The gut-heart axis is a newly evolving field centred around the contribution of the gut microbiome to heart disease. This host-microbiome interaction has been a previously under investigated field in the pathophysiology of heart disease.   The identification of metabolites that require metabolism by gut microbes which then contribute to disease physiology in recent years has contributed to the interest in this field. One metabolite, trimethylamine-N-oxide (TMAO), has been a key molecule of interest as it is known to be associated and potentially causal of heart disease, and importantly, requires the gut microbiome for its production. My research group has investigated the clinical implications of TMAO and other related molecules in heart disease ranging from heart failure to myocardial infarction, and have characterised its properties including response to treatment, ethnic and geographic differences which will be discussed during the symposium. Our work and those of others have advanced understanding in the contribution of the gut microbiome to heart disease (the gut-heart axis).