Randomized Comparison of Coronary Stent Implantation Under Ultrasound or Angiographic Guidance to Reduce Stent Restenosis (OPTICUS Study)
Background— Observational studies in selected patients have shown remarkably low restenosis rates after ultrasound-guided stent implantation. However, it is unknown whether this implantation strategy improves long-term angiographic and clinical outcome in routine clinical practice.
Methods and Results— A total of 550 patients with a symptomatic coronary lesion or silent ischemia were randomly assigned to either ultrasound-guided or angiography-guided implantation of ≤2 tubular stents. The primary end points were angiographic dichotomous restenosis rate, minimal lumen diameter, and percent diameter stenosis after 6 months as determined by quantitative coronary angiography. Secondary end points were the occurrence rates of major adverse cardiac events (death, myocardial infarction, coronary bypass surgery, and repeat percutaneous intervention) after 6 and 12 months of follow-up. At 6 months, repeat angiography revealed no significant differences between the groups with ultrasound- or angiography-guided stent implantation with respect to dichotomous restenosis rate (24.5% versus 22.8%, P=0.68), minimal lumen diameter (1.95±0.72 mm versus 1.91±0.68 mm, P=0.52), and percent diameter stenosis (34.8±20.6% versus 36.8±19.6%, P=0.29), respectively. At 12 months, neither major adverse cardiac events (relative risk, 1.07; 95% CI 0.75 to 1.52; P=0.71) nor repeat percutaneous interventions (relative risk 1.04; 95% CI 0.64 to 1.67; P=0.87) were reduced in the ultrasound-guided group.
Conclusions— This study does not support the routine use of ultrasound guidance for coronary stenting. Angiography-guided optimization of tubular stents can be performed with comparable angiographic and clinical long-term results.
Received March 15, 2001; revision received July 13, 2001; accepted July 16, 2001.
Several randomized studies have demonstrated that stent implantation, as compared with balloon angioplasty, has a preventive effect on restenosis.1,2,3,4 Intravascular ultrasound guidance has been used to optimize stent expansion in order to minimize the risk of subacute stent thrombosis.5 The resulting larger stent dimensions6,7 may, furthermore, contribute to a reduction of restenosis.8,9 To assess the effect of ultrasound guidance on stent restenosis, we conducted a multicenter, randomized study comparing stent implantation under intravascular ultrasound guidance with stent implantation under angiography guidance in intravascular ultrasound–experienced centers.
Patients were eligible for this study if they presented with angina or documented ischemia, no contraindication to antiplatelet therapy, and a lesion length of ≤25 mm to be covered with 1 or 2 stents in an artery with a diameter of ≥2.5 mm. Exclusion criteria were acute angina at rest (Braunwald class III), complete akinesia in the myocardium supplied by the target artery, significant left main lesion, bifurcation lesion, and involvement of a side branch ≥2 mm in diameter with ostial stenosis. The study protocol was approved by the local ethics committee of each center. Written informed consent was obtained from all patients. Patients were randomly assigned to treatment by fax from a central office at Munich University before the start of the procedure, with subrandomization performed for de novo or restenotic lesions.
Patients were treated with IV heparin to achieve an activated clotting time of ≥300 s and with combined antiplatelet therapy, consisting of aspirin (≥100 mg per day) for an indefinite duration and ticlopidine (250 mg BID) started immediately after the procedure and maintained for 4 weeks. Customized stents from 2 companies were implanted (JJIS double spiral bridge, Power Grip, Crown stent [Cordis/Johnson&Johnson], or NIR [Medinol, Boston Scientific Corp]). A minimal balloon inflation pressure of 14 atm was recommended. In patients assigned to ultrasound-guided stent implantation, preinterventional ultrasound assessment was recommended. All ultrasound interrogations were performed with a motorized pullback (0.5 mm/s) after intracoronary injection of nitroglycerin. By ultrasound, the Multicenter Ultrasound Stenting In Coronaries (MUSIC) study criteria,8 and by angiography, a <10% residual diameter stenosis was defined as the target.
Clinical and Angiographic Follow-up
Patients were seen after 14 days and again after 1 month for an interview, check of hematological parameters, and ECG. After 6 (4 to 7) months, these evaluations and the stress test used before the index procedure were repeated, followed by control angiography. If repeat angiography was performed before 4 months for recurrence of symptoms, it served as control angiography only if restenosis was present; otherwise it was repeated after 6 to 7 months. After 12±1 months a final interview and ECG were obtained.
