Troponin I Levels Correlate with Cardiac MR LGE and Native T1 Values in Duchenne Muscular Dystrophy Cardiomyopathy and Identify Early Disease Progression

Cardiomyopathy is the leading cause of death in Duchenne muscular dystrophy (DMD). Elevated troponin levels are observed in DMD and may vary with disease progression. We studied troponin levels in DMD related to cardiac fibrosis and native T1 measures. This is a prospective, cross-sectional, observational study of 30 DMD subjects measuring native T1 levels and late gadolinium enhancement (LGE) on cardiac MR imaging (CMR) correlated with temporally associated serum troponin I levels. Non-parametric analyses including Spearman correlations and Kruskal-Wallis test were performed between groups. p values resulting from the pair-wise comparisons were adjusted for multiple comparisons using the Sidak method where appropriate. There were 15 DMD subjects with no LGE (age 12 +/- 3 yo; EF% 60 +/- 5) and troponin I level of 0.05 +/- 0.08 ng/ml, of which three had an abnormal troponin level (over 0.04 ng/ml); 7 DMD subjects with mild LGE (age 17 +/- 5 yo, EF% 52 +/- 8) and troponin I level of 0.28 +/- 0.36 ng/ml, of which five had an abnormal troponin level; and 8 DMD subjects with moderate-to-severe LGE (age 16 +/- 6 yo; EF% 54 +/- 8) and troponin I level of 0.11 +/- 0.14 ng/ml, of which four had an abnormal troponin level. Troponin I levels in DMD subjects with mild LGE was significantly increased compared to subjects with no LGE (p = 0.02). There was a statistically significant positive correlation between troponin I levels and MOLLI septal native T1 values (r(2) = 0.173, p = 0.02). Overall, MOLLI lateral native T1 levels were increased with moderate-severe LGE compared to mild and none (p < 0.01). Serum biomarker troponin I levels were increased in DMD subjects with mild LGE and correlated with MOLLI septal native T1 values. Troponin I levels may be a useful minimally invasive outcome marker to monitor myocardial disease progression in DMD cardiomyopathy.