This document addresses the use of an implantable cardioverter-defibrillator to monitor heart rhythm and deliver an electrical shock when a life threatening ventricular arrhythmia is detected.

For information regarding other technologies for cardiac disease, see:

• MED.00055 Wearable Cardioverter Defibrillators;
• SURG.00064 Cardiac Resynchronization Therapy (CRT) with or without an Implantable Cardioverter Defibrillator (CRT/ICD) for the Treatment of Heart Failure

Medically Necessary:

ADULT Indications:

Implantable cardioverter-defibrillator (ICD) therapy in adults is considered medically necessary for the treatment of ventricular tachyarrhythmias and for the prevention of sudden cardiac death (SCD) in individuals who are receiving optimal medical therapy and have a reasonable expectation of survival with a good functional status for more than 1 year when one of the following indications is present:

1. After evaluation to define the cause of the event and to exclude any completely reversible causes in survivors of cardiac arrest due to ventricular fibrillation (VF) or hemodynamically unstable sustained ventricular tachycardia (VT); or
2. Those with structural heart disease and spontaneous sustained VT, whether hemodynamically stable or unstable; or
3. Those with syncope of undetermined origin with clinically relevant, hemodynamically significant sustained VT or VF induced at electrophysiological study; or
4. Those with left ventricular ejection fraction (LVEF) less than 35% due to prior myocardial infarction (MI) who are at least 40 days post-MI and are in New York Heart Association (NYHA) functional Class II or III; or
5. Those with nonischemic dilated cardiomyopathy (NIDCM) who have an LVEF less than or equal to 35% and who are in NYHA functional Class II or III; or
6. Those with ischemic cardiomyopathy* and who have had no MI in the past 40 days and have an LVEF less than 30% and are in NYHA functional Class I;  or
7. Those with nonsustained VT due to prior MI, LVEF less than 40%, and inducible VF or sustained VT at electrophysiological study; or
8. Those with long-QT syndrome who are experiencing syncope or VT while receiving beta blockers. 

*Ischemic cardiomyopathy: left ventricular systolic dysfunction associated with marked stenosis (at least 75% narrowing) of at least 1 of the 3 major coronary arteries, or a documented history of myocardial infarction.

Note: For use of combined ICD/Biventricular pacing (CRT-ICD) devices, in cases of NYHA Class IV heart failure and for other indications, see SURG.00064 Cardiac Resynchronization Therapy (CRT), with or without an Implantable Cardioverter Defibrillator (CRT/ICD) for the Treatment of Heart Failure.

PEDIATRIC Indications:

Implantable cardioverter-defibrillator (ICD) therapy in children is considered medically necessary for the treatment of ventricular tachyarrhythmias and for the prevention of sudden cardiac death (SCD) in individuals who are receiving optimal medical therapy and have a reasonable expectation of survival with a good functional status for more than 1 year when one of the following indications is present:

1. For survivors of cardiac arrest after evaluation to define the cause of the event and to exclude any reversible causes; or
2. For individuals with symptomatic sustained VT in association with congenital heart disease who have undergone hemodynamic and electrophysiological evaluation; (Catheter ablation or surgical repair may offer possible alternatives in carefully selected individuals) or
3. For individuals with congenital heart disease with recurrent syncope of undetermined origin in the presence of either ventricular dysfunction or inducible ventricular arrhythmias at electrophysiological study.

Investigational and Not Medically Necessary:

The use of an implantable cardioverter-defibrillator is considered investigational and not medically necessary for any other diagnosis not listed above as medically necessary under Adult Indications or Pediatric Indications.

ICDs are an important treatment option for patients with a history of life-threatening ventricular arrhythmias. Randomized clinical trials have shown that ICD use significantly reduces mortality rates for those patients with coronary artery disease (CAD) and/or a prior MI who have poor ventricular function. Although ICDs for the treatment of atrial fibrillation have been used in studies, evidence on efficacy and long-term outcomes is limited, and thus, clear conclusions concerning the efficacy of this treatment modality cannot be drawn.

Available literature indicates that ICDs are now widely used for the secondary prevention of SCD, due to VF or VT. ICD implantation is the generally accepted treatment for patients who have experienced an episode of VF not accompanied by an acute MI or other transient or reversible cause. Accepted guidelines prefer this treatment in patients with sustained VT, causing syncope or hemodynamic compromise. As primary prevention, the literature shows that ICD use is superior to conventional antiarrhythmic drug therapy in patients who have survived an MI and who have spontaneous, non-sustained VT, a low ejection fraction, and inducible VT at electrophysiological study.

