VT/VF storm (electrical storm or arrhythmic storm) refers to a state of cardiac electrical instability that is defined by 3 episodes of sustained VT, VF, or appropriate shocks from an ICD within 24 h. Primary prevention ICDS2.2.2-2 ICD placement with the intention of preventing SCD in a patient who has not had sustained VT or SCA but who is at an increased risk for these events. Secondary prevention ICDS2.2.2-2 ICD placement in a patient with prior SCA, sustained VT, or syncope caused by VA. Structural heart disease* This term encompasses IHD, all types of cardiomyopathy, valvular heart disease, and adult congenital heart disease. Arrhythmogenic disease due to a genetic abnormality that results in dysfunction of a cardiac ion channel (eg, long QT syndrome, catecholaminergic polymorphic VT). *The definition of this term may differ across publications. Refer to the entry for the definition used in this document. AV indicates atrioventricular; ICD, implantable cardioverter-defibrillator; IHD, ischemic heart disease; NSVT, nonsustained ventricular tachycardia; SCA, sudden cardiac arrest; SCD, sudden cardiac death; VA, ventricular arrhythmia; VF, ventricular fibrillation; and VT, ventricular tachycardia. CLINICAL STATEMENTS AND GUIDELINES ers, and some antiarrhythmic medications may relieve symptoms of palpitations.S2.2.2-18 PVCs that occur during an exercise test are associ- ated with a higher risk of death.S2.2.2-19 In 1 study, PVCs that occur during recovery are a stronger predictor of death than PVCs occurring only during exercise.S2.2.2-20 However, PVCs are common in trained athletes who have palpitations, in whom there does not appear to be increased risk of death based on studies of small num- bers of athletes, at least in those without other cardio- Complex PVCs may not represent a benign finding in endurance athletes. 