Population Subgroups and Risk Prediction e282 3. Mechanisms of VA e283 3.1. Cellular Mechanisms and Substrates e283 3.2. Automaticity e283 3.3. Triggered Activity e283 3.4. Reentry e284 4. General Evaluation of Patients With Documented or Suspected VA e284 4.1. History and Physical Examination e284 4.2. Noninvasive Evaluation e286 4.2.1. 12-lead ECG and Exercise Testing e286 4.2.2. Ambulatory Electrocardiography e286 4.2.3. Implanted Cardiac Monitors e287 4.2.4. Noninvasive Cardiac Imaging e287 4.2.5. Biomarkers e288 4.2.6. Genetic Considerations in Arrhythmia Syndromes e288 4.3. Invasive Testing e289 4.3.1. Invasive Cardiac Imaging: Cardiac Catheterization or CT Angiography e289 4.3.2. Electrophysiological Study for VA e289 5. Therapies for Treatment or Prevention of VA e290 5.1. Medication Therapy e290 5.1.1. Medications With Prominent Sodium Channel Blockade e290 5.1.2. Beta Blockers e293 5.1.3. Amiodarone and Sotalol e293 5.1.4. Calcium Channel Blockers e294 5.1.5. Nonantiarrhythmic Medications and Therapies e294 5.2. Preventing SCD With HF Medications e295 5.3. Defibrillators for Treatment of VA and SCD e295 5.4. Catheter Ablation e295 5.4.1. General Considerations e295 5.4.2. VA in Patients With No Apparent Structural Heart Disease e296 5.4.3. Scar-Related VT e296 5.5. Surgery and Revascularization Procedures in Patients With Ischemic Heart Disease e296 5.5.1. Surgery for Arrhythmia Management e297 5.6. Autonomic Modulation e297 6. Acute Management of Specific VA e297 7. Ongoing Management of VA and SCD Risk Related to Specific Disease States e301 7.1. Ischemic Heart Disease e301 7.1.1. Secondary Prevention of SCD in Patients With Ischemic Heart Disease e301 7.1.2. Primary Prevention of SCD in Patients With Ischemic Heart Disease e304 7.1.3. Treatment and Prevention of Recurrent VA in Patients With Ischemic Heart Disease e306 7.2. Nonischemic Cardiomyopathy e308 7.2.1. Secondary Prevention of SCD in Patients With NICM e308 7.2.2. Primary Prevention of SCD in Patients With NICM e309 7.2.3. Treatment of Recurrent VA in Patients With NICM e310 7.3. 