Understanding how intensive exercise can lead to abnormal heart rhythms

Understanding atrial fibrillation and right ventricular arrhythmias in the athlete: Role of microRNAs and transcription factors

Exercising regularly is good for heart health, but athletes and people who take part in intensive exercise, such as ultramarathons, can be prone to heart rhythm disturbances such as atrial fibrillation. Dr Alicia D’Souza has previously shown that, in trained hearts, small molecules called microRNAs (miRs) disrupt electrical signals in the part of the heart responsible for regulating contraction of the heart muscle. In this project she will test whether miRs cause electrical instability and arrhythmias in other parts of the trained heart, too. Her initial work has revealed changes in the chambers of the trained heart, specifically the right atrium and right ventricle. Now, in mice, she will study the interactions between miRs and molecules in these chambers after endurance exercise. In particular, she wants to investigate whether miRs increase the amount of collagen in the heart, which can lead to the build-up of scar tissue and affect the ability of the heart to contract. She will also look at whether removing certain miRs in the mice can prevent these changes. Finally, she will test the levels of selected miRs in the blood of highly-trained veteran athletes, which could lead to a test to help doctors find people at risk of abnormal heart rhythms. This research will help us understand the molecular changes that occur after intensive exercise and could lead to the development of specialised miR treatments for arrhythmias.