Muscle fasciculation detected by ECG.

A 79-year-old man presented to hospital with scald burns to the perineum after a syncopal episode while in a hot bathtub. Admission ECG was misdiagnosed as possible ventricular fibrillation with high-frequency irregular waveforms in lead V2 at a rate exceeding 1000 cycles per minute, corresponding to intervening skeletal muscle contractions unrelated to the heart. Follow-up ECG showed full resolution of the irregular waveforms. Muscle fasciculations are a benign cause of ECG artefact and can easily be mistaken for serious cardiac arrhythmias. While most muscle fasciculations detected on ECG are benign, in the correct clinical circumstance these waveforms indicate an underlying neuromuscular disorder. The patient underwent surgical skin grafting with no perioperative cardiac complications and no further syncope in hospital.