Two prospective, randomized, controlled trials compared the use of ICDs to that of conventional therapy: the Multi-Center Automatic Defibrillator Implantation Trial (MADIT; n=196) and the Multi-Center Automatic Defibrillator Implantation Trial II (MADIT II; n=1,232). Both trials were conducted on patients with CAD who had experienced MIs and who had reduced LVEFs. Both trials were well designed and of good quality. The observed all-cause mortality rate in the conventionally treated group was somewhat lower in MADIT II (19.8%, with average follow-up at 20 months) than in MADIT (38.6%, with average follow-up at 27 months), suggesting some differences in the baseline mortality risk between these two populations. Both trials reported that ICD treatment resulted in more statistically significant reductions in all-cause mortality (primary endpoint) than conventional therapy did. The MADIT and MADIT II trials provide consistent evidence that patients with CAD, prior MI and reduced LVEF who meet selection criteria for either trial have significantly reduced mortality when treated with ICDs than when given conventional therapy (Moss, 1996).

The Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial was a prospective, randomized study to test the hypothesis that an ICD will reduce the risk of sudden death in patients with non-ischemic cardiomyopathy and moderate-to-severe left ventricular dysfunction. Inclusion criteria were: LVEF < 36%, the presence of ambient arrhythmias, a history of symptomatic heart failure, and the presence of non-ischemic dilated cardiomyopathy (NIDCM). The primary endpoint was death from any cause; the secondary endpoint was sudden death from arrhythmia. A total of 458 patients were enrolled: 229 were randomly assigned to receive standard medical therapy and 229 to receive standard medical therapy plus a single-chamber ICD. Results of the study included 68 deaths, 28 of which occurred in the ICD group, as compared to 40 in the standard therapy group (hazard ratio - 0.65; 95%; confidence interval - 0.40-1.06; p=0.08). The mortality rate at two years was 14.1% in the standard therapy group (annual mortality rate, 7%) and 7.9% in the ICD group. There were 17 sudden deaths from arrhythmia: three in the ICD group and 14 in the standard therapy group (hazard ratio - 0.20; 95% confidence interval - 0.06 to 0.71; P=0.006). The researchers noted that fewer patients died in the ICD group than in the standard therapy group (28 vs. 40), but that the difference in survival was not significant (p=0.08). The researchers concluded that this was still a well-supported study, based on the p value results (Schaechter, 2003).

A post-hoc analysis of the DEFINITE trial data was conducted by Kadish and colleagues (2006) which noted that study subjects with reversible causes of left ventricular dysfunction had been excluded from the DEFINITE trial. The authors noted that the time immediately after development of cardiomyopathy may be a time when the disease process and consequent remodeling are in rapid evolution which may stabilize with time. This information would appear to support the medical necessity criterion regarding the duration of NIDCM, (i.e., of greater than nine months), in order to meet medical necessity (Kadish, 2006).

The Defibrillator in Acute Myocardial Infarction Trial (DINAMIT) randomized 674 adult patients to receive either an ICD or no ICD within 40 days of an MI (Hohnloser, et al. on behalf of the DINAMIT Investigators, 2004). All patients had reduced ejection fractions (ejection fraction ≤ 35%) and impaired cardiac autonomic function. The primary outcome was mortality from any cause, and the secondary outcome was death from arrhythmia. During a mean follow-up of 30 ± 13 months, there was no difference in overall mortality between the two groups. Of 120 patients who died, 62 were in the ICD group, and 58 were in the control group. There were 12 deaths due to arrhythmia in the ICD group and 29 in the control group. There were 50 deaths from nonarrhythmic causes in the ICD group, however, and 29 in the control group. The authors concluded that ICD therapy does not reduce overall mortality in high-risk patients who have recently had an MI. Although ICD therapy was associated with a reduction in arrhythmia-related death, this was offset by an increase in nonarrhythmic-related death.

The Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) was conducted to test whether amiodarone therapy or an ICD will improve survival, compared to a placebo in adult patients with systolic dysfunction from ischemic dilated cardiomyopathy (IDCM) or non-ischemic dilated cardiomyopathy (NIDCM) who also have NYHA class II or class III heart failure, chronic stable congestive heart failure (CHF) and reduced LVEF less than or equal to 35%. A total of 2,521 patients were randomly assigned: 847 received placebo plus conventional heart failure therapy; 845 received amiodarone plus conventional heart failure therapy; and 829 received single-lead ICD plus conventional heart failure therapy. The results of the trial showed a significant reduction in mortality in the ICD group, compared to the placebo group: (hazard ratio compared to control = 0.77; 97.5% CI = 0.62-0.96; p=0.007).

For patients with IDCM (see Definitions section on pg. 6), there was a reduction in the mortality hazard ratio for ICD therapy, compared to the control (hazard ratio=0.79; 97.5% CI=0.60-1.04). For patients with NIDCM (see Definitions section on pg. 6), there was a reduction in the mortality hazard ratio for ICD therapy, compared to the control (hazard ratio=0.73; 97.5% CI= 0.50-1.07). Amiodarone therapy did not improve survival. The results of this study showed that overall mortality was lower for patients with NIDCM than for patients with IDCM. The authors concluded that ICD placement is safe and effective for the treatment of ischemic and non-ischemic cardiomyopathy (Bardy, 2005).

