Does the specific intravascular ultrasound criterion used to optimize stent expansion have an impact on the probability of stent restenosis?

Adjunctive Balloon Postdilatation after Stent Deployment: Is It Still Necessary with Drug-Eluting Stents?

Deployment of bare metal stents (BMS) with current stent delivery systems is often associated with suboptimal stent expansion. Adjunctive postdilatation with noncompliant balloons has improved stent expansion with BMS and has been associated with less need for target vessel revascularization (TVR). Drug-eluting stents (DES) have proven highly effective in reducing restenosis and TVR and are now being used in the great majority of percutaneous coronary interventions. Because of the very low rates of TVR with DES, many operators have felt that postdilatation may no longer be necessary. In this review, we present data showing that stent expansion of DES (like BMS) using current stent delivery systems is frequently suboptimal. Furthermore, smaller mimimal stent area (MSA) and stent underexpansion following deployment of DES are strong predictors of stent thrombosis and TVR. Adjunctive postdilatation with noncompliant balloons can increase MSA and decrease the frequency of suboptimal stent deployment and potentially can reduce the frequency of stent thrombosis and TVR. Despite the lack of evidence from randomized clinical trials, we believe the observational data support the use of adjunctive balloon postdilatation following deployment of DES in the great majority of patients.

Drug-Eluting Coronary Stents

The introduction and widespread use of coronary stents have been the most important advancement in the percutaneous treatment of coronary artery disease since the introduction of balloon angioplasty. Coronary artery stents reduce the rate of angiographic and clinical restenosis compared to balloon angioplasty. This angiographic restenosis was further reduced with the introduction of drug-eluting stents and hence further reduction in the frequency of major adverse cardiac events. Herein we present a comprehensive and up-to-date review about the use of drug-eluting stents in the treatment of coronary artery disease.

Incidence of stent under-deployment as a cause of in-stent restenosis in long stents

Although stent under-deployment (SU) has been associated with increased risk of in-stent restenosis, little data have been reported on the incidence of SU in patients presenting with clinical in-stent restenosis. In 59 patients referred for vascular brachytherapy and showing angiographic in-stent restenosis, we sought (1) to determine the incidence of SU using standard intravascular ultrasound (IVUS) criteria (2) to evaluate the effects of repeat angioplasty on further stent expansion. Stented length was 32+/-17 mm and diameter stenosis was 75+/-14%. Before re-intervention, the incidence of reduced absolute values of minimal stent cross-sectional area (MSCSA) varied from 69% (< or =8 mm2) to 15% (< or =5 mm2). After re-intervention, the incidence decreased to 24% (< or =8 mm2) (p = 0.0001) and 0% (< or =5 mm2) (p = 0.005). Before re-intervention, SU as assessed by relative criteria varied from 21% (80% mean reference lumen area or 90% minimum distal reference lumen area) to 28% (100% minimum reference lumen area). After re-intervention, the incidence of SU varied from 7% (90% minimum distal reference lumen area) (p = 0.0001 vs. pre) to 24% (55% mean reference EEM area) (p = ns). No change in strut apposition (97% pre vs. 100% post) nor in symmetry index (100% pre vs. post) was noted. From all criteria, the 90 and 100% minimum reference lumen area criteria were the most altered by repeat balloon dilatation, 21% pre vs. 7% post and 28% pre vs. 11% post, respectively. In conclusion, among patients presenting with severe angiographic in-stent restenosis, a significant number showed signs of SU whose incidence varied according to applied criteria. Significant stent re-expansion can be obtained following IVUS-guided repeat angioplasty irrespective of initial SU criteria.

Prevention of restenosis after coronary angioplasty

PURPOSE OF REVIEW

Despite numerous advances in coronary interventional techniques, the frequent occurrence of restenosis continues to plague interventional cardiology. With the widespread use of drug-eluting stents, there is a need to reexamine critically the roles of the various interventional techniques currently available.

RECENT FINDINGS

Drug-eluting stents have dramatically reduced the rates of restenosis and target vessel revascularization in a wide spectrum of patients with varying lesion morphologies. However, when restenosis does occur, it still tends to be dependent on the same factors that predict restenosis with bare metal stenting. The routine use of drug-eluting stents entails high initial costs to the health care system. Debulking as a means to improve outcomes after angioplasty has not lived up to expectations. Gene therapy is rapidly evolving into a viable means to reduce neointimal proliferation after angioplasty.

