Preliminary report of an ongoing phase I/II dose range, safety and efficacy study of iodine-123-phenylpentadecanoic acid for the identification of viable myocardium.

Abstract

An agent that can accurately and cost-effectively identify viable myocardium is needed to select the patients most likely to benefit from myocardial revascularization. Iodine-123-phenylpentadecanoic acid (IPPA) is a synthetic radiolabeled fatty acid that has shown promise in evaluating patients with coronary artery disease (CAD). IPPA has unique metabolic properties that may make it superior to other single-photon agents used for this task. A Phase I/II study is underway to evaluate safety, dose range and efficacy of IPPA in assessing viability and predicting functional recovery after revascularization. Patients between the ages of 21 and 75 with angiographically documented CAD, who were being referred for coronary revascularization, were recruited. The patients were randomized to receive 2, 4 or 6 mCi of IPPA and then underwent sequential SPECT imaging at 4, 12, 20, 28 and 36 min after injection. Radionuclide ventriculography and perfusion imaging were performed before and again 8 wk after revascularization. Myocardial metabolic activity of IPPA was analyzed and compared to the preinjection and postejection fractions. There were no significant adverse effects from the administration of IPPA. Image quality was dose-dependent; the 2-mCi dose was not consistently acceptable for quantitative analysis. These preliminary data show that IPPA is safe and can produce myocardial images of good quality when 4 mCi or more are used. Early results are encouraging but more experience will be needed to define the role of IPPA in identifying myocardial viability.