TNNI3 and myotonic dystrophy type 1: Plasma cardiac troponin has emerged as a useful clinical tool to identify patients at increased risk of cardiac events in a range of clinical settings.[15–18] We hypothesised that plasma cardiac troponin I (cTnI) levels may be elevated and act as a biomarker of cardiac involvement in DM1, and thus could prove a useful tool for risk stratification in this group.