Three angiograms in identical projections were obtained after intracoronary injection of nitroglycerin immediately before and after the intervention and at follow-up. All angiograms were analyzed at the Frankfurt University core laboratory using a validated computer-assisted quantitative angiographic system (CAAS II, Pie Medical BV).10 Analysts were blinded for treatment allocation.
Each ultrasound sequence was reviewed at the Munich University core laboratory by 2 experienced investigators. Standardized planimetry of lumen, stent, and vessel area was performed as described previously.11
The primary end points of the study were the incidence of angiographic restenosis (>50% lumen diameter reduction), minimal lumen diameter, and percent diameter stenosis after 6 months. Secondary end points were major adverse cardiac events during follow-up (death, myocardial infarction, bypass surgery, and repeat coronary intervention) and the fulfillment of ultrasound and angiographic target criteria. Death was defined to include all fatal events, irrespective of cause. Myocardial infarction was defined by new pathological Q waves according to the Minnesota code12 or by an increase of serum creatine kinase to more than twice the normal values with a pathological elevation of myocardial isoenzyme concentration.
Sample Size Calculation and Statistical Analysis
We assumed a restenosis rate of 15% in the ultrasound-guided group and 25% in the angiography-guided group. Using an α of 0.05 and a power of 0.80, a 2-sided χ2 test for the primary end point (restenosis rate) required a sample size of 275 patients in each group, taking into account an estimated loss to follow-up rate of 10%. Categorical data were compared by the χ2 test and Fisher’s exact test. Differences in normally distributed continuous variables were tested by the unpaired Student’s t test. The Mann-Whitney U test was used to compare non-normally distributed continuous variables and categorical data with an ordinal scale. Relative risks with 95% CIs were calculated to compare proportions of clinical events. Event-free survival curves were estimated according to the Kaplan-Meier method and compared by the log-rank test if applicable. If relative risks were not constant over time, the extended Cox proportional hazards model was used to calculate time-dependent relative risks with 95% CIs. All analyses were performed according to the intention-to-treat principle.
Between October 1996 and February 1998, a total of 550 patients were randomized (273 to ultrasound-guided stent implantation and 277 to angiography-guided stent implantation) at 26 centers (Figure 1). There were no differences between the 2 study groups with respect to baseline clinical and angiographic characteristics (Table 1).
Procedural Characteristics and In-Hospital Outcome
Of the 273 patients randomly assigned to ultrasound-guided stenting who underwent revascularization, 21 (7.7%) did not receive the assigned treatment. Two patients underwent elective bypass surgery because the left main stem pathology had not been fully recognized before. In 4 patients, the guidewire did not cross the lesion. In 3 patients, balloon angioplasty alone was successfully performed. Twelve patients crossed over to angiographically guided stenting. The reasons were withdrawal of informed consent to undergo ultrasound assessment in 1, technical failure of the ultrasound catheter in 5, and physician’s preference because of unexpected anatomic findings in 6. Of the remaining 275 patients assigned to angiography-guided stenting, 6 (2.2%) did not receive the assigned treatment: 3 patients were treated with balloon angioplasty alone, and 3 patients crossed over to ultrasound guidance because of angiographically vague morphology.
There were no serious complications due to the ultrasound interrogation. In 4 (2.1%) patients, prolonged spasm after stent implantation, possibly related to the ultrasound investigation, was observed. Maximal balloon diameter and final balloon:artery ratio were larger in the ultrasound-guided group. Maximal balloon pressure and number of guidewires and stents used were similar in both groups. In the ultrasound-guided group, the number of balloons used and volume of contrast medium were higher, and fluoroscopy and total procedural time were longer (Table 2). Of the 252 patients with ultrasound-guided stenting, in 161 (64%) the first balloon was chosen on the basis of the ultrasound assessment, and in 232 (92%) a final documentary ultrasound assessment was performed.
