Shelley Wood

November 06, 2013

SAN FRANCISCO, CA — Back in March 2009, an FDA advisory panel voted nine to five against recommending approval of a device designed to deliver supersaturated oxygen (SSO2) therapy after PCI with the aim of reducing final infarct size. The FDA, in turn, sent the device maker, Therox, back out to fetch more data on its Aqueous Oxygen System.

Last week at TCT 2013 , investigators were back with new data on a next-generation, "optimized" system that they say offers safety and efficacy advantages over the original system.

According to Dr Shukri David (Providence Hospital, Southfield, MI) these latest pilot results "warrant a randomized trial of safety and effectiveness in high-risk STEMI patients."

As previously reported by heartwire , the first AMIHOT study failed to show a difference in infarct size or clinical events at 30 days for the trial population as a whole but hinted that a subgroup of patients might benefit. The subsequent AMIHOT II trial zeroed in on this subgroup: patients with large infarcts after acute MI who ended up undergoing PCI within six hours of symptoms. In AMIHOT II, infarct size measured by single-photon-emission computed-tomography (SPECT) imaging at 14 days was 6.5% smaller in patients who received supersaturated blood than patients who received standard therapy. There were, however, signals that major adverse cardiac events (MACE) trended higher in the supersaturated blood group.

According to David, the optimized SSO2 Therapy uses a smaller guide and infusion catheter, uses a point of infusion that is further from the PCI injury zone, and infuses the entire left coronary system. Duration of therapy is also shorter than that used in AMIHOT II (60 min vs 90 min).

In results David presented last week, 20 patients with anterior STEMI of less than six hours' duration underwent PCI with stenting of the new proximal or mid-LAD target lesion. SSO2 was delivered safely immediately after PCI in all 20 patients, Two patients had an asymptomatic intrastent thrombosis that was treated successfully on the spot.

At 30 days, two reinfarctions and one target lesion revascularization had occurred. Infarct size on MRI, defined as percent of the left ventricle, was just 9.6%. That's compared with 30-day infarct sizes in AMIHOT I and II, combined, of 18.5% in the SSO2-treated patients and 25.0% in the untreated patients.

The results, said David suggested that "optimized SSO2 offers a potentially safer, simpler, and more effective means to reduce infarct size for high-risk anterior MI."

Whether reductions in infarct size actually contribute to improved clinical outcomes—and whether the FDA wants to see hard clinical outcomes before approving the device—remain to be seen.

David disclosed serving on the advisory board for Boston Scientific and St Jude Medical.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.