SUMMARY

Careful patient selection and attention to the procedure of stent deployment optimize the results of angioplasty with drug-eluting stents. Because of cost considerations, drug-eluting stents should be used in patients who are expected to have the greatest absolute benefit. In this context, when judiciously used, conventional balloon angioplasty and bare metal stenting still have a definite role in the management of patients with obstructive coronary artery disease.

Routine intravascular ultrasound scanning guidance of coronary stenting is not associated with improved clinical outcomes

PURPOSE

The purpose of the current study was to determine whether there is any incremental benefit to routine intravascular ultrasound (IVUS) guidance of percutaneous coronary intervention.

METHODS AND RESULTS

We compared the outcome of 796 patients who underwent an IVUS study (IVUS group) during the index stent procedure with 8274 patients who did not have an IVUS study (angiography group). The primary end point was the composite end point of death, myocardial infarction, or ischemia-driven target vessel revascularization within 9 months of the index stent procedure. There were statistically significant differences in multiple procedural characteristics. Most importantly, those patients who underwent an IVUS study had a larger postprocedural minimal lumen diameter and smaller postprocedural percent diameter stenosis. However, there was no significant difference between the IVUS group and the angiography group with respect to the primary end point (RR 1.10, 95% CI 0.91, 1.32) or any of the individual clinical end points. Adjustment for multiple clinical and procedural characteristics did not significantly alter these findings.

CONCLUSIONS

These data suggest that the routine performance of IVUS during stent placement influences the performance of the procedure, as judged by differences in procedural characteristics, but does not improve clinical outcome at 9 months.

Impact of final stent dimensions on long-term results following sirolimus-eluting stent implantation: serial intravascular ultrasound analysis from the sirius trial

OBJECTIVES

We assessed the predictive value of minimum stent area (MSA) for long-term patency of sirolimus-eluting stents (SES) implantation compared to bare metal stents (BMS).

BACKGROUND

Although MSA is a consistent predictor of in-stent restenosis, its predictive value in BMS is still limited because of biologic variability in the restenosis process.

METHODS

From the SIRolImUS (SIRIUS) trial, 122 cases (SES: 72; BMS: 50) with complete serial intravascular ultrasound (IVUS) (baseline and 8-month follow-up) were analyzed. Postprocedure MSA and follow-up minimum lumen area (MLA) were obtained. Based on previous physiologic studies, adequate stent patency at follow-up was defined as MLA >4 mm(2).

RESULTS

In both groups, a significant positive correlation was observed between baseline MSA and follow-up MLA (SES: p < 0.0001, BMS: p < 0.0001). However, SES showed higher correlation than BMS (0.8 vs. 0.65) with a higher regression coefficient (0.92 vs. 0.59). The sensitivity and specificity curves identified different optimal thresholds of MSA to predict adequate follow-up MLA: 5 mm(2) for SES and 6.5 mm(2) for BMS. The positive predictive values with these cutoff points were 90% and 56%, respectively.

CONCLUSIONS

In this SIRIUS IVUS substudy, SES reduced both biologic variability and restenosis, resulting in increased predictability of long-term stent patency with postprocedure MSA. In addition, SES had a considerably lower optimal MSA threshold compared to BMS.

Stenting after directional coronary atherectomy compared with directional coronary atherectomy alone and stenting alone: a serial intravascular ultrasound study

BACKGROUND

Directional coronary atherectomy prior to stent implantation (DCA-stent) is expected to be an effective approach to reduce restenosis. The purpose of this study was to determine whether DCA-stent has advantages over DCA alone or stenting alone using serial intravascular ultrasound (IVUS).

METHODS AND RESULTS

Serial (pre-, post- and follow-up) IVUS was performed in 187 native coronary lesions treated with each of the 3 strategies. External elastic membrane cross-sectional area (CSA), lumen CSA and plaque CSA were measured. Baseline characteristics were similar. Postprocedural lumen CSA was largest after DCA-stent (11.2+/-2.7 mm2) and DCA (10.8+/-2.5 mm2) than stenting alone (9.0+/-2.9 mm2) (p<0.0005). Follow-up lumen loss was similar. As a result, follow-up lumen CSA was largest after DCA-stent (DCA-stent: 9.1+/-3.4 mm2, DCA: 7.8+/-4.2 mm2, stent: 6.3+/-2.6 mm2, p<0.0005). There was a trend toward a lower rate of restenosis with DCA-stent (DCA-stent, 12.5%; DCA, 18.3%; stent, 18.8%; p=0.57).