In 2009, another study of ICD use as primary prevention of SCD early after acute MI was published. This study was a randomized, prospective, open-label, investigator-initiated, multicenter trial that registered 62,944 unselected patients with MI. Of this total, 898 patients were enrolled 5 to 31 days after the event if they met certain clinical criteria (a LVEF ≤40% with a heart rate of 90 or more beats per minute on the first available electrocardiogram or non-sustained VT ≥150 beats per minute during Holter monitoring or both criteria). Of the 898 patients enrolled, 445 were randomly assigned to treatment with an ICD and 453 were treated with medical therapy alone. During a mean follow-up of 37 months, 233 patients died: 116 patients in the ICD group and 117 patients in the control group. Overall mortality was not reduced in the ICD group (hazard ratio, 1.04; 95% confidence interval [CI], 0.81 to 1.35; P = 0.78). There were fewer incidence of SCD in the ICD group than in the control group (27 vs. 60; hazard ratio, 0.55; 95% CI, 0.31 to 1.00; P = 0.049), but the number of non-sudden cardiac deaths was higher (68 vs. 39; hazard ratio, 1.92; 95% CI, 1.29 to 2.84; P = 0.001). Hazard ratios were similar among the three groups of patients categorized according to the enrollment criteria they met. Prophylactic ICD therapy did not reduce overall mortality among patients with acute MI and clinical features that placed them at increased risk (Steinbeck, 2009).

In 2006, the American College of Cardiology (ACC), in conjunction with the American Heart Association (AHA), the European Society of Cardiology (ESC), the European Heart Rhythm Association (EHRA), and the Heart Rhythm Society (HRS) published practice guidelines for the management of patients with ventricular arrhythmias and the prevention of SCD. The guidelines, which were based on published evidence, expert opinion, and medical consensus, provide recommendations for use of ICDs, in addition to other recommendations related to diagnostics and medical/surgical treatment options for a variety of cardiac conditions. In 2008, the ACC/AHA/HRS published updated guideline recommendations for Device-Based Therapy of Cardiac Rhythm Abnormalities (Epstein, 2008). These guidelines update the prior 2002 ACC/AHA/NASPE Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices (Gregoratos, et al., 2002). The ACC/AHA/HRS guidelines have been updated due to the expanding body of knowledge and experience related to the treatment of bradyarrhythmias and tachyarrhythmias, as well as the significant advances in the technology of device-based therapy for these conditions. These guidelines are intended to add to the information in the former 2002 ACC/AHA/NASPE guidelines, as well as the 2006 ACC/AHA/ESC Guidelines for Management of Patients with Ventricular Arrhythmias and the Prevention of SCD (Zipes, et al., 2006). This updated 2008 guidance document reviews available clinical trial data in detail and also provides specific guideline recommendations for use of ICD devices in adults and also in the pediatric population, which have been incorporated into the medical necessity criteria in this document.

According to this ACC/AHA/HRS guideline document (Epstein, 2008):

The indications for ICD implantation in young patients and those with congenital heart disease have evolved over the past 15 years based on data derived primarily from adult randomized clinical trials. Similar to adults, ICD indications have evolved from the secondary prevention of SCD to the treatment of patients with sustained ventricular arrhythmias to the current use of ICDs for primary prevention in patients with an increased risk of SCD. However, in contrast to adults, there are minimal prospective data regarding ICD survival benefit, because fewer than 1% of all ICDs are implanted in pediatric or congenital heart disease patients. Considerations, such as the cumulative lifetime risk of SCD in high-risk patients and the need for decades of antiarrhythmic therapy make the ICD an important treatment option for young patients. Prospective identification and treatment of young patients at risk for sudden death is crucial because compared with adults, a very low percentage of children undergoing resuscitation survive to hospital discharge…Because of concern about drug-induced proarrhythmia and myocardial depression, an ICD (with or without cardiac resynchronization therapy [CRT]) may be preferable to antiarrhythmic drugs in young patients with dilated cardiomyopathy (DCM) or other causes of impaired ventricular function who experience syncope or sustained ventricular arrhythmias…The role of ICDs in primary prevention for children with genetic channelopathies, cardiomyopathies, and congenital heart defects should be defined more precisely and is an area in need of further research (Epstein, 2008).

In 2009, the ACC/AHA published a focused update to the 2005 Guidelines for the Diagnosis and Management of Heart Failure in Adults which gave a Class IIa recommendation for ICD placement in IDCM patients who are at least 40 days post-MI, have an LVEF of 30% or less, are NYHA functional class I on chronic optimal medical therapy, and have reasonable expectation of survival with a good functional status for more than 1 year (Hunt, 2009). This was based, in part, on the findings of the SCD-HeFT trial previously described (Bardy, 2005) and has been incorporated into the medical necessity criteria for adult indications.

The Centers for Medicare and Medicaid Services (CMS) expanded its national coverage determination policy (January 27, 2005), to include patients with IDCM and NIDCM, subject to additional policy limitations and requirements regarding data collection. This expanded policy is based on the results of recently published trial data, as described above.

