CSI's ORBIT II Study of Coronary Atherectomy Meets Primary Endpoints

March 11, 2013—Cardiovascular Systems, Inc. (CSI; St. Paul, MN), announced the presentation of pivotal 30-day data from its ORBIT II study of severely calcified coronary lesions at the 62nd annual scientific session of the American College of Cardiology in San Francisco, California. Jeffrey Chambers, MD, of Metropolitan Heart and Vascular Institute in Minneapolis, Minnesota, delivered the presentation.

ORBIT II is evaluating the safety and effectiveness of orbital atherectomy technology in treating a problematic subset of patients with severely calcified coronary lesions. The study, conducted under an investigational device exemption, is being used to seek approval for treating these lesions. CSI completed ORBIT II enrollment of 443 patients at 49 medical centers in the United States in November 2012.

According to CSI's press release, the study demonstrated that the company's orbital atherectomy technology produced clinical outcomes that exceeded the trial's two primary endpoints by a significant margin within a highly challenging patient population. In the study, 100% of patients had severe coronary calcification. The company noted that moderate to severe arterial calcium is estimated to be present in approximately 40% of patients undergoing a percutaneous coronary intervention.

As summarized in the company's announcement, Dr. Chambers presented the following 30-day data of patient outcomes, which exceeded the study's primary safety and efficacy endpoint targets by a significant margin.

The overall freedom from major adverse cardiac events was 89.8%, with a 9.7% rate of myocardial infarction (MI; non-Q-wave, 8.8%; Q-wave, .9%); a .7% rate of target vessel revascularization; a .7% rate of target lesion revascularization; and a .2% rate of cardiac death.

The overall procedural success rate was 89.1%, including a 97.7% rate of successful stent delivery. There was a 98.6% rate of cases resulting in residual stenosis of less than 50%. The in-hospital major adverse cardiac event rate was 9.5% with an MI rate of 9.3% (non-Q-wave, 8.6%; Q-wave, .7%) and a target vessel revascularization rate of .7%. The rate of cardiac death was .2%.

“While treatment of severely calcified coronary arteries remains a challenge, 30-day ORBIT II results show that study endpoints were met by a significant margin and demonstrate that CSI's orbital atherectomy system may be a viable treatment option,” commented Dr. Chambers in CSI's press release. “ORBIT II represents the only study to date of this hard-to-treat patient population. Past studies haven't attempted to treat severely calcified lesions, due to the challenge of meeting endpoints and overall treatment success.”

The company's orbital atherectomy technology is currently used to treat calcified and fibrotic plaque in arterial vessels throughout the leg. In August 2007, the US Food and Drug Administration (FDA) granted 510(k) clearance for the use of the Diamondback orbital atherectomy system to treat peripheral arterial disease.

The ORBIT II investigational device exemption clinical trial is evaluating the safety and effectiveness of its orbital technology in treating coronary arteries. The coronary system is limited by federal law to investigational use and is currently not commercially available in the United States. CSI expects to submit its premarket approval application to the FDA by the end of March.