G.P.25: Low prevalence of skeletal muscle involvement in patients suffering from idiopathic cardiomyopathy

Abstract

Idiopathic cardiomyopathies (ICM) are a group of heterogeneous cardiac diseases that may predispose young patients to sudden cardiac death. They may occur isolated or as a manifestation of a skeletal myopathy, sometimes being the first manifestation of a neuromuscular disease. Involvement of cardiac muscle in patients suffering from ICM may be overlooked, or, sometimes remains poorly defined. We aimed to evaluate the involvement of skeletal muscle in patients diagnosed with ICM. Among a series of 90 patients with ICM we selected 60 patients (sporadic patients presenting before the age of 40, and all familial cases irrespective of the age at the disease onset). We determined serum CK levels, and performed a detailed clinical examination specially focused on the presence of muscle weakness and/or joint retractions. Muscle imaging studies were performed in 49 cases. In 17 cases a genetic analysis was performed using a panel that includes 150 genes involved in familial cardiomyopathies. Results: we have examined 37 patients with dilated CM, 17 with hypertrophic CM, 3 left ventricular noncompaction CM, 2 arrhythmogenic right ventricular dysplasia, and 1 restrictive CM. CK levels were normal in all patients. Mild joint retractions were observed in 10, two of whom also had muscle weakness; two additional patients had isolated muscle weakness. Muscle imaging studies did not show relevant findings except for one patient. Among the patients manifesting muscle weakness and/or joint retractions a pathogenic mutation was identified in 4: LMNA n =1, DES n =1, DSP n =1 and TTN=1. Molecular analysis in 3 patients is currently in course. No mutations were identified in one patient with Achilles tendon retraction. Conclusions: Skeletal muscle involvement in patients with idiopathic cardiomyopathy is rare and in most cases very subtle. A detailed neurological examination may reveal some abnormalities that not always help to reach a final diagnosis.