Description of Relevant Disease
SCD (also called sudden arrest) is defined as unexpected death, resulting from an abrupt loss of heart function (cardiac arrest). All known heart diseases can lead to cardiac arrest and SCD. Most of the cardiac arrests that lead to SCD occur when the electrical impulses in the diseased heart become rapid (VT) or chaotic (VF) or both. This irregular rhythm causes the heart to suddenly stop beating. Some cardiac arrests are due to extreme slowing of the heart (bradycardia). Brain death and permanent death start to occur in just four to six minutes after someone experiences cardiac arrest. Cardiac arrest is reversible in most victims if it is treated within a few minutes with an electrical shock to the heart to restore a normal heartbeat (defibrillation). Cardiovascular mortality as a consequence of VF or VT continues to be a major health problem, despite advances in the overall management of cardiovascular disease. SCD kills approximately 400,000 people per year, with survival rates for cardiac arrest less than 5% in most industrialized countries. If the cardiac arrest was due to VT or VF, survivors are at risk for another arrest, especially if they have underlying heart disease.

Description of Implantable Defibrillators (ICD)
Defibrillation is a process in which an electronic device gives an electric shock to the heart. This helps re-establish normal contraction rhythms in a heart having dangerous arrhythmia or in cardiac arrest. A surgically implanted ICD is a device used in patients at high risk for SCD due to arrhythmia, usually due to sustained ventricular tachyarrhythmia. The device is connected to leads positioned inside the heart or on its surface. These leads are used to deliver electrical shocks, sense the cardiac rhythm and sometimes pace the heart, as needed. The various leads are connected to a pulse generator, which is implanted in a pouch beneath the skin of the chest or abdomen. The ICD is designed to continuously monitor an individual's heart rate, recognize VF or VT, and deliver an electric shock to terminate these arrhythmias, in order to reduce the risk of sudden death. Multiple ICD devices have been approved by the U.S. Food and Drug Administration (FDA) through the premarket approval (PMA) process, subject to FDA-approved labeling indications.

Arrhythmia (or dysrhythmia): problems that affect the electrical system of the heart muscle, producing abnormal heart rhythms; may be classified as either atrial or ventricular, depending on which part of the heart they originate from

Atrial Fibrillation: a condition in which the atrium (the heart's two upper chambers) produce uncoordinated electrical signals

Cardiomyopathy: a disease in which the heart muscle becomes inflamed and doesn't work as well as it should; there are three main types of cardiomyopathy:

• Dilated - this is the most common form, in which the heart cavity is enlarged and stretched (cardiac dilation); the heart is weak and doesn't pump normally, and most patients develop congestive heart failure; abnormal heart rhythms and disturbances in the heart's electrical conduction also may occur
  
• Hypertrophic - in this condition, the muscle mass of the left ventricle enlarges or "hypertrophies;" in one form of the disease, the wall between the two pumping chambers becomes enlarged and obstructs the blood flow from the left ventricle; in the other form of the disease, non-obstructive hypertrophic cardiomyopathy, the enlarged muscle doesn't obstruct blood flow;
  
• Restrictive - this is the least common type in the United States; the myocardium (heart muscle) of the ventricles becomes excessively "rigid," making it more difficult for the ventricles to fill with blood between heartbeats; this type of cardiomyopathy is usually due to another disease process

Ischemic Cardiomyopathy (IDCM): left ventricular systolic dysfunction (or disease of the heart muscle) associated with at least 75 percent narrowing of at least one of the three major coronary arteries (marked stenosis) or a documented history of myocardial infarction

Nonischemic Cardiomyopathy (NIDCM): refers to left ventricular systolic dysfunction (or disease of the heart muscle) that is not associated with Coronary Artery Disease (CAD) or narrowing of the coronary arteries; there are a few different types of nonischemic cardiomyopathy but all involve thickening (abnormal enlargement) of the walls of the heart and progressive weakening of the pumping efficiency of the heart

Congestive heart failure (CHF): or heart failure: a condition in which the heart can't pump enough blood to the body's other organs; the "failing" heart keeps working but not as efficiently as it should; as blood flow out of the heart slows, blood returning to the heart through the veins backs up, causing congestion in the tissues

Coronary Artery Disease (CAD): refers to heart problems caused by narrowed heart arteries; when arteries are narrowed, less blood and oxygen reaches the heart; this can ultimately lead to a heart attack (myocardial infarction)

Defibrillation: a process in which an electronic device (a defibrillator) gives the heart an electric shock, helping to re-establish normal contraction rhythms in a heart that is not properly beating; this may be done using an external device or by a device implanted in the body

Ejection Fraction (EF): the percentage of blood ejected from the left ventricle with each heartbeat; normal readings would be in the 58-70% range and lower values would indicate ventricular dysfunction

