Elevated Plasma Cardiac Troponin T Levels Caused by Skeletal Muscle Damage in Pompe Disease

BACKGROUND: -Elevated plasma cardiac troponin T (cTnT) levels in patients with neuromuscular disorders may erroneously lead to the diagnosis of acute myocardial infarction (AMI) or myocardial injury. METHODS AND RESULTS: -In 122 patients with Pompe disease, the relationship between cTnT, cardiac troponin I (cTnI), creatine kinase (CK), creatine kinase myocardial band (CK-MB) levels and skeletal muscle damage was assessed. ECG and echocardiography were used to evaluate possible cardiac disease. Patients were divided into classic infantile, childhood onset and adult onset patients. cTnT levels were elevated in 82% of patients (median 27 ng/L, normal values <14 ng/L). cTnI levels were normal in all patients, while CK-MB levels were increased in 59% of patients. cTnT levels correlated with CK levels in all three subgroups (P<.001). None of the abnormal ECGs recorded in 21 patients were indicative of AMI, and there were no differences in cTnT levels between patients with and without (n=90) abnormalities on ECG (median 28 ng/L in both groups). The median left ventricular mass index measured with echocardiography was normal in all three subgroups. cTnT mRNA expression was not detectable in controls but was strongly induced in Pompe patients. cTnT protein was identified by mass spectrometry in patient-derived skeletal muscle tissue. CONCLUSIONS: -Elevated plasma cTnT levels in patients with Pompe disease are associated with skeletal muscle damage rather than acute myocardial injury. Increased cTnT levels in Pompe disease and likely other neuromuscular disorders, should be interpreted with caution to avoid unnecessary cardiac interventions.