The objective of this study is to evaluate acute changes of cardiac troponin (and other cardiac biomarkers) and mid-term biovariability in patients with cardiomyopathy associated with chronic skeletal muscle disease. The specific aims of the study are:

Firstly, to evaluate the feasibility of the ESC 0/1 hour protocol for rule-in and rule-out of a non-ST-segment elevation acute coronary syndrome (NSTE-ACS).

Secondly, a) to determine reference change values (RCV) to characterize physiological biovariability, b) to differentiate acute from chronic high-sensitivity cardiac troponin T (hs-cTnT) elevations.

In patients with skeletal muscle dystrophy, cardiac involvement is one of the limiting factors regarding mortality. Early detection of a dystrophy-associated cardiomyopathy is important, as heart failure therapy can slow adverse cardiac remodeling and alleviate heart failure symptoms. Cardiac biomarkers, especially high-sensitivity cardiac Troponin T (hs-cTnT) and to a lesser extent, high-sensitivity cardiac Troponin I (hs-cTnI), are chronically elevated in diseases with underlying structural heart disease. However, there is no reliable data on whether changes in the concentration of cardiac Troponin T or I are suitable for monitoring the cardiac disease progression. This can lead to delayed diagnosis and treatment of a relevant deterioration of the disease or even acute heart muscle damage in the context of acute myocardial infarction, pulmonary embolism, and myocarditis. Due to insufficient clinical data, the feasibility and safety of the ESC 0/1-hour protocol according to the ESC guidelines for the diagnosis of acute myocardial infarction in this patient population are uncertain. Furthermore, it is necessary to determine the normal biovariability of high-sensitivity cardiac Troponin T (hs-cTnT) and high-sensitivity cardiac Troponin I (hs-cTnI) to differentiate physiological concentration fluctuations of these cardiac biomarkers in this patient population from changes that represent an improvement or deterioration of heart function. Routine blood samples that will be collected at presentation, a second blood sample for study purposes will be collected after 1 hour for the first index visit. On the routine follow-up visit, 20 ml of blood will be collected for storage in addition to the routine blood test. Blood samples will be obtained by standard venous blood sampling. If venipuncture is unsuccessful or considered harmful by the patient and a suitable peripheral venous catheter is available, the venous catheter may be used for blood sampling to minimize damage. Assessment of parameters includes demographics and clinical characteristics (symptoms, history, medication, vital signs, risk scores etc.) and laboratory values with special focus on findings related to myocardial injury as indicated by high sensitivity cardiac troponin T (hs-cTnT) and hs-cTnI. Moreover, the laboratory panel comprises other cardiac biomarkers, electrolytes, renal (creatine, glomerular filtration rate) and liver function (GOT, GPT, LDH), C-reactive protein, D-dimer etc.

Inclusion Criteria:

• Written informed consent
• Diagnosed muscular dystrophy
• Patients >18 years of age

Exclusion Criteria:

• Patients with poor venous status
• Hemodialysis
• Lack of capacity to provide informed consent or refusal

All consecutive patients with cardiomyopathy associated with chronic skeletal muscle disease presenting at Heidelberg University Hospital in the cardiomyopathy outpatients' clinic during a time period of 12 months are eligible for study inclusion.