Electrophysiology Studies: performed in the cardiac catheterization laboratory; such studies evaluate electro- physiological properties of the heart, such as automaticity, conduction, and whether the condition is refractory to management with medications; additional capabilities of this testing include: ability to initiate and terminate tachycardia; to map activation sequences; and to evaluate patients for various forms of therapy and judge response to therapy

Myocardial Infarction (MI): the medical term for heart attack; a heart attack occurs when the blood supply to part of the heart muscle (the myocardium) is severely reduced or blocked (stenosed)

New York Heart Association (NYHA) Definitions:
the NYHA classification of heart failure is a 4-tier system that categorizes patients based on subjective impression of the degree of functional compromise; the four NYHA functional classes are as follows:

• Class I - patients with cardiac disease but without resulting limitation of physical activity; ordinary physical activity does not cause undue fatigue, palpitation, dyspnea, or anginal pain; symptoms only occur on severe exertion
  
• Class II - patients with cardiac disease resulting in slight limitation of physical activity; they are comfortable at rest; ordinary physical activity, (e.g., moderate physical exertion, such as carrying shopping bags up several flights of stairs) results in fatigue, palpitation, dyspnea, or anginal pain
• Class III - patients with cardiac disease resulting in marked limitation of physical activity; they are comfortable at rest; less than ordinary activity causes fatigue, palpitation, dyspnea or anginal pain
• Class IV - patients with cardiac disease resulting in inability to carry on any physical activity without discomfort; symptoms of heart failure or the anginal syndrome may be present even at rest; if any physical activity is undertaken, discomfort is increased

QRS Complex: refers to a portion of an electrocardiogram (EKG) reading, which represents the spread of the electrical impulse through the ventricles

Sudden Cardiac Death: (also called sudden death) is death resulting from an abrupt loss of heart function (cardiac arrest)

Ventricular tachyarrhythmias: a medical term for a rapid heartbeat that may be regular or irregular and arises from the ventricle or pumping chamber of the heart; two common tachyarrhythmias are ventricular tachycardia and ventricular fibrillation

Ventricular Fibrillation: (Vfib or VF) a condition in which the heart's electrical activity becomes disordered; when this happens, the heart's lower (pumping) chambers contract in a rapid, unsynchronized fashion, (i.e., the ventricles "flutter" rather than beat), and the heart pumps little or no blood

Ventricular Tachycardia: (Vtach or VT) is a fast regular heart rate (usually of 100 or more beats per minute) that starts in the lower chambers (ventricles); VT may result from serious heart disease and usually requires prompt treatment

Sustained/Non-sustained Ventricular Tachycardia: if the fast rhythm self-terminates within 30 seconds, it is considered a non-sustained ventricular tachycardia; if the rhythm lasts more than 30 seconds, it is known as a sustained ventricular tachycardia (even if it terminates on its own after 30 seconds)

The following codes for treatments and procedures applicable to this document are included below for informational purposes.  Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage or these services at it applies to an individual member.

When services may be Medically Necessary when criteria are met:

When services are Investigational and Not Medically Necessary:
For the procedure codes listed above specified as ICD, when criteria are not met, or when the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary.

Peer Reviewed Publications:

