Molecular contrast agents for post-infarct cardiac remodelling: a contemporary review

Myocardial infarction (MI) is a leading cause of mortality, affecting 3.8% of the global population under 60 years of age, and 9.5% over 60 years. Adverse post-MI remodelling is the main contributor to heart failure, conferring a three- to six-fold increase in risk of premature death. Current imaging modalities, such as nuclear imaging and magnetic resonance imaging, provide structural and functional information of the heart and identify extracellular expansion for indirect estimation of infarct size. However, they do not characterize the exact biological mechanisms involved, nor the staging of disease progression. Molecular imaging aims to visualize the underlying processes of remodelling at a molecular and cellular level, aiding more accurate prognosis and targeted treatment. Molecular tracers, such as radioisotopes and paramagnetic nanoparticles, are modified to adhere to specific molecules or cells involved in inflammation, angiogenesis, and scar formation, which can be visualized and quantitatively assessed using positron-emission tomography and magnetic resonance imaging. This article provides an overview of the pathophysiology of adverse remodelling, the latest molecular contrast agents under development, and future directions for integration into clinical practice.