Catecholaminergic polymorphic ventricular tachycardia and nonsustained ventricular tachycardia

Ambulatory ECG recordings from a 28-year-old man with exercise-related palpitations. The figure shows two episodes of exercise-related (note sinus tachycardia prior to VT onset) polymorphic VT (arrows). The first episode of VT begins with a VPD on the downstroke of the T wave. The second, briefer episode appears to begin with a later-onset VPD. This patient's arrhythmias were suppressed in response to exercise restriction and nadolol. Genetic testing did not reveal a recognized RYR2 or CASQ2 mutation. Note that the QT interval appears normal for rate.