1. Bardy GH, Lee KL, Mark DB, et al. Amiodarone or an implantable cardioverter–defibrillator for congestive heart failure (SCD-HeFT Trial). N Engl J Med. 2005; 352(3):225-237.
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3. Bristow MR, Saxon LA, Boehmer J, et al. Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure. N Engl J Med. 2004; 350:2140-2150.
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6. Buxton AE, Sweeney MO, Wathen MS, et al. QRS duration does not predict occurrence of ventricular tachyarrhythmias in patients with implanted cardioverter-defibrillators. J Am Coll Cardiol. 2005; 46(2):310-316.
7. Buxton AE, Lee KL, Fisher JD, et al.. A randomized study of the prevention of sudden death in patients with coronary artery disease. N Engl J Med. 1999; 341:1882-1890.
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18. Engelstein ED. Prevention and management of chronic heart failure with electrical therapy. Am J Cardiol. 2003; 91(9):62. 
19. Exner DV, Klen GJ, Prytowsky EN. Primary prevention of sudden cardiac death with implantable defibrillator therapy in patients with cardiac disease: can we afford to do it? (Can We Afford Not To?). Circ. 2001; 104(13):1564-1570.
20. Ezekowitz JA, Armstrong PW, McAlister FA. Implantable cardioverter-defibrillators in primary and secondary prevention: A systemic review of randomized, controlled trials. Ann Intern Med. 2003; 138(6):445-452.
21. Ezekowitz JA, Rowe BH, Dryden DM, et al.  Systematic review:  cardioverter defibrillators for adults with left ventricular systolic dysfunction.  Ann Intern Med. 2007; 147:251-262.
22. Fisher JD, Buxton AE, Lee KL, et al. Designation and distribution of events in the Multicenter UnSustained Tachycardia Trial (MUSTT). Am J Cardiol. 2007; 100(1):76-83. 
23. Goldenberg I, Moss AJ, Hall, J, et al. Causes and consequences of heart failure after prophylactic implantation of a defibrillator in the multicenter automatic defibrillator implantation trial II. Circulation. 2006; 113(24):2810-2817. 
24. Goldenberg I, Vyas AK, Hall WJ, et al. Risk stratification for primary implantation of a cardioverter-defibrillator in patients with ischemic left ventricular dysfunction. J Am Coll Cardiol. 2008; 51(3):288-296.
25. Greenberg H, Case RB, Moss AJ, et al. and MADIT-II Investigators. Analysis of mortality events in the Multicenter Automatic Defibrillator Implantation Trial (MADIT-II). J Am Coll Cardiol. 2004; 43(8):1459-1465.
26. Heidenreich PA, Keefe B, McDonald KM, et al. Overview of randomized trials of antiarrhythmic drugs and devices for the prevention of sudden cardiac death. Am Heart J. 2002; 144(3):422-430.
27. Hlatky MA. Evidence-based use of cardiac procedures and devices. N Engl J Med. 2004; 350:2126-2128.
28. Hodgkinson KA, Parfrey PS, Bassett AS, et al. The impact of implantable cardioverter-defibrillator therapy on survival in autosomal-dominant arrhythmogenic right ventricular cardiomyopathy (ARVD5). J Am Col Cardiol. 2005; 45(3):400-408. 
29. Hohnloser SH, Kuck KH, Dorian P, et al. Prophylactic use of an implantable cardioverter-defibrillator after acute myocardial infarction. N Engl J Med. 2004; 351:2481-2488. 
30. Huang DT, Sesselberg HW, McNitt S, et al. Improved survival associated with prophylactic implantable defibrillators in elderly patients with prior myocardial infarction and depressed ventricular function: a MADIT-II substudy. J Cardiovasc Electrophysiol. 2007; 18(8):833-838. 
31. Kadish A, Dyer A, Daubert JP, et al. Prophylactic defibrillator implantation in patients with nonischemic dilated cardiomyopathy.N Engl J Med. 2004; 350:2151-2158.
32. Kadish A, Schaechter A, Subacius H, et al.  Patients with recently diagnosed nonischemic cardiomyopathy benefit from implantable cardioverter-defibrillators.  J Am Coll Cardiol. 2006; 47:2477-2482.
33. Khairy P, Harris L, Landzberg MJ, et al. Implantable cardioverter-defibrillators in tetralogy of Fallot. Circulation. 2008; 117(3):363-370. Epub 2008 Jan 2. 
