Prognostic role of exercise intensity in familial Filamin C truncating variants

Background: Truncating variants in the Filamin C (FLNCtv) gene are causative of highly arrhythmogenic cardiomyopathies. Guidelines remain controversial concerning competitive and high-intensity sports for FLNCtv carriers. Indeed, the impact of high-intensity exercise on individuals carrying these variants remains poorly understood. Methods and results: This retrospective study analysed 45 probands and relatives carrying FLNCtv, collecting data on previous physical activity. Over a mean follow-up of 4.9±0.6 years, 9 individuals (20%) experienced life-threatening arrhythmias (LTA). No significant association was found between history of higher-intensity exercise and increased LTA risk (OR 1.442; 95% CI 0.321 to 6.467; p=0.633), left ventricular systolic dysfunction (OR 0.505; 95% CI 0.143 to 1.791; p=0.290) or right ventricular dysfunction (OR 3.333; 95% CI 0.263 to 42.212; p=0.353). However, three phenotype-positive subjects (7%), mostly with dilated cardiomyopathy, experienced LTA during intense exercise. Conclusions: Over a mean follow-up of 5 years, high-intensity exercise did not appear to be associated with an increased risk of LTA or structural cardiac disease in FLNCtv carriers. However, we report LTA in already affected subjects during intense exercise. These findings indicate that further investigations may lead to a re-evaluation of exercise recommendations for phenotype-negative carriers and highlight the importance of larger population-based studies on this topic.