Sudden Cardiac Arrest

What is Sudden Cardiac Arrest?

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 SCD¹. 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.² 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
• Poor heart pumping (ejection fraction) 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 over 450,000 lives every year in the U.S.³
• 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.⁴
• 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.⁴
• SCA is responsible for approximately 60% of deaths in New York Heart Association (NYHA) Class II or III CHF patients.⁵
• Only 5-6% of patients survive a SCA event.¹

Treatment Options

SCA 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.⁶ In the U.S., on average, it takes emergency medical services teams 6-12 minutes to arrive.⁷ SCA survival rates drop 7-10 percent for every minute without defibrillation.⁸

The Cost of ICD Therapy

Research shows that ICDs provide an invaluable form of life insurance for people most at risk. Evidence-based medicine has demonstrated that ICDs significantly reduce death among Americans at highest risk:

• 31% reduction in death among SCA survivors from a second event.⁹
• 31% reduction in death among post-heart attack sufferers.¹⁰

Despite these statistics, ICDs are underutilized.

• Fewer than 20% of currently indicated patients receive the benefits of an ICD despite being at high risk for sudden death.¹¹

The value of ICDs outweighs their cost to the system.

• The cost per day of ICD protection has decreased by nearly 90% over the last 10 years from more than $90 in 1990 to approximately $13 today (equivalent to the cost of optimal medical therapy for these same patients).¹¹
• ICD Medicare expenditures are significantly less than for other cardiovascular procedures. In 2002, Medicare reimbursed $1.2 billion for ICD procedures vs. $6.4 billion for stent implants and $7.8 billion for bypass surgery.¹²
• The cost of ICD therapy per year is less than 0.2% of projected Medicare spending over the next 10 years.¹³

Reference
¹Pell JP. Presentation, management and outcome of out-of-hospital cardiopulmonary arrest: comparison by underlying etiology. Heart. 2003;89:839-842.
² Moss 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 Infraction and Reduced Ejection Fraction. N Engl J Med. 2002;346:877-83.
³Zheng Z, Croft J, Giles W, Mensah G. Sudden cardiac death in the United States, 1989-1998. Circulation. 2001;104:2158-2163.
⁴ American Heart Association. Heart Disease and Stroke Statistics, 2004 Update. Dallas, Tex.: American Heart Association; 2003.
⁵MERIT-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.
⁶ American Heart Association, Inc., Guidelines 2000 for cardiovascular resuscitation and emergency cardiovascular care. Circulation. 2000;102(8):11-384.
⁷ Medtronic review of published clinical literature.
⁸Cummins RO. From concept to standard-of-care? Review of the clinical experience with automated external defibrillators. Annals of Emergency Medicine 1989,18: 1269-75.
⁹The AVID Investigators. Antiarrhythmics Versus Implantable Defibrillators (AVID)-Rationale, Design, and Methods. Am J Cardiol. 1995;75:470-475.
¹⁰Moss 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 Infraction and Reduced Ejection Fraction. N Engl J Med. 2002;346:877-83.
¹¹ Steinhaus D, Cardinal D, Connelly DT, et al. Cost savings with nonthoracotomy implantable cardioverter defibrillators, Am J Cardiol. 1996; 78:1255-1259.
¹² Calculated from Healthcare Financing Review, Medicare and Medicaid Statistical Supplement, 2001 (Expenditures updated to 2002 $US with the medical component of the CPI).
¹³IMS America 2001 Pharmaceutical sales figures as viewed at:www.cms.hhs.govt/statistics/nhe/historical/t2asp.