Acute Myocardial Infarction With Hyperoxemic Therapy - AMIHOT
The goal of the trial was to evaluate the safety and efficacy of hyperoxemic therapy to attenuate reperfusion injury and improve recovery of left ventricular function after primary percutaneous coronary intervention (PCI).
Patients Enrolled: 269
Mean Follow Up: 30 days
Mean Patient Age: Mean age, 60 years
Acute anterior or inferior MI undergoing primary PCI <24 hours from symptom onset
Cardiogenic shock, need for intra-aortic balloon pump, severe pulmonary disease, coronary artery bypass grafting within 1 month, severe valvular disease, initial TIMI grade 3 flow prior to stenting, TIMI flow grade <2 after stenting, or significant left main disease
Efficacy: 1) wall motion score index (measured by serial contrast echocardiography), 2) infarct size at 14 days (measured by 99m Tc-sestamibi SPECT imaging), and 3) ST-segment resolution (using continuous ST monitoring)
Safety: MACE at 30 days
Patients with acute anterior or inferior myocardial infarction (MI) undergoing primary PCI (<24 hours from symptom onset) were randomized following successful PCI to either hyperoxemic reperfusion (treatment group; n = 134) or normoxemic blood autoperfusion (control group; n = 135).
In the hyperoxemic group, intracoronary hyperoxemic reperfusion was performed for 90 minutes using the TherOx® AO System (TherOx Inc., Irvine, California). Hyperoxemic therapy was performed by mixing 3 ml of aqueous oxygen (AO) with 70 ml/min of patient blood. The mixture was subsequently infused through a catheter in the infarct artery in the region of stent placement. All patients received stent implantation.
Anterior MI was present in 58% of patients overall, with a median time from symptom onset to reperfusion of 248 minutes in the control arm and 260 minutes in the AO arm.
In the hyperoxemic therapy arm, 117 (87%) received the full 90-minute infusion. Hyperoxemic reperfusion was generally well tolerated, and no hemodynamic or electrical instability was observed during AO infusion. There was one case of stent thrombosis that developed during the AO infusion. There was no difference in the use of glycoprotein IIb/IIIa inhibitors (84% in the control and 90% in the AO arm) or in final TIMI grade 3 flow (92% and 96%, respectively).
Major adverse cardiac events at 30 days was similar in both arms (5.2% for control vs. 6.7% for AO, p = NS).
There was no difference in the sum of ST resolution area under the curve, infarct size on SPECT (13% in the control group vs. 11% in the AO group, p = 0.30), or in change in regional wall motion score index (RWMSI) on echocardiography at 3 months (-0.57 in control group vs. -0.62 in AO group, p = 0.24). In a post-hoc analysis of the subgroup of patients with anterior MI reperfused within 6 hours, change in RWMSI was greater in the AO group (-0.54 for control vs. -0.75 for AO, p = 0.03) and infarct size was smaller in the AO group (23% for control vs. 9% for AO, p = 0.04).
Among patients with acute MI undergoing primary PCI with stenting, use of hyperoxemic therapy was not associated with significant differences in ST resolution, regional wall motion changes, or infarct size compared with control.
While the overall results of the trial were negative, an interesting subgroup was identified: patients with anterior MI who were reperfused within 6 hours. However, these results should be interpreted cautiously considering the overall negative results of the trial. The median time from symptom onset to treatment overall in the study was relatively long compared with most randomized trials in acute MI. Patients presenting late after symptom onset have shown limited benefits with many reperfusion therapies.
O'Neill WW, Martin JL, Dixon SR, et al. Acute Myocardial Infarction With Hyperoxemic Therapy (AMIHOT): a prospective, randomized trial of intracoronary hyperoxemic reperfusion after percutaneous coronary intervention. J Am Coll Cardiol 2007;50:397-405.
Presented by Dr. William W. O'Neill at the American College of Cardiology Annual Scientific Session, March 2004.
Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Vascular Medicine, Interventions and Coronary Artery Disease, Interventions and Imaging, Interventions and Vascular Medicine, Computed Tomography, Echocardiography/Ultrasound, Nuclear Imaging
Keywords: Coronary Artery Disease, Reperfusion Injury, Inferior Wall Myocardial Infarction, Ventricular Function, Left, Thrombosis, Tomography, Emission-Computed, Single-Photon, Oxygen, Fluorocarbons, Stents, Echocardiography, Percutaneous Coronary Intervention
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