Much of the public was introduced to the implantable cardioverterdefibrillator (ICD) when Vice President Cheney, a survivor of four heart attacks, received the device in 2001. Although ICDs were initially limited to patients with previous cardiac arrests or arrhythmias, more recent studies have demonstrated that ICDs can prevent sudden cardiac death in patients who have not had a cardiac arrest, but are at greater risk for one (for example, those with congestive heart failure and reduced cardiac function). This Issue Brief summarizes studies that analyze health outcomes, costs, and quality of life for patients-at-risk who receive ICDs in real-life settings.