Comparison of the Levels of Cardiac Troponin I in Patients with Duchenne and Becker Muscular Dystrophies to Assess Cardiac Dysfunction

Abstract

Background: Cardiac troponin I (cTnI), uniquely expressed in the myocardium, is a marker for acute myocardial injury. Its clinical significance in Duchenne and Becker muscular dystrophy (DMD and BMD) and its relation to alpha-actinin-3 (ACTN3) genotype as a genetic modifier of cardiomyopathy are still unknown.Methods and Results: Overall, 529 and 131 serum cTnI values of 127 DMD and 47 BMD patients, respectively, were reviewed. cTnI elevation was generally observed in the second decade of life. Both cTnI levels and the proportion of abnormal cTnI levels were significantly higher in DMD patients than in BMD patients (age range: 1< years ≤10 and 10< years ≤18 and 10< years ≤18, respectively). Decreased left ventricular ejection fraction was observed after cTnI elevation in both populations. cTnI levels by age in DMD patients with ACTN3 null genotype tended to increase highly and early.Conclusions: Myocardial injury indicated by cTnI was more common and severe in DMD patients than in BMD patients. cTnI elevation preceding cardiac dysfunction may represent an early phase of cardiomyopathy progression and may be a biomarker for early detection of cardiomyopathy in DMD and BMD patients. The ACTN3 null genotype may be a risk factor for early myocardial injury.