34. Kupersmith J. The past, present, and future of the implantable cardioverter-defibrillator. Am J Med. 2002;  113(1); 82-84.
35.  Kusumoto, FM, Goldschlager N. Device therapy for cardiac arrhythmias. JAMA. 2002; 287(14):1848-1852.
36. Marchlinski FE, Jessup M.  Timing the implantation of implantable cardioverter-defibrillators in patients with nonischemic cardiomyopathy.  J Am Coll Cardiol. 2006; 47:2483-2485.
37. Mark DB, Anstrom KJ, Sun JL, for the Sudden Cardiac Death in Heart Failure Trial Investigators, et al. Quality of life with defibrillator therapy or amiodarone in heart failure. N Engl J Med. 2008; 359:999-1008.
38. Maron BJ, Spirito P, Shen WK, et al. Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy. JAMA. 2007; 298(4):405-412.
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41. Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med. 2002; 346:877-883.
42. Nagahara D, Nakata T, Hashimoto A, et al. Predicting the need for an implantable cardioverter defibrillator using cardiac metaiodobenzylguanidine activity together with plasma natriuretic peptide concentration or left ventricular function. J Nucl Med. 2008; 49(2):225-233. Epub 2008 Jan 16.
43. Nanthakumar K, et al. Is inappropriate implantable defibrillator shock therapy predictable? Journal of Interventional Cardiac Electrophysiology. 8, 215-220.
44. Parkes JB, Milne AR. Implantable cardioverter-defibrillators in arrhythmias: a rapid and systematic review of effectiveness. Heart. 2002; 87(5):438-442.
45. Passman R, Subacius H, Ruo B, et al.  Implantable cardioverter defibrillators and quality of life: results from the defibrillators in nonischemic cardiomyopathy treatment evaluation study (DEFINITE). Arch Intern Med. 2007; 167(20):2226-2232.
46. Poole JE, Johnson GW, Hellkamp AS, et al. Prognostic importance of defibrillator shocks in patients with heart failure. N Engl J Med. 2008; 359:1009-1017.
47. Raviele A, Bongiorni MG, Brignole M, et al. Early EPS/ICD strategy in survivors of acute myocardial infarction with severe left ventricular dysfunction on optimal beta-blocker treatment.  The Beta-blocker Strategy plus ICD trial.  Europace. 2005; 7(4):327-337.
48. Reddy VY, Reynolds MR, Neuzil P, et al. Prophylactic catheter ablation for the prevention of defibrillator therapy. N Engl J Med. 2007; 357(26):2657-2665. Comment in: N Engl J Med. 2007; 357(26):2717-2719.
49. Schaechter A, Kadish AH, et al. Defibrillators in non-ischemic cardiomyopathy treatment evaluation (DEFINITE).  Card Electrophysiol Rev. 2003; 7(4):457-462.
50. Scheinman MM, Keung E.  The year in clinical cardiac electrophysiology.  J Am Coll Cardiol. 2007; 49:2061-2069.
51. Schlapfer J, Rapp F, Kappenberger L, et al. Electrophysiologically guided amiodarone therapy versus the implantable cardioverter-defibrillator for sustained ventricular tachyarrhythmias after myocardial infarction: Results of long-term follow-up. J Am Coll Cardiol. 2002; 39(11):1813-1819.
52. Steinbeck G, Andresen D, Seidl K, et al. Defibrillator implantation early after myocardial infarction.  N Engl J  Med. 2009; 361:1427-1436.
53. Steinberg JS, Martins J, et al. Antiarrhythmic drug use in the implantable defibrillator arm of the antiarrhythmics versus implantable defibrillator (AVID) study. Am Heart J. 2001; 142(3):520-529.
54. Swygman C, Wang PJ, Link MS, et al. Advances in implantable cardioverter-defibrillators. Curr Op Card. 2002; 17(1):24-28.
55. Varma N. Rationale and design of a prospective study of the efficacy of a remote monitoring system used in implantable cardioverter defibrillator follow-up: the Lumos-T reduces routine office device follow-up study (TRUST). Am Heart J. 2007; 154(6):1029-1034.
56. Wilber DJ, Zareba W, Hall WJ, et al.  Time dependence of mortality risk and defibrillator benefit after myocardial infarction. Circulation. 2004; 109:1082-1084.
57. Yap SC, Roos-Hesselink JW, Hoendermis ES, et al.  Outcome of implantable cardioverter defibrillators in adults with congenital heart disease: a multi-centre study. Eur Heart J. 2007; 28(15):1854-1861.