CONCLUSIONS

DCA-stent is superior to both DCA alone and stent alone in terms of the ability to gain a larger lumen as assessed by IVUS.

Impact of the acute results on the long-term outcome after the treatment of in-stent restenosis: A serial intravascular ultrasound study

The current study used serial (postintervention and follow-up) intravascular ultrasound (IVUS) to assess the impact of acute results on long-term follow-up of patients with in-stent restenosis (ISR). All patients (n = 180) with serial IVUS studies of ISR lesions from the following gamma-irradiation brachytherapy trials were included: Washington Radiation for In-Stent Restenosis Trial (WRIST), Gamma-1, and Angiorad Radiation Technology for In-Stent Restenosis Trial in Native Coronaries (ARTISTIC). There were 106 irradiated and 74 placebo patients. Quantitative analysis was performed according to the American College of Cardiology Clinical Expert Consensus Document on Standards for Acquisition, Measurement and Reporting of IVUS. Images were acquired using motorized transducer pullback, cross-sectional analysis was performed every 1 mm, and volumetric and mean planar dimensions were calculated. The independent predictors for the absolute follow-up minimum lumen area (MLA) were the postintervention MLA, the postintervention minimum stent area, and the use of brachytherapy. Placebo patients lost 45% of the postintervention MLA while irradiated patients lost only 17% of the MLA. The independent predictors of the follow-up percent intimal hyperplasia (intimal hyperplasia volume divided by stent volume) and the independent predictors of the absolute increase in intimal hyperplasia were the postintervention percent intimal hyperplasia and the use of brachytherapy. Serial IVUS analysis shows that the follow-up MLA and percent intimal hyperplasia are dependent on the results obtained during the treatment of ISR lesions.

Direct stenting with a combined intravascular ultrasound-coronary stent delivery platform: a feasibility trial

IVUS is considered as the most accurate tool for the assessment of optimal stent deployment. Direct stenting has shown to be a safe, efficient, and resource-saving procedure in selected patients. In a prospective 1-month feasibility trial, a new combined IVUS-coronary stent delivery platform (Josonics Flex, Jomed, Helsingborn, Sweden) was evaluated during direct stenting in consecutive patients considered eligible for direct stenting. The feasibility endpoint was successful stent deployment without any clinical adverse event, while the efficacy endpoint was strategic adaptation according to standard IVUS criteria for optimal stent deployment at the intermediate phase (after a result considered angiographically optimal) and at the end of the intervention (after optimization according to IVUS standards). A total of 16 patients were successfully treated with this device without any major clinical complication. At the intermediate phase, optimal stent deployment was achieved in four patients only, while at the end only one patient had nonoptimal IVUS stent deployment. In particular, the minimal in-stent cross-section area increased from 6.3 +/- 1.2 to 8.3 +/- 2.5 mm(2). These preliminary data demonstrate the feasibility of direct stenting with a combined IVUS-stent catheter in selected patients and confirm the results from larger randomized trials on the impact of IVUS on strategic adaptations during coronary stent placement.

Is adjunctive balloon postdilatation necessary after coronary stent deployment? Final results from the POSTIT trial

Early-generation balloon-expandable stents required postdilatation with noncompliant balloons at high pressure to optimize stent deployment. The need for adjunctive balloon postdilatation with modern stent delivery systems is unknown. Patients undergoing elective stenting were randomized to Boston Scientific NIR, Guidant Tri-Star/Tetra, and Medtronic AVE S670 stents. The primary endpoint was optimum stent deployment defined as a minimal stent diameter (MSD) >/= 90% of the average reference lumen diameter assessed by intravascular ultrasound (IVUS) performed immediately following stent deployment. If, by operator assessment, the primary endpoint was not achieved with the stent delivery system, adjunctive postdilatation with noncompliant balloons was performed. Of 256 patients with IVUS studies adequate for core laboratory analysis, only 29% achieved optimum stent deployment with the stent delivery system. None of the baseline clinical or angiographic variables predicted optimum stent deployment. Of the procedural variables, the type of stent and nominal stent size were not predictors, but higher deployment pressures were associated with a higher frequency of optimum stent deployment (< 12 atm 14% vs. >/= 12 atm 36%; P = 0.007). The inability to achieve optimum stent deployment was not due to undersizing the stent delivery balloon, but rather to an inability of the stent delivery balloon to expand fully the stent to nominal size. In patients who underwent postdilatation, the frequency of achieving optimum stent deployment increased from 21% to 42%, minimal stent area increased from 6.6 +/- 2.2 to 7.8 +/- 2.3 mm(2), and MSD increased from 2.6 +/- 0.5 to 2.8 +/- 0.4 mm. These data stress the continued need for adjunctive balloon postdilatation with modern stent delivery systems. Cathet Cardiovasc Intervent 2003;59:184-192.

