Abstract
Background/purpose
Bare metal stents (BMS) have similar rates of death and myocardial infarction (MI) compared to drug-eluting stents (DES). DES lower repeat revascularization rates compared to BMS, but may have higher rates of late stent thrombosis (ST) potentially due to impaired endothelialization requiring longer dual anti-platelet therapy (DAPT). OMEGA evaluated a novel BMS designed to have improved deliverability and radiopacity, in comparison to currently available platforms.
Methods/materials
OMEGA was a prospective, multicenter, single-arm study enrolling 328 patients at 37 sites (US and Europe). Patients received the OMEGA stent (bare platinum chromium element stent) for the treatment of de novo native coronary artery lesions (≤ 28 mm long; diameter ≥ 2.25 mm to ≤ 4.50 mm). The primary endpoint was 9-month target lesion failure (TLF: cardiac death, target vessel-related MI, target lesion revascularization [TLR]) compared to a prespecified performance goal (PG) based on prior generation BMS. All major cardiac events were independently adjudicated. DAPT was required for a minimum of 1 month post procedure.
Results
In the OMEGA study, the mean age was 65; 17% had diabetes mellitus. The primary endpoint was met; 9 month TLF rate was 11.5%, and the upper 1-sided 95% confidence bound of 14.79% was less than the prespecified PG of 21.2% (p < 0.0001). One-year event rates were low including a TLF rate of 12.8% and an ST rate of 0.6% at 12 months.
Conclusions
One-year outcomes of OMEGA show low rates of TLF, revascularization and ST. This supports safety and efficacy of the OMEGA BMS for the treatment of coronary artery disease.
Highlights
- •
The OMEGA study evaluated a novel platinum chromium bare metal stent.
- •
OMEGA enrolled 328 patients at 37 sites (US and Europe).
- •
The primary endpoint of 9 month target lesion failure was 11.5%.
- •
One-year event rates were low including an ST rate of 0.6% at 12 months.
1
Introduction
Bare metal stent (BMS) placement in the coronary arteries was introduced to combat two limitations of conventional percutaneous transluminal coronary angioplasty (PTCA): acute vessel closure and late lumen narrowing . Longer-term follow-up demonstrated continued benefit of BMS over PTCA in the treatment of coronary artery disease . Drug-eluting stents (DES) coated with anti-proliferative agents (including the ‘olimus drugs and paclitaxel) have been widely adopted due to their ability to reduce clinical and angiographic restenosis compared with BMS . The benefit of DES lies mainly in lowering the rate of repeat revascularization compared to BMS; most studies have shown that death and myocardial infarction (MI) rates are equivalent in subjects receiving either treatment . The advantages of DES benefit those patients who have the greatest risk of target-vessel revascularization (TVR) such as diabetic patients .
BMS are still used in approximately 15% of patients in the US (and this rate is higher in some other countries) . There are a number of reasons for continued use of BMS including cost of the device and the potential for a shorter mandatory period of DAPT following implantation. Current BMS including Multi-link Driver and Integrity (Medtronic Vascular, Santa Rosa, CA), and Vision (Vision BMS, Abbott Laboratories, Abbott Park, IL, USA), which were approved more than 4 years ago . Innovation in DES stent design and material has progressed in recent years. The developments—including stent strut thickness, type of alloy, and design—have been utilized in the OMEGA stent (Boston Scientific Corporation, Marlborough, MA) which is identical in both material and design to the bare stent component utilized by TAXUS Element (outside of the United States [OUS])/ION (US) and PROMUS Element (OUS)/PROMUS Element Plus Stent Systems). The OMEGA stent is a thin-strut, low-profile and flexible platinum chromium stent with improved acute deliverability, conformability, radial strength, and increased radiopacity making it easy to position and dilate. The OMEGA study evaluated the 9-month and 1-year clinical and postprocedural angiographic performance for the OMEGA bare platinum chromium coronary stent system.
2
Methods
2.1
Device description
The OMEGA Coronary stent (and commercialized REBEL stent; both Boston Scientific Corporation, Marlborough, MA) is a thin-strut (81 μm), balloon-expandable, stent utilizing the same platinum chromium alloy as the PROMUS Element/ION Stent. The OMEGA stent is laser cut from platinum chromium alloy tubing. The REBEL stent is based on the OMEGA stent with additional connectors within the proximal end of the stent and an improved delivery system for increased resistance to compression while maintaining flexibility and deliverability.
