Sternotomy scars ARVC indicates arrhythmogenic right ventricular cardiomyopathy; CPVT, catecholaminergic polymorphic ventricular tachycardia; IHD, ischemic heart disease; SCA, sudden cardiac arrest; SCD, sudden cardiac death; SIDS, sudden infant death syndrome; and VA, ventricular arrhythmia. Table 6. Continued Component Assessment and Findings Relevant for VA and/or SCD Risk CLINICAL STATEMENTS AND GUIDELINES followed by spontaneous recovery if VT termi- nates, or SCA if VT persists and is not treated promptly. Syncope or SCA may be the first manifestation of structural or electrical heart and some SCA victims have preced- ing sentinel syncope episodes.S4.1-15 Syncope, or its forewarnings of dizziness, lightheadedness, or near-syncope, may constitute a risk factor for SCA and SCD.S4.1-2 The initial evaluation at any age focuses on detection or exclusion of heart disease. Syncope during exercise should prompt thorough evaluation to rule out cardiac causes. Cardiac evaluation with echocardiography, ambulatory monitoring, and exercise testing may be warranted depending on the clinical informa- Cardiac causes of syncope include sustained VT, high-grade atrioventricular block or severe sinus bradycardia or prolonged sinus pauses, supraventricular tachycardia (SVT), malfunction of pacemakers, VA from cardiac channelopathies or structural heart disease syn- dromes, such as hypertrophic cardiomyopathy (HCM) or congenital heart disease.S4.1-3,S4.1-4,S4.1-16 Cardiac channelopathies and HCM are particu- larly important to consider in adolescents and young adults. Arrhythmic causes of syncope are often associated with very short periods of pre- monitory symptoms, or palpitations, and known preexisting heart disease, especially a history of a low LVEF or HF.S4.1-1 Among nonarrhythmic car- diac causes, considerations should include myo- cardial ischemia, severe aortic stenosis, HCM, HF, and prosthetic valve malfunction, pulmonary embolism, medications, and illicit drug use.S4.1-3 4.2. Noninvasive Evaluation 4.2.1. 12-lead ECG and Exercise Testing Recommendations for 12-lead ECG and Exercise Testing Referenced studies that support the recommendations are summarized in Online Data Supplement 2. 