Intravascular ultrasound correlates of corrected TIMI framecount

The TIMI frame count (TFC) is an index of coronary blood flow, and a correction in TFC (CTFC) for left anterior descending artery (LAD) has also been proposed. However, the relationship between TFC and intravascular ultrasound (IVUS) parameters of culprit coronary arteries has not been reported. The aim of this study was to investigate IVUS-derived correlates of TFC before and after stenting, and to assess the validation of its correction for LAD. The study population was comprised of 38 patients with acute coronary syndrome or stable coronary artery disease studied by IVUS before and after stenting (LAD 21, circumflex 8, right coronary artery 9). For LAD, CTFC was calculated by dividing the TFC by 1.7. Preintervention luminal % area stenosis was 82 +/- 12.3%. Pre- and postintervention target lesion lumen areas were 1.8 +/- 0.5 mm2 and 8.5 +/- 0.5 mm2 (P<0.0001), and CTFC were 35.3 +/- 16.8 and 16.9 +/- 4.3 (P<0.0001), respectively. In the 76 IVUS studies, CTFC showed a good correlation to luminal % area stenosis (r = 0.69, P<0.001), and a good and negative correlation to target lesion lumen area (r = -0.70, P<0.001). Postprocedural improvement in CTFC showed a modest correlation to acute lumen gain (r = 0.5, P<0.05). With respect to culprit arteries, pre and postintervention IVUS parameters and CTFC, and net CTFC change after stenting were not different (P>0.05). However, uncorrected TFC of LAD was significantly higher than both the CTFC of LAD and TFC of the other two coronary arteries (P<0.05). We conclude that CTFC is closely correlated to target lesion luminal area and luminal % area stenosis whereas a modest correlation is present between improvement in CTFC and acute luminal gain due to stenting. Results from different coronary arteries with comparable IVUS parameters seem to support the validity of a correction in TFC.

Optimal deployment of third-generation stents: an intravascular ultrasound assessment

Third-generation intracoronary stents allow deployment at higher pressures, possibly obviating the need for high-pressure postdilations and also possibly reducing restenosis. This study evaluated the ability of the Tristar Coronary Stent System to produce optimal stent deployment as measured by intravascular ultrasound (IVUS) and quantitative coronary angiography in 46 patients. Optimal stent deployment was defined as minimal luminal area > 80% of the average of the proximal and distal reference luminal areas. After initial deployment, 74.5% of stents met criteria for optimal stent deployment by IVUS, with an average stent expansion ratio of 89.6%. Ten stents (18.2%) were postdilated. Four patients (8.7%) had a major adverse cardiac event, one patient died, one patient had a myocardial infarction, and two patients had target vessel revascularization at 6 months. The Tristar stent system produces optimal deployment without the need for routine postdilation and results in optimal clinical outcomes.

Impact of various intravascular ultrasound criteria for stent optimization on the six-month angiographic restenosis

We evaluated the impact of different intravascular ultrasound (IVUS) criteria on 6-month angiographic restenosis in 511 patients with 560 lesions. Seven IVUS criteria were evaluated in this study; stent area at lesion segment 1) > or = 100% of distal reference lumen area, 2) > or = 90% of distal reference lumen area, 3) > or = 80% of average reference lumen area, 4) > or = 90% of average reference lumen area, 5) > or = 55% of average reference vessel area, 6) >/= 7 mm(2), and 7) > or = 2). Using the relative measurement (criteria 1-5), the angiographic restenosis rate was not statistically different. However, absolute measurement of stent area > or = 9 mm(2) (criteria 6 and 7) were associated with significantly lower restenosis rate (14.8% vs. 30.9%, P = 0.001, and 13.5% vs. 24.6%, P = 0.006, respectively). In conclusions, using the relative measurement of IVUS criteria, the occurrence of angiographic restenosis might not be predicted. The absolute measurement of IVUS stent area was the predictor of angiographic restenosis.

