The presence of structural heart disease is often associated with the development of electrical abnormalities of the heart, manifesting as atrial and ventricular arrhythmias. These can occur in those with ischemic and nonischemic cardiomyopathies, congenital heart disease, and various acquired and intrinsic structural abnormalities of the myocardium. Treatment of these arrhythmias generally involves treatment of the underlying disorder first, if possible, such as with surgical or catheter-based intervention. Other therapies, including medical therapy with beta-blockers and anti-arrhythmic agents, pacemakers and implantable cardioverter-defibrillators (ICDs), and ablation may be offered both as prophylactic therapy or if arrhythmias have developed. In some instances, therapy is undertaken regardless of whether there are symptoms. ICDs provide support for those patients at risk for malignant, life-threatening arrhythmias, but appropriate patient and device selection are vital to improve mortality and to limit adverse events.