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J Am Coll Cardiol, 2005; 46:1677-1683, doi:10.1016/j.jacc.2005.06.073
(Published online 7 October 2005). © 2005 by the American College of Cardiology Foundation |
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* Section of Interventional Cardiology-Beth Israel Deaconess Medical Center, Boston, Massachusetts USA
Sarasota Memorial Hospital, Sarasota, Florida USA
Krannert Institute of Cardiology, Indiana University of Medicine, Indianapolis, Indiana USA
Morton Plant Hospital, Clearwater Cardiovascular & Interventional Consultants, Clearwater, Florida USA
|| Montgomery Village, Maryland USA
¶ Wellmont Holston Valley Medical Center, Kingsport, Tennessee USA.
Manuscript received February 28, 2005; revised manuscript received June 17, 2005, accepted June 21, 2005.
* Reprint requests and correspondence: Dr. Joseph P. Carrozza, Jr., Section of Interventional Cardiology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, Massachusetts 02215. (Email: jcarrozz{at}bidmc.harvard.edu).
| Abstract |
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BACKGROUND: Treatment of SVGs with embolic protection reduces adverse cardiac events.
METHODS: We conducted a prospective trial randomizing 631 patients with coronary ischemia and lesions in SVGs to embolic protection with the TriActiv System or control group (Guardwire System [Medtronic AVE, Santa Rosa, California] or Filterwire EX [Boston Scientific Corp., Maple Grove, Minnesota]).
RESULTS: The incidence of major adverse cardiac events at 30 days was 11.2% for the TriActiv group and 10.1% for the control group (relative risk = 1.1%; 95% confidence interval 0.67 to 1.76; p = 0.65; p = 0.02 for non-inferiority). Safety and efficacy end points were similar between groups except that patients randomized to the TriActiv System had more hemorrhagic complications (10.9% vs. 5.4%; p = 0.01).
CONCLUSIONS: The TriActiv System was not inferior to approved embolic protection devices for the treatment of diseased SVGs.
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The SAFER and FIRE studies established that embolic protection with either balloon-occlusion or a filter was the first approach to improve outcome during SVG PCI. These devices were difficult to use, however, and did not prevent adverse events in 8% to 10% of patients. These limitations led to the development of a number of newer balloon-occlusion and filter devices. The multicenter, randomized Protection During Saphenous Vein Graft Intervention to Prevent Distal Embolization (PRIDE) study compared PCI of SVGs with a novel embolic protection system, TriActiv (Kensey Nash Corp., Exton, Pennsylvania), to the Guardwire (Medtronic AVE) and Filterwire EX (Boston Scientific Corp.) devices.
| Methods |
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The PRIDE study. The PRIDE study was a "hybrid" investigation (Fig. 1). At the commencement of the study, one embolic protection device was approved in the U.S. Investigators randomized patients to protection with the TriActiv System versus PCI without embolic protection ("Cohort I"), to demonstrate superiority of the TriActiv System compared with an "unprotected" group. To demonstrate non-inferiority of the TriActiv System compared with a "protected" control group, investigators randomized patients to protection with TriActiv or another protection system approved for use in SVGs ("Cohort II"). Once a site enrolled a patient in Cohort II, future enrollment was limited to Cohort II. Each site enrolled a minimum of two to six "roll-in" patients. The PRIDE study was approved by the institutional review board at each site; all patients provided written informed consent to participate.
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21 years, angina or objective evidence of ischemia, lesion in a SVG (
3.0 mm and
5.0 mm), Thrombolysis In Myocardial Infarction (TIMI) flow grade
0, and ability to provide informed consent. Patients were excluded if any of the following were present: pregnancy, lesion in a native artery or internal mammary graft, distal shoulder of the lesion within 2.0 cm of the distal anastomosis, left ventricular ejection fraction <25%, sequential grafts unless the lesion was >2 cm proximal to the branch point, myocardial infarction (creatine kinase [CK] and CK-MB more than twice the upper limit of normal within 24 h), allergy to aspirin or both clopidogrel and ticlopidine, treatment of
2 SVGs, and co-morbidities limiting life-expectancy to
6 months. Randomization was stratified by intention to administer a glycoprotein IIb/IIIa receptor antagonist before intervention. Patients received aspirin before the procedure and either heparin or bivalirudin during the procedure. After the procedure, aspirin and either clopidogrel or ticlopidine were administered for a minimum of one month. Cardiac enzymes were assessed every 8 h for 24 h. Patients were assessed clinically at 30 days.
Prespecified study end points.
Device success was defined as delivery of the device to the target location with successful operation and removal of the device. Lesion success was defined as the attainment of <50% residual stenosis at the end of the procedure. Procedure success was defined as device success without a major adverse cardiac event (MACE). The primary end point was MACE (either cardiac death, myocardial infarction [any post-procedure CK-MB level
3 x the upper limit of normal], or target lesion revascularization) at 30 days. Pre-specified efficacy and safety end points were device success and final TIMI flow grade, myocardial infarction, in-hospital MACE, stroke at 30 days, and major vascular complications (perforation, hematoma at access site >5 cm, false aneurysm, arteriovenous fistula, retroperitoneal hemorrhage, peripheral ischemia/nerve injury, vascular repair, ultrasound compression, and transfusion).