The contribution of "mechanical" problems to in-stent restenosis: An intravascular ultrasonographic analysis of 1090 consecutive in-stent restenosis lesions

OBJECTIVES

Serial intravascular ultrasonographic (IVUS) studies have shown that in-stent restenosis is the result of intimal hyperplasia (IH). However, routine preintervention IVUS imaging has suggested that many restenotic stents were inadequately deployed. The purpose of this IVUS study was to determine the incidence of mechanical problems contributing to in-stent restenosis (ISR).

METHODS

Between April 1994 and June 2000, 1090 patients with ISR were treated at the Washington Hospital Center. All underwent preintervention IVUS imaging. IVUS measurements included proximal and distal reference lumen areas and diameters; stent, minimum lumen, and IH (stent minus lumen) areas; and IH burden (IH/stent area).

RESULTS

In 49 ISR lesions (4.5%), there were morphologic findings that contributed to the restenosis. These were termed mechanical complications. Examples include (1) missing the lesion (eg, an aorto-ostial stenosis), (2) stent "crush," and (3) having the stent stripped off the balloon during the implantation procedure. Excluding mechanical complications, stent underexpansion was common. In 20% of the ISR cases the stents had a cross-sectional area (CSA) at the site of the lesion <80% of the average reference lumen area. Twenty percent of lesions had a minimum stent area <5.0 mm(2) and an additional 18% had a minimum stent area of 5.0 to 6.0 mm(2). Twenty-four percent of lesions had an IH burden <60%.

CONCLUSION

Mechanical problems related to stent deployment procedures contribute to a significant minority of ISR lesions (approximately 25%).

Coronary intravascular ultrasound: implications for understanding the development and potential regression of atherosclerosis

The incremental value of intravascular ultrasound (IVUS), compared with angiographic analysis of coronary atherosclerosis, originates principally from 2 key features-its tomographic perspective and the ability to image coronary atheroma directly. Whereas angiography depicts the cross-sectional coronary anatomy as a planar silhouette of the lumen, ultrasound directly images the atheroma within the vessel wall, allowing measurement of atheroma size, distribution, and to some extent, composition. Although angiography remains the principal method to assess the extent of coronary atherosclerosis and to guide percutaneous coronary interventions, IVUS is rapidly altering conventional paradigms in the diagnosis and therapy of coronary artery disease. Thus, IVUS has become a vital adjunctive imaging modality for the aggressive coronary interventional cardiologist. As such, ultrasound has earned a role as a viable complementary technique relative to angiography, rather than an alternative to conventional angiographic methods. This article reviews the rationale, technical advantages and limitations, and interpretation of intravascular ultrasonography from the perspective of the general and invasive cardiologist. We emphasize the impact that IVUS studies have had on our understanding of the atherosclerotic coronary artery disease process, because these findings have important implications for all cardiologists. We then review several trials that are currently using intravascular ultrasonography for the study of coronary artery disease regression.

Efficacy of postdeployment balloon dilatation for current generation stents as assessed by intravascular ultrasound

Adjunctive balloon dilatation strategy has been shown to improve optimal stent deployment. As improvements in current stent designs evolve, less adjunctive balloon dilatation may be needed. However, few data currently exist to support this practice. We evaluated 88 native coronary lesions treated with single stent implantation (Nir, Tristar or S670). Serial intravascular ultrasound was performed after successful stent deployment and again after adjunctive balloon dilatation. To investigate further the precise expansion characteristics of the stents, serial volumetric intravascular ultrasound analyses were performed in 40 patients with automated pullback. After adjunctive balloon dilatation, minimal stent area increased significantly, from 6.4 +/- 2.1 to 7.4 +/- 2.2 mm(2) (p <0.001). Volumetric analysis showed a corresponding increase in stent volume index (6.6 +/- 1.8 to 7.5 +/- 2.0 mm(3)/mm, p <0.001). In the analysis of cross sections at 0.5-mm axial intervals, the percentage of cross sections, where stent area was > or =80% of the average reference lumen area, increased from 51% to 78% (p <0.001). Similarly, the percentage of cross sections, where stent area was > or =90% of the average reference lumen area, increased from 29% to 56% (p <0.001) with postdilatation. Postdeployment high- pressure balloon dilatation improved minimal stent area and volumetric expansion throughout the stented segment.