In-hospital clinical outcome did not show significant differences in either study group except for repeat percutaneous interventions which occurred in no patient assigned to ultrasound-guided stenting and in 6 (2.2%) patients assigned to angiography-guided stenting (P=0.030). Table 3
There was no difference in the ultrasound- and angiography-guided groups in baseline angiography (Table 4). Minimal lumen diameter and acute lumen gain were larger in the ultrasound-guided group (3.02 versus 2.91 mm, P=0.006, and 2.07 versus 1.93 mm, P<0.0001, respectively). Residual lumen diameter stenosis was smaller in the ultrasound-guided group (2.8% versus 6.0%, P<0.0001). Of the 536 patients who received a stent, follow-up angiography was performed in 468 (87%). Of these, 457 (85%) angiograms were complete and technically sufficient for analysis. At follow-up, there were no statistically significant differences between the ultrasound-guided and angiography-guided groups with respect to restenosis rate (24.5% versus 22.8%, P=0.68), minimal lumen diameter (1.95 versus 1.91 mm, P=0.52), and percent diameter stenosis (34.8% versus 36.8%, P=0.29). When assessed as per treatment received, these results were not different (restenosis rate 24.2% versus 23.0%, minimal lumen diameter 1.96 versus 1.90 mm, and percent diameter stenosis 34.9% versus 36.8%, all nonsignificant). The cumulative distribution of minimal lumen diameters in both study groups showed substantial overlap (Figure 2).
Angiographic and Ultrasound Success Rates
Optimal stent placement (<10% diameter stenosis) was achieved in 213 (82.2%) patients of the ultrasound-guided group and in 186 (70.7%) of the angiography-guided group (P<0.0001). All 3 ultrasound criteria for optimal stent expansion were reached in 115 (56.1%) patients. The mean stent area in patients assigned to ultrasound guidance was 8.1±2.3 mm2 with a mean proximal and distal reference area of 9.7±3.4 and 8.8±3.2 mm2 respectively.
Clinical Outcome After 1, 6, and 12 Months
Clinical follow-up was complete for 535 (98%) patients after 6 months and for 524 (95%) after 12 months. The incidence of major adverse clinical events was not different in both groups (Table 5). Accordingly, after 6- and 12-month follow-up the Kaplan-Meier curves showed similar event-free curves (Figure 3).
Elective repeat revascularization represented the most frequent clinical event during follow-up. The relative risk among patients assigned to ultrasound-guided stenting was time dependent (P=0.03), with 0.52 (CI, 0.24 to 1.12, P=0.10) before and 1.61 (CI, 0.81 to 3.22, P=0.18) after 4 months (begin of angiographic follow-up). Adjustment for covariables did not change results according to the change-in-estimate criterion.13 Subgroup analysis did not reveal significant differences with respect to target revascularization rate in both groups (Table 6). There were no significant differences between the 2 treatment groups in angina or positive stress-test result at follow-up.
This study failed to show a beneficial effect of the use of intracoronary ultrasound during coronary stenting. Namely, there was no significant difference in the angiographic outcome at 6-months follow-up between both groups, which was the primary end point of the study. This is at variance with what was anticipated on the basis of the findings of previous nonrandomized studies, matched comparisons, and expert opinions.8,9,14,15 In the era before the clinical application of intravascular ultrasound, the restenosis rate after coronary stent implantation varied between 20% and 30%.1,2,16 Observational multicenter studies using ultrasound guidance suggested that restenosis could be reduced to approximately 10%8,9 by optimizing the acute stent result. Despite the use of the same ultrasound criteria for optimizing stent implantation in the present trial and the aforementioned MUSIC and Multi-Link Stent Implanted under Intravascular Ultrasound Guidance (WEST-2) studies, we report a higher restenosis rate (24.5%) in the ultrasound-guided group. By comparison, this may be explained by the higher risk profile of the current study population with inclusion of patients with unstable angina and more complex lesion morphology, factors reported to be predictive of stent restenosis.17,18 However, this does not explain the similar restenosis rate herein reported between the ultrasound- and angiography-guided groups of patients. In our opinion, this is explained by the remarkably acute angiographic results in the angiography-guided group, which were close to those of the ultrasound-guided group. The acute lumen gain of the angiography-guided group of the present study exceeded the gain achieved in previous ultrasound-guided studies.5,8,19,20 A continuous increase in the acute lumen gain has been observed in several randomized and observational studies on coronary stenting.15 This reflects the learning curve of optimizing stent implantation and expansion which was triggered by the concept “the bigger the better”21 and the need for additional imaging modalities5,22 to avoid stent thrombosis and improve long-term outcome.