2.2
Subject selection, procedure, and follow-up
The OMEGA clinical trial was a prospective, single-arm trial designed to evaluate the safety and effectiveness of the OMEGA stent for the treatment of subjects with a de novo atherosclerotic coronary artery lesion ≤ 28 mm in length and ≥ 2.25 mm to ≤ 4.50 mm in diameter (both by visual estimate). Up to one other non-target lesion, in a non-target vessel, could also have been treated during the index procedure. Key inclusion criteria included: ≥ 18 years of age, symptomatic coronary artery disease or documented silent ischemia, stenosis ≥ 50% to ≤ 100% and a target lesion coverable by 1 stent. Key exclusion criteria included: acute MI, unstable angina, percutaneous coronary intervention (PCI) within the past 12 months, stroke or transient ischemic attack within the last 6 months, lesion location aorto-ostial/left main/saphenous vein graft, extreme tortuosity/angulation/calcification or a side branch ≥ 2.0 mm. Successful predilatation was required for subject enrollment. Patient follow-up occurred at 30 days, 9 months and 1 year.
This study complied with the Declaration of Helsinki, and the research protocol was approved by each locally appointed ethics committee, as applicable. Informed consent was required from all patients prior to performance of any study-related procedures or tests. An independent clinical events committee adjudicated all reported major cardiac events. An independent core laboratory was used to evaluate angiograms (Beth Israel Deaconess Medical Center, Boston, MA). The study is registered at www.clinicaltrials.gov , identifier NCT01419171.
2.3
Endpoints
The primary endpoint was 9-month target lesion failure (TLF) rate, defined as any ischemia-driven revascularization of the target lesion (TLR), MI (Q-wave and non–Q-wave) related to the target vessel, or cardiac death. If it could not be determined with certainty whether the MI was related to the target vessel, it was considered to be related to the target vessel. Other clinical endpoints measured included: individual components of TLF, all-cause death, TVF, and Academic Research Consortium (ARC) -defined stent thrombosis. All major adverse events were adjudicated by a clinical events committee (CEC), and the decisions of the CEC superseded those of the investigational center in the event of a disparity. If the cause of death was unknown it was considered a cardiac death. MI was defined as: 1) Q-Wave MI: development of new pathological Q-waves in 2 or more leads lasting ≥ 0.04 seconds with post-procedure creatine kinase MB (CK) MB levels elevated above normal or 2) non-Q-wave MI: Elevation of post-procedure CK-MB levels to > 3.0 times upper limit of normal (ULN) without new Q-waves. Patients were to have CK/CK-MB levels tested prior to their index procedure. Two CK-MB draws were to be taken within 24 hours post-procedure. Postprocedural angiographic endpoints included in-stent and in-segment percent diameter stenosis, minimum lumen diameter, and acute gain and were adjudicated by a core laboratory.
2.4
Statistical methods
Descriptive statistics were used to describe and summarize the data collected in this clinical study at time points up to 1 year. For continuous variables, mean, standard deviation, and ranges are given. The primary endpoint of the OMEGA trial, 9-month TLF, was tested against a performance goal (PG) generated from a meta-analysis of historical data from trials of BMS plus a 6.0% margin resulting in a PG of 21.2%. Given the PG and the above assumptions, 328 subjects were required.
2
Methods
2.1
Device description
The OMEGA Coronary stent (and commercialized REBEL stent; both Boston Scientific Corporation, Marlborough, MA) is a thin-strut (81 μm), balloon-expandable, stent utilizing the same platinum chromium alloy as the PROMUS Element/ION Stent. The OMEGA stent is laser cut from platinum chromium alloy tubing. The REBEL stent is based on the OMEGA stent with additional connectors within the proximal end of the stent and an improved delivery system for increased resistance to compression while maintaining flexibility and deliverability.
