Echocardiographic Ischemic Memory Molecular Imaging for Point-of-Care Detection of Myocardial Ischemia.

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Journal of the American College of Cardiology


cards; cards publication; oregon; portland; Acute Coronary Syndrome; Adult; Aged; Algorithms; Contrast Media; Coronary Angiography; Dose-Response Relationship, Drug; Echocardiography; Female; Healthy Volunteers; Humans; Infusions, Intravenous; Kinetics; Male; Microbubbles; Microcirculation; Middle Aged; Molecular Imaging; Myocardial Infarction; Myocardial Ischemia; Myocardial Perfusion Imaging; Myocardium; Percutaneous Coronary Intervention; Point-of-Care Systems; Young Adult


Background: Noninvasive molecular imaging of recent ischemia can potentially be used to diagnose acute coronary syndrome (ACS) with high accuracy.

Objectives: The authors hypothesized that bedside myocardial contrast echocardiography (MCE) ischemic memory imaging could be achieved with phosphatidylserine microbubbles (MBPS) that are retained in the microcirculation via ischemia-associated endothelial activation.

Methods: A dose-finding study was performed in healthy volunteers (n = 17) to establish optimal MBPS dosing. Stable patients with ACS (n = 30) and confirmed antecedent but resolved myocardial ischemia were studied within 2 hours of coronary angiography and percutaneous coronary intervention (PCI) when indicated. MCE molecular imaging was performed 8 minutes after intravenous administration of MBPS. MCE perfusion imaging was used to assess the status of the postischemic microcirculation.

Results: Based on dose-finding studies, 0.10 or 0.15 mL of MBPS based on body mass was selected. In patients with ACS, all but 2 underwent primary PCI. MCE molecular imaging signal intensity was greater in the postischemic risk area vs remote territory (median [95% CI]: 56 [33-66] vs 8 [2-17] IU; P < 0.001) with a receiver-operating characteristic curve C-statistic of 0.94 to differentiate post-ischemic from remote territory. Molecular imaging signal in the risk area was not related to type of ACS (unstable angina: 3; non-ST-segment elevation myocardial infarction: 14; ST-segment elevation myocardial infarction: 13), peak troponin, time to PCI, post-PCI myocardial perfusion, GRACE (Global Registry of Acute Coronary Events) score, or HEART score.

Conclusions: Molecular imaging with point-of-care echocardiography and MBPS can detect recent but resolved myocardial ischemia. This bedside technique requires only minutes to perform and appears independent of the degree of ischemia. (Ischemic Memory Imaging With Myocardial Contrast Echocardiography; NCT03009266).

Keywords: echocardiography; ischemia; molecular imaging.

Clinical Institute

Cardiovascular (Heart)