Does stent design affect probability of restenosis? A randomized trial comparing Multilink stents with GFX stents

BACKGROUND

Experimental studies have revealed that stent configuration influences intimal hyperplasia. The purpose of this study was to evaluate clinical outcomes for 2 stent designs in a randomized trial with quantitative coronary angiography (QCA) and intravascular ultrasonography (IVUS).

METHODS

We randomly assigned 100 patients with 107 lesions and symptomatic coronary artery disease to deployment of a Multilink stent (Advanced Cardiovascular Systems, Guidant, Santa Clara, Calif) or a GFX stent (Applied Vascular Engineering, Santa Rosa, Calif) with IVUS guidance. QCA and IVUS studies were performed before and after intervention and at follow-up (4.2 +/- 1.0 months).

RESULTS

There were no significant differences in baseline characteristics and QCA and IVUS parameters before and after intervention between the 2 groups. However, minimal lumen diameter at follow-up was significantly larger in the Multilink group (2.46 +/- 0.59 vs 2.08 +/- 0.79 mm, P <.05). Maximal in-stent intimal hyperplasia was significantly larger in the GFX group (2.9 +/- 1.7 vs 1.8 +/- 1.2 mm(2), P <.01). The restenosis rate differed between the 2 groups (Multilink 4% vs GFX 26%, P =.003). In multiple stepwise logistic regression analysis, the only predictor that significantly correlated with restenosis was stent type (P <.01). The odds ratio for the GFX stent-treated vessels was 18.65 (95% confidence interval 2.10-165.45).

CONCLUSIONS

With deployment of the GFX stent, a thicker neointima develops within the stent. Stent configuration may affect clinical outcomes.

Prognostic value of absolute versus relative measures of the procedural result after successful coronary stenting: importance of vessel size in predicting long-term freedom from target vessel revascularization

BACKGROUND

The procedural result is a major determinant of the incidence of 6-month target vessel revascularization (TVR) after successful coronary stenting. However, the prognostic implications of the different measures of the procedural result or procedural end points have not been directly compared. In this study, we sought to assess and compare the impact of achieving different procedural end points on the long-term (2-year) incidence of TVR.

METHODS AND RESULTS

We studied 234 patients in whom 1 or 2 stents were successfully deployed and ultrasound imaging performed after angiographic optimization. End points included a visually estimated angiographic residual stenosis <10% and ultrasound stent-to-mean reference lumen area > or = 80%. After 2 years, TVR was required in 48 (20.5%) patients. Qualitative predictors of TVR were vein graft lesions, 3-vessel disease, and baseline TIMI flow grade < 3. Quantitatively, reference diameter by quantitative coronary angiography (QCA), final minimum lumen diameter (MLD) by QCA, and in-stent minimum lumen area (MLA) by ultrasound were predictive of TVR. Stent-to-reference ratios were not significantly predictive of TVR. By multivariable analysis, vein graft location and MLA by ultrasound were the only significant predictors of TVR (relative risk, 2.9 [1.5, 5.4] and 0.72 [0.6, 0.9], respectively). Receiver operator curves for MLD by QCA and MLA by ultrasound were similar in predicting TVR. Neither was significantly superior to reference vessel diameter.

CONCLUSIONS

Commonly used angiographic and ultrasound stent-to-reference ratios do not predict the incidence of TVR. Absolute measures of the lumen size (MLA by ultrasound and MLD by QCA) were the most important quantitative predictors of TVR within 2 years. This emphasizes the role of the vessel size as the limiting factor in determining the long-term outcome of coronary stenting.

Six-month angiographic follow-up after intravascular ultrasound-guided stenting of infarct-related artery: comparison with non-infarct-related artery

BACKGROUND

Compared with balloon angioplasty, stenting has been established as an effective treatment modality to reduce restenosis in patients with acute myocardial infarction. However, the immediate results that predict favorable long-term outcomes in the acute infarct stenting are unknown. Therefore, we evaluated long-term outcomes of stenting for infarct-related artery (IRA) lesions by using intravascular ultrasound (IVUS) compared with that of stenting for non-IRA lesions.

