Skeletal muscle involvement in congenital long QT syndrome.

Skeletal muscle involvement in a genetically confirmed congenital long QT syndrome (LQTS) has not been reported. In a 36-year-old male, intracerebral bleeding from a brainstem cavernoma suddenly occurred. His history was noteworthy for congenital LQTS due to a point mutation in the KVLQT1-gene on chromosome 11. The mutation was also found in his two daughters, his sister, her daughter and his mother. His ECG showed sinusrhythm and a QTc-interval of 0.46 ms. Needle-EMG from the right abductor pollicis, left brachial biceps, left extensor digitorum, and right anterior tibial muscle(s), carried out because muscle involvement had been previously reported in clinically diagnosed congenital LQTS, revealed abnormal spontaneous activity, but otherwise normal motor unit architecture. LQTS, due to a KVLQT1 mutation, may manifest not only in the heart, but subclinically also in the skeletal muscle.