P409 MYOCARDITIS OR RHABDOMYOLYSIS WITH MYOCYTE NECROSIS?

Abstract

Abstract Rhabdomyolysis is a clinical syndrome involving skeletal muscle tissue characterized by muscle weakness, myalgias and increased creatine phosphokinase (CPK) levels, usually 5 times up the normal limit. During rhabdomyolysis troponin (TNI) may be released due to mismatch between oxygen supply and demand, cytokine and endotoxin toxicity, presence of heterophile antibodies that cause false positive results and cross–reactivity between TNI isoforms produced by skeletal muscle and TNI isoforms produced by cardiac muscle. The triggering causes are multiple and include viral infections and genetic pathologies involving skeletal muscles. Genetic mutations of filamin C can cause myofibrillar myopathies, a heterogeneous group of neuromuscular disorders characterized by myopathy involving proximal and distal muscles that often occur in adulthood and may be associated with cardiomyopathies. Genetic mutations of filamin C can also be found in healthy adults because some variants have a subclinical expression. Case Report A 34 years old man came to the Emergency Department (ED) with fever, diarrhoea, asthenia and anuria. His past medical history was characterized by 4 episodes of myocarditis (TNI value increased up to 21 ng/dl, reduced left ventricular ejection fraction to 40%) all occurring in conjunction with acute gastroenteritis. The genetic analysis, performed six months before, showed a heterozygous mutation of the gene coding for filamin C. Blood tests performed in ED showed an increase in CRP values (4.8mg/dl), in transaminases values and a modest increase in troponin values (0.96ng/dl) without electrocardiographic and echocardiographic abnormalities (ejection fraction was preserved). He was admitted to Emergency Cardiology Department with a diagnosis of myocarditis. The CPK value resulted to be 22.503 U/l (n.v. 60 –190 U/l). Cardiac MRI underlined no signs of acute myocarditis. The patient, treated with intravenous fluid therapy, after one week showed clinical improvement and normalization of CPK and TNI values. Conclusions in the present case the acute gastrointestinal event was the trigger of rhabdomyolysis and not of an acute myocarditis as initially erroneously interpreted, in a patient carrying a genetic mutation predisposing to myopathies. Follow–up will evaluate whether and to what extent the genetic abnormality will lead to the development of myopathy and/or cardiomyopathy.