Left untreated, ventricular tachycardia can trigger a medical emergency known as ventricular fibrillation (V-fib). With V-fib, the heart will not only beat rapidly but also beat erratically.

They reported a total of 51 cases of Adams–Stokes syndrome associated with ventricular fibrillation or prefibrillary ventricular tachycardia ... occurred while Lead V 1 was being taken.