IDE Trial Shows Effectiveness of TherOx's Next-Generation SSO2 Therapy

November 4, 2013—TherOx, Inc. (Irvine, CA) announced results from the company's multicenter pilot study for the company's next-generation system for supersaturated oxygen (SSO₂) therapy as an adjunctive treatment with percutaneous coronary intervention (PCI) to salvage heart muscle in heart attack patients. Shukri David, MD, presented the study results at the TCT 2013: Transcatheter Cardiovascular Therapeutics conference in San Francisco, California.

According to TherOx, SSO₂ therapy is a solution of highly oxygenated saline mixed with the patient's blood delivered through a catheter to the targeted ischemic area of the heart. Used with PCI, SSO₂ therapy is intended to salvage the jeopardized myocardium and thus reduce infarct size, which correlates with improved cardiac function and mortality in heart attack patients.

The company noted that this second-generation system builds on the findings from the AMIHOT II trial of the first-generation system. The new device includes the additional benefits of shortening the treatment time from 90 to 60 minutes and broadening the perfusion treatment area to the entire left coronary system so that no ischemic area goes untreated. The original system only perfused the target artery treated with angioplasty and stenting. SSO₂ therapy is consistent with the 90-minute “door-to-balloon” initiative and supports the current guidelines for interventional cardiology procedures.

In the United States, SSO₂ therapy is delivered by an investigational device, is limited by law to investigational use, and is not for sale or distribution. The study is conducted under a US Food and Drug Administration investigational device exemption (IDE). TherOx's first-generation SSO₂ therapy system has received CE Mark approval.

TherOx stated that the pilot IDE study of the second-generation device enrolled 20 patients at prominent cardiac centers in the United States. The device showed a median 9.6% infarct size measured at 30 days in high-risk patients treated with the second-generation TherOx SSO₂ system. This compares favorably with patients treated with the first-generation SSO₂ system in the AMIHOT II study, who had a 20% infarct size, while control-group patients treated with PCI alone had a 26.5% median infarct size. AMIHOT II was a prospective, multicenter, randomized IDE trial.

In AMIHOT II, TherOx's first-generation SSO₂ therapy system was successful in meeting the safety and effectiveness endpoints. SSO₂ therapy with PCI and stenting demonstrated a relative reduction of 26% in infarct size compared to PCI and stenting alone. In addition to device effectiveness, additional analyses showed a 53% increased likelihood of having a small (< 5% damage of the left ventricle) infarct among SSO₂ therapy patients. The AMIHOT II results were published in Circulation: Cardiovascular Interventions (2009;2:366-375).

“In the successful AMIHOT II study performed with the prior system, SSO₂ therapy was proven to reduce median infarct size by 26%, which is statistically significant. The new SSO₂ system shows promise in producing even better results,” commented Dr. David in TherOx's press release. Dr. David is Section Chief of the Division of Cardiology at Providence Hospital near Detroit, Michigan.