METHODS

IVUS-guided coronary stenting was successfully performed in 510 native coronary lesions (105 IRA vs 405 non-IRA). A 6-month follow-up angiogram was performed in 419 (82.2%) lesions: 87 (82.9%) IRA lesions and 332 (82.0%) non-IRA lesions. Coronary stenting on the IRA lesions was successfully performed within 7 to 10 days after onset of infarction in 42 patients and within 12 hours in 45 patients. Results were evaluated by clinical, angiographic, and IVUS methods.

RESULTS

There were no significant differences in clinical and angiographic variables between the two groups. IVUS variables including reference vessel area and minimal stent area were also similar between the two groups. There was no significant difference in angiographic restenosis rate between the two groups in cases of minimal stent area > or = 7 mm(2): 12.8% (6 of 47) in IRA versus 19.1% (33 of 173) in non-IRA lesions (P = .315). However, the angiographic restenosis rate in cases of minimal stent area <7 mm(2) was 50% (20 of 40) in IRA lesions versus 31.5% (50 of 159) in non-IRA lesions (P = .028).

CONCLUSIONS

Angiographic restenosis is significantly higher in stenting for IRA lesions compared with that for non-IRA lesions in cases of minimal stent area < 7 mm(2).

Intensive use of intravascular ultrasound during coronary angioplasty. A six-month campaign

BACKGROUND

Compared to coronary angiography, intravascular ultrasound (IVUS) gives additional information important for the percutaneous transluminal coronary angioplasty (PTCA) procedure, but is time-consuming and may cause complications.

AIM

To evaluate, during a period of intensive use of IVUS, the impact of IVUS on the final decision on balloon/stent diameter, consumption of devices, time-consumption and IVUS-related complications.

METHOD

During a 6-month period, IVUS was contemplated in all PTCA procedures and the reason for not using IVUS was specified. We used CVIS during the first, and Endosonics during the last 3 months, and both periods started with 1 week of hands-on practice. All procedures were to be planned according to an initial quantitative coronary angiography (QCA), and the finally achieved result, material used and complications were registered.

RESULTS

The proportion of IVUS/PTCA was 37% during, 8% 6 months before and 12% 6 months after the study period. Three hundred and twenty-three patients were included in the study (57% of all patients), 199 of them were subjected to IVUS. The indications for PTCA during the study period were stable angina (58%), unstable angina (32%) and acute myocardial infarction (10%). The main reasons for not doing IVUS were use of 6F guiding catheter (13%), urgent procedure (12%) and occluded vessel (11%). Initial QCA detected 253 stenoses in 199 patients and 64 additional stenoses were treated, most of them probably detected by IVUS. QCA systematically underestimated vessel size, particularly in small vessels. There was a non-significant trend to more accurate estimations towards the end of the study in small vessels. Dissection, probably due to IVUS, occurred in two cases (1%). There were no significant differences in the number of devices used in IVUS compared to non-IVUS patients. The procedural time was 24 min longer in IVUS than in non-IVUS cases and more stenoses were treated per procedure in the IVUS group.

CONCLUSION

Coronary angiography often underestimated balloon/stent size but in an unpredictable way, with a substantial proportion of significant stenoses being undetected. IVUS had few serious complications, did not increase device consumption but prolonged procedural time.

Final results of the Can Routine Ultrasound Influence Stent Expansion (CRUISE) study

BACKGROUND

Intravascular ultrasound (IVUS) can assess stent geometry more accurately than angiography. Several studies have demonstrated that the degree of stent expansion as measured by IVUS directly correlated to clinical outcome. However, it is unclear if routine ultrasound guidance of stent implantation improves clinical outcome as compared with angiographic guidance alone.

METHODS AND RESULTS

The CRUISE (Can Routine Ultrasound Influence Stent Expansion) study, a multicenter study IVUS substudy of the Stent Anti-thrombotic Regimen Study, was designed to assess the impact of IVUS on stent deployment in the high-pressure era. Nine centers were prospectively assigned to stent deployment with the use of ultrasound guidance and 7 centers to angiographic guidance alone with documentary (blinded) IVUS at the conclusion of the procedure. A total of 525 patients were enrolled with completed quantitative coronary angiography, quantitative coronary ultrasound, and clinical events adjudicated at 9 months for 499 patients. The IVUS-guided group had a larger minimal lumen diameter (2.9+/-0.4 versus 2.7+/-0. 5 mm, P<0.001) by quantitative coronary angiography and a larger minimal stent area (7.78+/-1.72 versus 7.06+/-2.13 mm(2), P<0.001) by quantitative coronary ultrasound. Target vessel revascularization, defined as clinically driven repeat interventional or surgical therapy of the index vessel at 9 month-follow-up, occurred significantly less frequently in the IVUS-guided group (8.5% versus 15.3%, P<0.05; relative reduction of 44%).

