA results (0.68 +/- 1.76 mm; P =.006). Interobserver agreement of IVUS length and diameter measurements showed a good correlation (r = 1.0; P <.001), with coefficients of variation of 3% and 2%, respectively, and no significant differences (0.0 +/- 0.16 cm and 0.06 +/- 0.36 mm, respectively). The longitudinal IVUS images displayed the important vascular structures and improved the spatial insight in aneurysmal anatomy. CONCLUSION: Intravascular ultrasound scanning results provided accurate and reproducible measurements of abdominal aortic aneurysm. The longitudinal reconstruction of IVUS images provided additional knowledge on the anatomy of the aneurysm and its proximal and distal neck.

In-vitro validation, with histology, of intravascular ultrasound in renal arteries.

OBJECTIVE: To investigate the feasibility of using intravascular ultrasound to characterize normal and diseased renal arteries. MATERIALS AND METHODS: Forty-four renal artery specimens from 21 humans, removed at autopsy, were studied with intravascular ultrasound in vitro. From each vascular specimen, two to four sets of corresponding intravascular ultrasound images and histologic sections were subjected to qualitative analysis. The renal arterial wall was considered normal by intravascular ultrasound when the wall thickness (intima and media) was 0.5 mm or less. On intravascular ultrasound imaging, a distinction was made between bright lesions with or without peripheral shadowing (i.e. calcification). Histological sections were examined and fibromuscular lesions were scored with or without calcifications. Quantitative analysis of a multitude of intravascular ultrasound cross-sections (interval 5 mm) included assessment of the lumen area, vessel area, plaque area and percentage area obstructed. The target site (smallest lumen area) was compared with a reference site (largest lumen area before the first major side branch). RESULTS: Of the 130 corresponding intravascular ultrasound images and histologic sections analysed, 55 were normal and 75 presented a bright lesion on ultrasound; in 31 lesions, peripheral shadowing was involved. The sensitivity of the intravascular ultrasound in detecting calcifications was 87%, and the specificity was 89%. Lumen area reduction at the target site was associated with vessel and plaque area enlargement in eight specimens, with plaque area enlargement in 12 specimens and with a vessel area reduction in 21 specimens. CONCLUSIONS: Intravascular ultrasound is a reliable technique for distinguishing renal arteries with or without a lesion. Both plaque development and local vessel narrowing may result in renal artery stenosis.

Plaque area increase and vascular remodeling contribute to lumen area change after percutaneous transluminal angioplasty of the femoropopliteal artery: an intravascular ultrasound study.

OBJECTIVE: The aim of the study was to assess the change in lumen area (LA), plaque area (PLA), and vessel area (VA) after percutaneous transluminal angioplasty (PTA) of the femoropopliteal artery. METHODS: This was a prospective study. Twenty patients were studied with intravascular ultrasound (IVUS) immediately after PTA and at follow-up examination. Multiple corresponding IVUS cross-sections were analyzed at the segments that were dilated by PTA (ie, treated sites; n = 168), including the most stenotic site (n = 20) and the nondilated segments (ie, reference sites; n = 77). RESULTS: At follow-up examination, both the PLA increase (13%) and the VA decrease (9%) resulted in a significant LA decrease (43%) at the most stenotic sites (P =.001). At the treated sites, the LA decrease (15%) was smaller and was caused by the PLA increase (15%). At the reference sites, the PLA increase (15%) and the VA increase (6%) resulted in a slight LA decrease (3%). An analysis of the IVUS cross-sections that were grouped according to LA change (difference >/=10%) revealed a similar PLA increase in all the groups: the type of vascular remodeling (VA decrease, no change, or increase) determined the LA change. At the treated sites, the LA change and the VA change correlated closely (r = 0.77, P <.001). At the treated sites, significantly more PLA increase was seen in the IVUS cross-sections that showed hard lesion or media rupture (P <.05). No relationship was found between the presence of dissection and the quantitative changes. CONCLUSION: At the most stenotic sites, lumen narrowing was caused by plaque increase and vessel shrinkage. Both the treated sites and the reference sites showed a significant PLA increase: the type of vascular remodeling determined the LA change at follow-up examination. The extent of the PLA increase was significantly larger in the IVUS cross-sections that showed hard lesion or media rupture.