Government Agency; Medical Society; and Other Authoritative Publications:

1. American Heart Association (AHA) web site: Sudden cardiac death. 2005b.  Available at: http://www.americanheart.org/presenter.jhtml?identifier=4741.  Accessed on September 21, 2009.
2. Antman EM, Hand M, Armstrong PW, et al. 2007 Focused Update of the ACC/AHA 2004 Guidelines for the Management of Patients With ST-Elevation Myocardial Infarction: American College of Cardiology/American Heart Association Task Force on Practice Guidelines Developed in Collaboration With the Canadian Cardiovascular Society Endorsed by the American Academy of Family Physicians 2007 Writing Group to Review New Evidence and Update the ACC/AHA 2004 Guidelines for the Management of Patients With ST-Elevation Myocardial Infarction, Writing on Behalf of the 2004 Writing Committee. J Am Coll Cardiol. 2008; 51:210-247.  Available at: http://www.acc.org/qualityandscience/clinical/guidelines/stemi/STEMI%20Full%20Text.pdf. Accessed on September 21, 2009.
3. Blue Cross and Blue Shield Association. Use of implantable Cardioverter-Defibrillators for Prevention of Sudden Death in Patients at High Risk for Ventricular Arrhythmia. TEC Assessment, 2004; 19(19).
4. Blue Cross and Blue Shield Association.  Implantable Cardioverter Defibrillators for Primary Prevention of Sudden Death in Patients at High Risk for Ventricular Arrhythmia. TEC Assessment, 2002; 17(10).
5. Bonow RO, Carabello BA, Chatterjee K, et al. 2008 Focused Update Incorporated Into the ACC/AHA 2006 Guidelines for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease) Endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2008; 52:1-142. Available at: http://content.onlinejacc.org/cgi/content/full/52/13/e1.  Accessed on September 21, 2009.
6. Centers for Medicare & Medicaid Services. National Coverage Determination: Implantable Automatic Defibrillators. NCD#20.4.  Effective 01/27/2005.  Available at: http://www.cms.hhs.gov/mcd/viewncd.asp?ncd_id=20.4&ncd_version=3&basket=ncd%3A20%2E4%3A3%3AImplantable+Automatic+Defibrillators.  Accessed on September 21, 2009.
7. Connolly SJ, Hohnloser SJ, and the DINAMIT Steering Committee and Investigators. DINAMIT: Randomized trial of prophylactic implantable defibrillator therapy versus optimal medical treatment early after myocardial infarction: The Defibrillator in Acute Myocardial Infarction Trial. American College of Cardiology Scientific Session 2004. Bethesda, MD: American College of Cardiology; 2004. Available at: http://www.acc04online.org/ondemand/trials1/sessions.asp?link=R.  Accessed on September 22, 2009.
8. Epstein AE, DiMarco JP, Ellenbogen KA, et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices) Developed in Collaboration With the American Association for Thoracic Surgery and Society of Thoracic Surgeons. J Am Coll Cardiol. 2008; 51:1-62.  Available at: http://content.onlinejacc.org/cgi/content/full/51/21/e1#SEC6. Accessed on September 21, 2009.
9. Goldberger JJ, Cain ME, Kadish AH, et al. American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society Scientific Statement on Noninvasive Risk Stratification Techniques for Identifying Patients at Risk for Sudden Cardiac Death. A Scientific Statement from the American Heart Association Council on Clinical Cardiology Committee on Electrocardiography and Arrhythmias and Council on Epidemiology and Prevention. J Am Coll Cardiol. 2008; 52:1179-1199. Available at: http://content.onlinejacc.org/cgi/content/full/52/14/1179.  Accessed on September 22, 2009.
10. Hayes Inc. Hayes Medical Technical Directory.^™  Implanted Cardioverter Defibrillators for Primary Prevention of Sudden Cardiac Death. Lansdale, PA:Hayes, Inc; December 9, 2005.  Search updated February 18, 2009.
11. Hayes Inc.  Hayes Medical Technical Directory.^™  Implanted Cardioverter Defibrillators for Secondary Prevention of Sudden Cardiac Death. Lansdale, PA: Hayes, Inc; November 28, 2005. Search updated February 19, 2009.
12. Hunt SA, Abraham WT, Chin MH, et al. 2009 focused update incorporated into the ACC/AHA 2005 guidelines for the diagnosis and management of heart failure in adults: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2009; 53:e1–90.  Available at: http://content.onlinejacc.org/cgi/reprint/53/15/e1.pdf.  Accessed on October 9, 2009.
13. Jessup M, Abraham WT, Casey DE, et al. writing on behalf of the 2005 Guideline Update for the Diagnosis and Management of Chronic Heart Failure in the Adult Writing Committee. 2009 focused update: ACCF/AHA guidelines for the diagnosis and management of heart failure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2009; 53:1343– 1382.  Available at:  http://content.onlinejacc.org/cgi/reprint/53/15/1343.pdf.  Accessed on September 21, 2009.
14. Maron BJ, McKenna WJ, Danielson GK, et al. ACC/ESC clinical expert consensus document on hypertrophic cardiomyopathy: a report of the American College of Cardiology Task Force on Clinical Expert Consensus Documents and the European Society of Cardiology Committee for Practice Guidelines (Committee to Develop an Expert Consensus Document on Hypertrophic Cardiomyopathy). J Am Coll Cardiol. 2003; 1-27.  Available at: http://www.acc.org/qualityandscience/clinical/consensus/cardiomyopathy/index.pdf.  Accessed on September 22, 2009.
15. McAlister FA, Ezekowitz J, Dryden DM, et al. Cardiac resynchronization therapy and implantable cardiac defibrillators in left ventricular systolic dysfunction. Evid Rep Technol Assess (Full Rep). 2007 Jun;(152):1-199.
16. National Institute for Health and Clinical Excellence (NICE). Implantable cardioverter defibrillators for arrhythmias: Review of Technology Appraisal 11. Technology Appraisal 95. London, UK: NICE; 2006.
17. U.S. Food and Drug Administration (FDA). Center for Devices and Radiological Health.  Implantable Cardioverter Defibrillators.  Available at:http://www.accessdata.fda.gov/scripts/cdrh/devicesatfda/index.cfm.  Accessed on September 22, 2009.
18. Zipes DP, Camm AJ, Borggrefe M, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to develop guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death).  Circ. 2006; 114:1088-1132.  Available at: http://www.acc.org/qualityandscience/clinical/pdfs/VASCD_FullText.8.15.06.pdf.   Accessed on September 22, 2009.

1. U.S. Food and Drug Administration (FDA). Center for Devices and Radiological Health.  FDA Preliminary Public Health Notification: Guidant Ventak Prizm 2 DR and Contak Renewal Implantable Cardioverter Defibrillators. July 14, 2005.  Available at:  http://www.fda.gov/cdrh/safety.html  Accessed on September 22, 2009. 
2. National Institute for Clinical Excellence (NICE) Technology Appraisal Guidance No. 11.  Guidance on the use of implantable cardioverter defibrillators for arrhythmias.  London, UK. NICE; 2000.  Available at:  http://guidance.nice.org.uk/TA95/?c=91497.  Accessed on September 22, 2009.
3. Heart failure. Available at: http://www.heartfailure.org/  Accessed on September 22, 2009.
4. Information about cardiomyopathy.  Cleveland Clinic web site.  Available at:  http://my.clevelandclinic.org/disorders/Cardiomyopathy/hic_What_is_Cardiomyopathy.aspx.  Accessed on September 22, 2009.

Automatic Defibrillator
ICD
Implantable Cardioverter-Defibrillator