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Historically percutaneous treatment of calcified coronary lesions has been associated with a higher frequency of angiographic complications, restenosis, stent thrombosis, and target lesion revascularization. The Diamondback 360 Coronary Orbital Atherectomy System (OAS) Classic Crown was the first device approved by the Food and Drug Administration indicated specifically to prepare de novo, severely calcified coronary lesions for stent placement. Currently the next generation Diamondback 360 Coronary OAS Micro Crown is under investigation in both the U.S. and Japan in the COAST study.
The COAST study is prospective, single-arm, multi-center, global clinical trial designed to evaluate the performance of the Coronary OAS Micro Crown in treating de novo, severely calcified coronary lesions prior to stent deployment. The Coronary OAS Micro Crown utilizes an eccentrically rotating, 1.25 mm diamond-coated crown which reduces plaque on the vessel wall via centrifugal force to enable successful stent delivery. The primary difference between the Coronary OAS Classic Crown and OAS Micro Crown is the amount and method of off-set mass. Specifically, the OAS Micro Crown has an eccentric crown while the Classic Crown is positioned concentrically on an eccentric bump on the driveshaft. This allows the OAS Micro Crown to rotate at lower speeds while creating an orbit similar to the OAS Classic Crown. In addition, the OAS Micro Crown has a newly designed driveshaft that contains a diamond coated tip bushing to aid the crown in reaching the target lesion. Procedural success, defined as facilitating stent delivery with <50% residual stenosis after Coronary OAS Micro Crown and no in-hospital Major Adverse Cardiac Events (MACE), will be used to evaluate the efficacy of the device. Thirty-day MACE, defined as a composite of cardiac death, target vessel revascularization (TVR), and myocardial infarction (MI), will be used to measure device safety. COAST subjects will be followed for three years. For the first time at CRT 2017, the 1-year MACE data will be presented.
A total of 100 subjects (26 Japan and 74 U.S.) were enrolled in the COAST study. The procedural success rate was 85.0% and the 30-day MACE rate was 15.0%. One-year MACE outcomes are presented in the Table. There were no additional MI or cardiac death events from 31 days to 365 days. By 1-year, nine subjects had a TVR event.
Adequate modification of severely calcified plaque is an important step to achieve successful stent delivery in a historically difficult-to-treat lesion subset. The COAST trial was designed to assess the Coronary OAS Micro Crown in treating severely calcified lesions to facilitate stent deployment.
|Cardiac death (%)||1.0||1.0|
|Myocardial infarction (%)||14.0||14.0|
|Target vessel revascularization (%)||1.0||9.4|
Caution – Investigational Device. Limited by Federal (or United States) law to investigational use.