The results of the present study suggest that optimizing stent implantation by intravascular ultrasound does not confer any beneficial effect on either short- or long-term outcome. But this conclusion only applies to the current population, provided the investigator can reach that level of angiography-guided coronary stenting. The extensive experience with intracoronary ultrasound of the investigators of the present study may have affected the way the stents have been implanted under angiographic guidance. A trend toward a reduced rate of repeat interventions in favor for ultrasound-guided stenting was offset with the beginning of the scheduled angiographic controls. This could be attributed to the “oculostenotic reflex,” which could also be demonstrated by the higher reintervention rate in patients of the BENESTENT II study assigned to control angiography.3 This study did not assess the appropriateness of the criteria of optimal stent expansion. It is conceivable that the use of more strict criteria may lead to even better final results, especially with intracoronary ultrasound. This needs to be explored, considering, however, the potential increase in vessel wall trauma leading to more subsequent tissue formation counteracting the acute angiographic results and clinical outcome.23,24,25
The use of intracoronary ultrasound in this study was associated with the use of more balloon catheters, higher volume of contrast medium, extended x-ray exposition, and prolonged procedure time, which not only will increase costs but also could be potentially harmful. However, some of these drawbacks might be attenuated in the future by use of smaller and combined devices.6,26
In conclusion, this study does not support the routine use of intracoronary ultrasound during stent implantation to improve outcome. Angiography-guided optimization of tubular coronary stents can be performed with comparable angiographic and clinical long-term results. Thus, the additional costs incurred by using intracoronary ultrasound can be saved without an increased patient risk.⇑
H. Mudra (Chairman), P. de Jaegere, K.H. Henneke, A. König, C. Di Mario, A. Zeiher
Study Safety Committee
U. Sigwart (Chairman), B. Meier, N. Reifart
Critical Event Committee
H. Figulla (Chairman), R. Simon, M. Vandormael
A. Zeiher (Chairman), P. Kearney, M.C. Morice, V. Schächinger
K.H. Henneke (Chairman), J. Ge, M. Rothman, D.H. Koschyk
The number of patients enrolled at each center appears in parentheses. Universitätsklinikum Innenstadt, München, Germany: H. Mudra, E. Regar (80); Hospital Clinico San Carlos, Madrid, Spain: C. Macaya, F. Alfonso (55); Herzzentrum, Ludwigshafen, Germany: R. Zahn, J. Senges (40); Sahlgrenska University, Göteborg, Sweden: L. Grip, B. Wennerblom (38); Centro Cuore Columbus, Milan, Italy: C. di Mario, A. Colombo (36); Universitätsklinikum Charité, Berlin, Germany: W. Rutsch, A. Beling (27); Onassis Cardiac Surgery Center, Athens, Greece: V. Voudris (24); Universitätsklinikum Göttingen and Jena, Germany: H. Figulla, M. Ferrari (21); Universitätsklinikum, Köln, Germany: H.W. Höpp, M. Hagemeister (20); L’Institut Cardiovasculaire, Antony, France: M.C. Morice, T. Lefevre (19); Catharina Ziekenhuis, Eindhoven, the Netherlands: J. Bonnier (19); Universitätsklinikum, Frankfurt, Germany: V. Schächinger, A.M. Zeiher (17); Heart and Lung Institute, Utrecht, the Netherlands: P. de Jaegere, F.D. Eefting (16); London Chest Hospital, London, United Kingdom: M. Rothman (16); Clinique Generale St Jean, Bruxelles, Belgium: M.Vandormael (15); Sourasky Medical Center, Tel Aviv, Israel: G. Keren (13); Ospedale San Raffaele, Milan, Italy: I. Sheiban (13); Center for Cardiology, Hamburg, Germany: J. Schofer, C. Kühn (13); Ospedale San Camillo, Rome, Italy: F. Prati (12); Shaare Zedek Medical Center, Jerusalem, Israel: Y. Almagor (10); Universitätsklinikum, Tübingen, Germany: K.R. Karsch, M. Oberhoff (10); Universitätsklinikum, Hamburg, Germany: C.W. Hamm, D. Koschyk (9); Center Cardiologique, Saint-Denis, France: B. Chevalier (8); Medizinische Hochschule, Hannover, Germany: D. Hausmann (8); CHU de Lille, Lille, France: M. Bertrand, E. P. Mc Fadden (6); and Universitätsklinikum, Essen, Germany: R. Erbel, J. Ge (5).
This study was supported by an unrestricted grant from Boston Scientific Corp, Natick, Mass, and by Johnson and Johnson Corp, Warren, NJ.
A list of investigators and centers participating in the OPTICUS Study can be found in the Appendix.
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