Acetylcholine (ACh) leads to development of phase 2 reentry and polymorphic ventricular tachycardia (VT) in an experimental model of early repolarization syndrome. Each panel shows simultaneous recordings from one endocardial (Endo) and two epicardial (Epi) sites together with a pseudo-ECG. A: Control; B and C: The combination of verapamil (3 μM) and transient outward current agonist (NS5806, 7 μM) caused an early repolarization pattern to develop in the left ventricular wedge preparation, but no arrhythmogenic substrate. D: The addition of ACh, used to mimic increased vagal tone (ACh, 3 μM), led to the development of phase 2 reentry and polymorphic VT/ ventricular fibrillation. Basic Cycle Length=1000 ms.