2.2
Subject selection, procedure, and follow-up
The OMEGA clinical trial was a prospective, single-arm trial designed to evaluate the safety and effectiveness of the OMEGA stent for the treatment of subjects with a de novo atherosclerotic coronary artery lesion ≤ 28 mm in length and ≥ 2.25 mm to ≤ 4.50 mm in diameter (both by visual estimate). Up to one other non-target lesion, in a non-target vessel, could also have been treated during the index procedure. Key inclusion criteria included: ≥ 18 years of age, symptomatic coronary artery disease or documented silent ischemia, stenosis ≥ 50% to ≤ 100% and a target lesion coverable by 1 stent. Key exclusion criteria included: acute MI, unstable angina, percutaneous coronary intervention (PCI) within the past 12 months, stroke or transient ischemic attack within the last 6 months, lesion location aorto-ostial/left main/saphenous vein graft, extreme tortuosity/angulation/calcification or a side branch ≥ 2.0 mm. Successful predilatation was required for subject enrollment. Patient follow-up occurred at 30 days, 9 months and 1 year.
This study complied with the Declaration of Helsinki, and the research protocol was approved by each locally appointed ethics committee, as applicable. Informed consent was required from all patients prior to performance of any study-related procedures or tests. An independent clinical events committee adjudicated all reported major cardiac events. An independent core laboratory was used to evaluate angiograms (Beth Israel Deaconess Medical Center, Boston, MA). The study is registered at www.clinicaltrials.gov , identifier NCT01419171.
2.3
Endpoints
The primary endpoint was 9-month target lesion failure (TLF) rate, defined as any ischemia-driven revascularization of the target lesion (TLR), MI (Q-wave and non–Q-wave) related to the target vessel, or cardiac death. If it could not be determined with certainty whether the MI was related to the target vessel, it was considered to be related to the target vessel. Other clinical endpoints measured included: individual components of TLF, all-cause death, TVF, and Academic Research Consortium (ARC) -defined stent thrombosis. All major adverse events were adjudicated by a clinical events committee (CEC), and the decisions of the CEC superseded those of the investigational center in the event of a disparity. If the cause of death was unknown it was considered a cardiac death. MI was defined as: 1) Q-Wave MI: development of new pathological Q-waves in 2 or more leads lasting ≥ 0.04 seconds with post-procedure creatine kinase MB (CK) MB levels elevated above normal or 2) non-Q-wave MI: Elevation of post-procedure CK-MB levels to > 3.0 times upper limit of normal (ULN) without new Q-waves. Patients were to have CK/CK-MB levels tested prior to their index procedure. Two CK-MB draws were to be taken within 24 hours post-procedure. Postprocedural angiographic endpoints included in-stent and in-segment percent diameter stenosis, minimum lumen diameter, and acute gain and were adjudicated by a core laboratory.
2.4
Statistical methods
Descriptive statistics were used to describe and summarize the data collected in this clinical study at time points up to 1 year. For continuous variables, mean, standard deviation, and ranges are given. The primary endpoint of the OMEGA trial, 9-month TLF, was tested against a performance goal (PG) generated from a meta-analysis of historical data from trials of BMS plus a 6.0% margin resulting in a PG of 21.2%. Given the PG and the above assumptions, 328 subjects were required.
3
Results
3.1
Patient, lesion and procedural characteristics
The OMEGA study enrolled 328 patients at 37 investigative sites (22 sites in the US and 15 sites in the EU: Belgium, France, Germany, Latvia, Netherlands, and Spain) from October 2011 to January 2013. Clinical follow-up was available in 98.2% (322/328) of patients at 9 months and in 97.6% (320/328) at 12 months ( Fig. 1 ). Baseline patient, lesion and procedural characteristics are listed in Tables 1, 2 and 3 . Patients were predominantly male (68%) with a history of medically treated hyperlipidemia (71%) and hypertension (75%). Medically treated diabetic subjects accounted for 17% of subjects.
| Characteristic | N = 328 patients |
|---|---|
| Male | 67.7% (222/328) |
| Age, years | 65.5 ± 11.2 (328) |
| Current smoker | 28.2% (90/319) |
| Previous smoker | 37.9% (121/319) |
| Medically treated diabetes | 17.4% (57/328) |
| Insulin-dependent | 5.5% (18/328) |
| Hyperlipidemia | 70.8% (230/325) |
| Hypertension | 75.0% (243/324) |
| Stable angina | 55.5% (182/328) |
| Chronic heart failure | 6.4% (21/327) |
| Prior PCI | 29.1% (95/326) |
| Prior MI | 29.6% (96/324) |
| History of renal disease | 4.3% (14/326) |
| History of PVD | 6.4% (21/326) |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