CONCLUSIONS

These data suggest that ultrasound guidance of stent implantation may result in more effective stent expansion compared with angiographic guidance alone.

The role of intravascular ultrasound imaging in vascular brachytherapy

Intracoronary brachytherapy has recently emerged as a new therapy to prevent restenosis. Initial experimental work was achieved in animal models and the results were assessed by histomorphometry. Initial clinical trials used angiography to guide dosimetry and to assess efficacy. Intravascular ultrasound (IVUS) permits tomographic examination of the vessel wall, elucidating the true morphology of the lumen and transmural components, which cannot be investigated on the lumenogram obtained by angiography. This paper reviews the use of IVUS in the clinical studies of brachytherapy conducted to date. IVUS allows clinicians to make a thorough assessment of the remodeling of the vessel and appears to have a major role to play in facilitating understanding of the underlying mechanisms of action in this emerging field. The authors propose that state-of-the-art IVUS techniques should be employed to further knowledge of the mechanisms of action of brachytherapy in atherosclerotic human coronary arteries.

Intravascular ultrasonic predictors of angiographic restenosis after long coronary stenting

The intravascular ultrasound (IVUS) criteria for stent optimization have not been determined in stenting long lesions. We evaluated the predictors of angiographic restenosis and compared it with stent lumen cross-sectional area (CSA) and stent length between short (stent length <20 mm) and long (> or =20 mm) coronary stenting. IVUS-guided coronary stenting was successfully performed in 285 consecutive patients with 304 native coronary lesions. Six-month follow-up angiogram was performed in 236 patients (82.8%) with 246 lesions (80.9%). Results were evaluated using conventional (clinical, angiographic, and IVUS) methods. The overall angiographic restenosis rate was 22.8% (56 of 246 lesions) (short stent 17.6% vs. long stent 32.2%, p = 0.009). Using multivariate logistic regression analysis, the independent predictors of angiographic restenosis were the IVUS stent lumen CSA (odds ratio 1.51, 95% confidence intervals 1.18 to 1.92, p = 0.001) and stent length (odds ratio 0.95, 95% confidence intervals 0.91 to 1.00, p = 0.039). The angiographic restenosis rate was 54.8% for stent lumen CSA of <5.0 mm2 (short stent 37.5% vs. long stent 73.3%, p = 0.049), 27.4% for CSA between 5.0 and 7.0 mm2 (short stent 24.1% vs. long stent 31.7%, p = 0.409), 10.5% for CSA between 7.0 and 9.0 mm2 (short stent 10.0% vs. long stent 12.5%, p = 0.772), and 11.4% for stent lumen CSA of > or =9.0 mm2 (short stent 10.4% vs. long stent 13.3%, p = 0.767) (p = 0.001). Compared with short coronary stenting, long coronary stenting is effective treatment modality to cover long lesions with comparable long-term clinical outcomes in cases of stent lumen CSA of > or =7.0 mm2. Regardless of the stent length, the most important factor determining angiographic restenosis was the IVUS stent lumen CSA in relatively large coronary artery lesions.

Intravascular ultrasonography in the evaluation of results of coronary angioplasty and stenting

The main advantage of intravascular ultrasonography (IVUS) over angiography in assessing the effect of coronary interventions is the ability of IVUS to directly visualize the vessel wall. IVUS often reveals a high residual plaque burden after angiographically successful angioplasty, and this can motivate the operator to use additional, more aggressive measures in an attempt to increase lumen dimensions. Studies using IVUS imaging before and after balloon angioplasty have shown that luminal gain after percutaneous transluminal coronary angioplasty (PTCA) results from a combination of plaque reduction and vessel wall stretch. Minimal luminal area and residual area stenosis after PTCA and stent deployment, as measured by IVUS, have been shown to be predictors of restenosis. IVUS studies have pointed to vessel shrinkage, not intimal hyperplasia, as the main mechanism of restenosis after PTCA. IVUS guidance of stent deployment has often revealed inadequate stent expansion despite optimal results on angiography, leading to high-pressure stent deployment with significant additional luminal gain. Restenosis rates may be lower with IVUS-guided stent deployment.