PET Imaging Agent Predicts Poor Functional Outcomes After Heart Attack

By MedImaging International staff writers
Posted on 16 Jun 2022

Image: New biomarker predicts severity of cardiac remodeling after heart attack (Photo courtesy of Pexels)

Acute myocardial infarction, commonly known as heart attack, is one of the leading causes of death worldwide. After a heart attack, the heart goes through a series of changes at the molecular and cellular level. The fibroblast activation protein (FAP) is overexpressed as these changes occur and can provide useful information about a patient’s prognosis. Now, poor functional outcomes after a heart attack can be predicted with a new PET imaging agent, 68Ga-FAPI-46, according to new research.

A study by researchers at the Hannover School of Medicine (Hannover, Germany) revealed that when correlated with cardiac MRI, 68Ga-FAPI-46 PET is a new specific indicator of active fibrosis and can identify a patient’s chances of recovery. In the study, 35 patients underwent 68Ga-FAPI-46 PET/CT, perfusion SPECT, and cardiac MRI within 11 days after a heart attack. Cardiac FAP-volume was determined by PET imaging and infarct size defined by SPECT imaging. Cardiac MRI showed functional parameters, area of injury and tissue mapping. These datapoints were then compiled to examine potential correlations.

In all patients the FAP-upregulation was significantly larger than both the infarct size and the area of injury as defined by SPECT and cardiac MRI, respectively. A higher extent of myocardial FAP upregulation was predictive of subsequent left ventricular dysfunction. As such, the researchers concluded that fibroblast activation in non-infarcted areas of the heart may contribute to adverse outcomes.

“Molecular PET imaging of the fibroblast activation protein has recently been evaluated in patients after acute myocardial infarction,” said Johanna Diekmann, MD, clinician scientist in the Department of Nuclear Medicine at the Hannover School of Medicine. “In our study, we sought to obtain further insights by correlating FAP-targeted PET imaging with tissue characteristics from cardiac MRI, as well as functional outcome.”

“Myocardial infarction is an important contributor to the development of heart failure, but the early molecular processes involved in the transition from initial injury to heart failure are under-treated,” added Diekmann. “New antifibrotic therapies (such as CAR-T cell therapies) could significantly change future therapy of heart failure. Using FAPI-PET to select patients suitable for therapy would open a new major application for PET in fibrosis and cardiac diseases.”

“FAPI is a very exciting radiotracer that holds great potential for the future of nuclear medicine and molecular imaging,” noted Heather Jacene, Scientific Program chair of the Society of Nuclear Medicine and Molecular Imaging. “68Ga-FAPI-46 PET/CT clearly indicates pro-fibrotic activity after acute myocardial infarction. The predictive value of FAPI-PET for the magnitude of subsequent decline in global cardiac function, if further validated, may be used in the future to help select the most suitable patients for anti-fibrotic therapies which are currently under development. This could ultimately have a powerful impact on cardiovascular medicine.”

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Hannover School of Medicine