An investigation in atrial remodelling and the risk of arrhythmias in endurance athletes

Atrial fibrillation (AF) is the most common sustained heart rhythm problem that increases the chance of stroke and heart failure and currently represents a growing socioeconomic burden in our ageing population. Amongst the established risk factors of age, hypertension and diabetes, exercise is increasingly recognised as a powerful modulator of AF risk. Low and moderate intensity exercise is an important therapy in the prevention and treatment of AF but, at the other end of the spectrum, intense endurance exercise has been associated with a 5-fold increase in AF risk. The reasons for this excess are not known but may relate to the profound atrial remodelling that occurs with endurance athletic training. The rate at which AF occurs in retired elite endurance athletes will be compared with non-athletes who are matched for health status, age and gender. We will assess the extent to which exercise-induced changes in heart shape, function and electrical properties represent a short-term or permanent process. This will be assessed by comparing three groups: (1) young athletes adapting to elite training, (2) middle-aged athletes during end of career detraining, and (3) retired athletes with more than 10 years of competition at national or international level. A group of athletes with arrhythmias will also provide a meaningful comparison group to determine which characteristics are shared amongst groups. To study the changes in heart structure and function we will use the latest echocardiographic and cardiac magnetic resonance imaging techniques. The study is being conducted by a team of researchers at St Vincent's Institute of Medical Research, the South Australian Health and Medical Institute and a research team in Belgium led by A/Professor Andre La Gerche.