Elevation of serum cardiac troponin I in a cross-sectional cohort of asymptomatic subjects with Friedreich ataxia

Background: Friedreich ataxia is an autosomal recessive neurodegenerative disorder characterized by ataxia of all four limbs, dysarthria, areflexia, and cardiomyopathy. At present, baseline values of cardiac troponin I are unknown among Friedreich ataxia subjects.

Methods: In this study, we evaluated baseline plasma cardiac troponin I levels among a cross-sectional cohort of 49 pediatric and adult Friedreich ataxia subjects without active arrhythmia, chest pain or features of acute coronary syndrome at the time of sampling. We also reviewed baseline electrocardiograms from 45 of these subjects.

Results: Troponin I values were elevated above the 99th percentile population cutoff in 46.9% of all subjects, with 16.3% of asymptomatic subjects having levels typically seen during an acute myocardial infarction. In logistic regression models, younger age and an earlier disease onset predicted higher serum cardiac troponin I values. Only weak correlations were seen between cardiac troponin I values and echocardiogram parameters, including ejection fraction. Additionally, 82.2% of subjects also had abnormal baseline electrocardiograms.

Conclusion: The present study demonstrates that both abnormal electrocardiograms and elevated serum cardiac troponin I values may be common baseline characteristics seen in Friedreich ataxia subjects. Further longitudinal studies will allow for a better understanding of the cause and prognostic implications of elevated levels, as well as the clinical utility of serum cardiac troponin I testing in Friedreich ataxia.