Molecular imaging of atrial myopathy: Towards early AF detection and non-invasive disease management

Atrial fibrillation (AF) is a common arrhythmia that can lead to stroke. The diseased muscle tissue of the atria develops atrial fibrosis, inflammation, thrombosis and subsequent strokes, resulting in significant morbidity and mortality. Current diagnostic and evaluation paradigms for clinical AF focus on identifying functional and morphological abnormalities of the left atria by echocardiography. Notably, the development of atrial substrate that marks AF likely occurs for years before the manifestation of AF onset, meaning that the functional and morphometrical aberrations are end-stage features, representing a stable state of an already-compromised tissue. There is no existing 'gold standard' measure to identify the early atrial muscle disease and characterization of the atrial substrate is inadequate. In fact, sub-clinical identification of atrial myopathy is not undertaken in clinical practice because there is no robust screening method. Development of molecular imaging probes for detection of atrial muscle disease might enable early detection and staging of AF, ultimately leading to improved treatment outcome. In this review, we discuss possible molecular imaging targets that may enable early diagnosis of cardiovascular disease, with focus on novel insights, challenges and opportunities for sub-clinical imaging of atrial myopathy and AF.