The investigators here propose to investigate the timing and pattern of myocardial fibrosis activity following acute myocardial infarction using hybrid 68Ga-FAPI positron emission tomography and cardiovascular magnetic resonance. The investigators hypothesise that peak fibrosis activity will occur within 2-4 weeks of acute myocardial infarction and will predict subsequent scar formation and cardiac remodelling. Simultaneously, matrix remodelling and fibrosis activity in aortic and coronary atheroma will be assessed enabling the exploration of the presence of unstable atheroma.

Fibrosis is a fundamental process underlying almost all cardiomyopathic conditions. Established fibrosis can be detected by existing imaging techniques including cardiovascular magnetic resonance. However, these techniques are not specific for fibrosis and do not directly measure fibrosis activity or matrix remodelling. This limits the ability to detect early disease and differentiate active from end-stage phenotypes. Fibroblast activation protein is a key factor in fibrogenesis that is expressed in the myocardium following myocardial infarction and in thin-capped fibroatheroma. Radiolabelled fibroblast activation protein inhibitor (68Ga-FAPI) measures in vivo fibrosis activity and matrix remodelling, as supported by preliminary pilot studies. The timing and pattern of myocardial fibrosis activity following acute myocardial infarction will be investigated using hybrid 68Ga-FAPI positron emission tomography. The investigators hypothesise that peak fibrosis activity will occur within 2-4 weeks of acute myocardial infarction and will predict subsequent scar formation and cardiac remodelling. Simultaneously, matrix remodelling and fibrosis activity in aortic and coronary atheroma will also be assessed allowing exploration of the presence of unstable atheroma. This project will enhance understanding of fibrosis activity and matrix remodelling in myocardial infarction and unstable atherosclerotic plaque with potential future application to a broad range of cardiovascular diseases.

Inclusion Criteria:

• specific to cohort;
• aged 50 years or older

Exclusion Criteria:

• Claustrophobia
• Inability to undergo MRI
• eGFR <30ml/min/1.73^m2

Healthy volunteer participants (cohort 1, n=20): those without significant or serious comordibity or known cardiac disease

Participants with acute myocardial infarction (cohorts 2 and 3, n=40): ST-elevation myocardial infarction within 3 weeks of enrollment

Participants with chronic myocardial infarction (n=20): ST-elevation myocardial infarction 24 months or more prior to enrollment