Study organization (Appendix). Electrocardiograms and angiograms were analyzed by core laboratories blinded to treatment assignment. A blinded events committee adjudicated all events. The overall performance of the study was reviewed by the Data Safety Monitoring Board.
Statistical methods.
All analyses comparing patients in TriActiv Cohort II with those in the control group were made on the basis of intention-to-treat. With an assumed MACE rate of 10%, a sample size of 618 patients would provide 80% power to reject the null hypothesis of inferiority with a
of 6% at the 5% level of significance. Continuous variables were compared with t tests and dichotomous variables by Pearsons chi-square or Fisher exact test if the expected number in any cell was <5. Ordinal variables (e.g., baseline CCS class, sheath size, TIMI flow grade) were tested by the Cochran-Mantel-Haenszel procedure, applying uniform scores to the ordered categories. All analyses were performed using SAS Version 8.2 (SAS Institute, Cary, North Carolina).
| Results |
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| Discussion |
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The PRIDE trial was designed to test two hypotheses: embolic protection with TriActiv is superior to an unprotected control group, and outcomes with TriActiv are not inferior to those with approved distal protection systems. Initially, investigators preferred to enroll in Cohort I. With emerging data demonstrating superiority of embolic protection with the GuardWire System and FilterWire EX, most investigators chose to randomize patients in Cohort II. The limited enrollment in Cohort I underpowered the superiority comparison, precluding any ability to exclude the null hypothesis.
The PRIDE study demonstrated that embolic protection during SVG intervention with the TriActiv System was not inferior to protection with the active control group of either the balloon-occlusion Guardwire System or the Filterwire EX device. The non-inferiority design of Cohort II precludes conclusions regarding the superiority of TriActiv to either the Filterwire EX or Guardwire devices for the prevention of adverse events, although the addition of flush and extraction to balloon occlusion did not appear to confirm additional clinical benefit. Vessels randomized to either TriActiv or the control group had post-treatment rates of TIMI flow grade 3 in excess of 97%, confirming a high degree of efficacy for all three embolic protection devices; however, patients randomized to the TriActiv System were more likely to suffer a hemorrhagic complication, but were not at higher risk of suffering a non-hemorrhagic vascular complication. When stratified according to guiding catheter size, this higher rate of transfusion was observed only in patients randomized to TriActiv and in whom large guiding catheters were used. This finding is best explained by the greater rate of aspiration with larger guiding catheters (200 cc/min with 8-F guiding catheters compared with 125 cc/min with 7-F guiding catheters).
The relatively high incidence of peri-procedural myonecrosis observed in patients treated with any of the three protection devices probably reflects both the complex nature of lesions in the PRIDE trial, and the reality that all three devices have limitations. One of the limitations of the TriActiv System was the longer mean procedure time compared with the active control group. It is possible that the extended time might have contributed to adverse events. To address this problem, the next generation TriActiv FX System, will incorporate a monorail flush catheter, a more precise balloon inflation mechanism, and a guidewire sealing mechanism allowing exchange over the back end of the guidewire. These improvements are expected to reduce total occlusion and procedure times.
Saphenous vein graft degeneration and pretreatment thrombus burden are independent predictors of MACE during SVG intervention (7). The pre-procedure SVG degeneration score was greater in the PRIDE trial than it was in the FIRE trial and lesions in the PRIDE trial also had greater pre-procedural thrombus. Despite greater graft degeneration and thrombus burden, the PRIDE study demonstrated non-inferiority of the TriActiv System compared with approved embolic protection devices. Advances in balloon occlusion systems and filters (e.g., the FilterWire EZ) presumably will improve outcomes with both systems.
Study limitations.
This study has several limitations. Its findings are not generalizable to patients who do not meet entry criteria. The non-inferiority analysis precludes any conclusions of superiority of one group over another. With a pre-specified
of 6%, statistical non-inferiority was achieved; however, this does not establish equivalence in terms of safety or efficacy, because the upper boundary of the 95% confidence interval allows for a relatively large difference within the bounds of non-inferiority. TriActiv could be as much as 29% better or 75% worse than the control device in preventing 30-day MACE. Unlike the SAFER trial, the PRIDE trial allowed enrollment of patients with aorto-ostial lesions and total occlusions. Thus, the outcomes for patients treated with the Guardwire in both trials are not directly comparable. No conclusions can be drawn concerning the comparison of TriActiv System to PCI without protection, because this arm of the trial enrolled too few patients to justify statistical comparisons. Finally, because the choice of Guardwire or FilterWire was left to operator discretion, potential selection bias precludes comparison of either FilterWire to Guardwire, or of either alone to TriActiv.
| APPENDIX. Study organization |
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Principal Investigator. Joseph P. Carrozza, Jr., MD, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
Angiographic Core Laboratory. Jeffrey J. Popma, MD, Brigham and Womens Hospital, Boston, Massachusetts.
ECG Core Laboratory. Alexandra Lansky, Cardiovascular Research Foundation, New York, New York.
Clinical Events Committee. Clifford J. Berger, MD (Chairman), Boston University Medical Center, Boston, Massachusetts.
Data Safety Monitoring Board. Frederick S. Ling, MD (Chairman), University of Rochester, Rochester, New York.
Statistical Analysis. Eugene R. Heyman, PhD, Montgomery Village, Maryland.
Data Management and Analysis. PPD Medical Device, Minneapolis, Minnesota.
Study Monitor. Bailer Research, San Ramon, California.
| Footnotes |
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| References |
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