Facts about SCA Sudden cardiac arrest (SCA) is the sudden, abrupt loss of heart function generally caused by a rapid, irregular rhythm of the ventricles (ventricular tachycardia [VT] or ventricular fibrillation [VF]). These arrhythmias result in quivering ventricles that cannot pump blood to the body. Loss of consciousness and pulse follow within seconds. In approximately 94-95% of cases, SCA is fatal leading to sudden cardiac death or SCD.3 SCA, an electrical conduction problem, is not the same as a heart attack (myocardial infarction [MI]) which is caused by a blocked vessel leading to loss of blood supply to a portion of the heart muscle. Who is at risk for SCA? Heart rhythm disorders can affect anyone, regardless of age, gender, physical fitness, etc. Post myocardial patients with low ejection fraction are at a particularly high risk for lethal arrhythmias - even if they are being optimally managed with ace-inhibitors and beta blocker therapy.4 Patients with premature ventricular complexes (PVCs) and ventricular tachycardia are also at increased risk. While there is no standard list of SCA symptoms and SCA typically occurs without warning, SCA risk factors include: Survival of a previous SCA episode Previous MI Ejection Fraction (EF) indicator of 40 or less History of heart disease or heart rhythm disorders Family history of SCA or other heart disease

Magnitude of the problem

• SCA and subsequent death (sudden cardiac death, SCD) is a major health problem, claiming as many as 450,000 lives every year in the U.S.⁵
• SCA is the leading single cause of death in the U.S. and second leading cause of death in the U.S. after all cancers combined.⁶
• SCA accounts for approximately 19% of all deaths in the U.S.⁷
• Most SCA victims are on average 60 years of age, and many victims are relatively healthy and lead active lives right up to the moment when SCA strikes.⁸
• People who have had a previous myocardial infarction have a 4-6 times higher risk of SCA than the general population. In people diagnosed with chronic heart failure (CHF), SCA occurs at 6-9 times the rate of the general population.⁵
• SCA is responsible for approximately 60% of deaths in New York Heart Association (NYHA) Class II or III CHF patients.⁹
• Only 5-6% of patients survive a SCA event.³

Treatment Options for Sudden Cardiac Arrest
A life threatening arrhythmia or SCA typically can be reversed, but only if treated within minutes with an electrical shock via an automated external defibrillator (AED)or with an implantable cardioverter defibrillator (ICD). The American Heart Association recommends defibrillation within 3-5 minutes of arrest, or sooner, for cardiac arrests occurring outside the hospital.¹⁰ In the U.S., on average, it takes emergency medical services teams 6-12 minutes to arrive.¹¹ SCA survival rates drop 7–10 percent for every minute without defibrillation.¹²

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³Pell, JP. Presentation, management and outcome of out-of-hospital cardiopulmonary arrest: comparison by underlying etiology. Heart. 2003;89:839-842.

⁴Moss AJ, Zareba W, Hall WJ, et al., for the Multicenter Automatic Defibrillator Implantation Trial II Investigators, Prophylactic Implantation of a Defibrillator in Patients with Myocardial Infarction and Reduced Ejection Fraction. N Engl J Med. 2002;346:877-83.

⁵Zheng Z, Croft J, Giles W, Mensah G. Sudden cardiac death in the United States, 1989-1998. Circulation. 2001;104:2158-2163.

⁶American Cancer Society, Inc., Surveillance Research, Cancer Facts and Figures 2001.

⁷National Vital Statistics Report, 2001; 49(11).

⁸American Heart Association. Heart Disease and Stroke Statistics, 2004 Update. Dallas, Tex.: American Heart Association; 2003.

⁹MERIT-HF study group. Effect of Metoprolol CR/XL in chronic heart failure: Metoprolol CR/XL Randomized Intervention Trial in Congestive Heart Failure (MERIT-HF). Lancet. 1999;353.

¹⁰American Heart Association, Inc., Guidelines 2000 for cardiovascular resuscitation and emergency cardiovascular care. Circulation. 2000;102(8):11-384.

¹¹Medtronic review of published clinical literature.