Use of Implantable Cardiac Defibrillators Among Older Adults

ABSTRACT: Implantable cardioverter-defibrillators (ICDs) are small, battery-powdered electrical impulse devices that can be implanted in patients at-risk for sudden cardiac death due to ventricular tachycardia and ventricular fibrillation. Determining whether an older adult is an appropriate candidate for ICD placement is complex. This article provides an overview of ICD devices, including indications and complications, with a focus on the unique challenges associated with device usage in older adults.

Implantable cardioverter-defibrillators (ICDs) are small, battery-powered devices used to prevent sudden cardiac death (SCD) in patients at-risk for ventricular tachycardia and ventricular fibrillation. ICDs have the ability to both detect and treat life-threatening arrhythmias by delivering various electrical therapies directly to the heart. In addition, many devices can provide backup pacing for bradycardia.

Initially used in the 1980s, ICDs were originally intended for patients who had survived a cardiac arrest due to ventricular fibrillation or ventricular tachycardia—secondary prevention of SCD.¹ Since then, ICDs have been approved for primary prevention of SCD among patients who are at high risk for such events.² Several large clinical trials provide support for expanded use of ICDs, helping these devices to become more commonplace.^2-4 Among Medicare and Medicaid beneficiaries from 2006 to 2009, there were more than 486,000 ICD placement procedures; 72% of which were for new devices.⁵

Determining whether an older adult is an appropriate candidate for ICD placement is complex. These devices are associated with risks and only prevent a small number of events (ie, most older adults die of nonarrhythmic causes).⁶ Placement of ICDs also raises a number of practical questions, such as the timing of generator replacements, ICD deactivation near the end of life, and post-ICD-firing quality of life (QOL).⁷ Although the decision to place an ICD ultimately may reside with an experienced cardiologist with specialized training in electrophysiology, primary care providers (including geriatricians) should have a good understanding of ICD basics in order to triage referrals appropriately. This article provides an overview of ICD devices, including indications and complications, with a focus on the unique challenges associated with device usage in older adults.
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Indications for ICDs

• Primary prevention. ICD implantation should be considered in patients with nonischemic or ischemic heart disease, left ventricular ejection fraction (LVEF) of 35% or less, and New York Heart Association (NYHA) class II or III symptoms. Additionally, ICDs should be considered for patients with left ventricular (LV) dysfunction due to prior myocardial infarction (MI), who are at least 40 days post-MI, and have an LVEF equal to or less than 30% and are NYHA class I. Table 1⁸ provides a breakdown of the NYHA classification system. 

• Secondary prevention. ICD placement should be considered in patients with current or prior heart failure symptoms and reduced LVEF with a history of cardiac arrest, ventricular fibrillation, or a hemodynamically unstable ventricular arrhythmia. These measures are all based on American College of Cardiology and the American Heart Association (ACC/AHA) Level A guidelines.² In addition, ICDs may also be indicated for patients with other forms of structural heart disease, such as hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and even in those without obvious heart disease (eg, individuals with primary electrical disorders). 

(Outcomes, Placement of ICDs, and Post-ICD Care on Next Page)

Outcomes

Large-scale trials of ICD therapy for both primary and secondary prevention of SCD have shown improved survival when compared to standardized nondevice therapy (Table 2). While there is no absolute age cutoff for device placement, there are several important caveats when considering placement in older adults. ICDs generally confer a mortality benefit 1 year after implantation; therefore, life expectancy of <1 year is considered a contraindication to implantation.⁹ 

Most of the large clinical trials that inform current practice guidelines for ICD placement have an average age of about 65 years; to date, there are no randomized, controlled studies specific to the elderly, particularly those >80 years. Table 3 summarizes several nonrandomized studies that specifically address heart failure in an older population. The results are mixed but at least 1 recent multicenter, prospective study has suggested mortality benefit with ICD placement that persisted even when stratified by age (<65, 65-74, ≥75).¹⁰ 

In the absence of strong clinical data, provider practices regarding implantation are varied,¹¹ but elderly patients are frequently referred for ICD implantation. Recent registry data shows that more than 40% of new ICDs and related devices were placed in patients ≥70 years and more than 10% were placed in patients 80 years or older.⁷

Elderly populations have high rates of heart failure with preserved ejection fraction or diastolic heart failure, which is not an indication for ICD placement. Competing causes of death, such as nonarrhythmic death or pulseless electrical arrhythmia, occur more frequently in the elderly and may limit the benefit of device placement.¹² Current data suggest that while age alone should not be a contraindication for ICD placement, older adults require a more personalized approach with regards to the risks and benefits of device placement.

The cost for ICD placement based upon Medicare weighted average base payments are $32,437 for placement of an ICD, $23,203 for a generator replacement, and $12,790 for replacement of a lead wire.¹³ Cost-effectiveness analysis in the elderly population are also limited by low numbers of subjects enrolled in clinical trials; a recent economic analysis suggested that implanting an ICD in patients ≥75 years of age was associated with a cost of $39,564 to $150,421 per quality-adjusted life year.¹⁴ 

Placement of ICDs 

ICDs are comprised of an electrical generator that is placed subcutaneously or submuscularly and electrodes or leads that are fixed into the cardiac chambers (Figure 1). The procedure, generally performed by an electrophysiologist or less commonly by a cardiologist or cardiac surgeon, is done under conscious sedation. The electrodes are implanted percutaneously using the subclavian/axiallary or cephalic veins. The leads are then fixed onto the ventricular or atrial myocardium under fluoroscopic guidance. 

The “shocking” lead is placed in the right ventricular apex. Some patients may undergo implantation of an atrial lead (placed in the right atrial appendage) for bradycardia or a left ventricular lead (placed in the ventricular branch of the coronary sinus) for heart failure in the setting of systolic dysfunction and a bundle branch block on the electrocardiogram. The lead wires are then attached to the pulse generator that is implanted into a subpectoral pocket, which is subsequently closed using suture material. Immediate risks of device placement include pneumothorax, hematoma formation, vascular damage, or sedation-related complications. Overall, there is a low risk of procedural complications with total deaths within 30 days reported as low as 0.6%.¹⁵ In general, patients are observed overnight and discharged after normal lead position and function are confirmed.

Figure 1. Implantable cardiac device. (Photo courtesy of the National Heart Lung and Blood Institute)

Restrictions 

In general, there are few lifestyle limitations that result from ICD placement. Most recreational activities can be performed, though activities where sudden incapacitation could lead to injury (eg, scuba diving, boating, or skiing) should be restricted or performed with caution.¹⁶ Certain occupations (eg, commercial or professional drivers/pilots) are also restricted while others can be performed under precaution (eg, heavy machinery operators, workers in industrial facilities or power plants).^16,17 

Driving restrictions for noncommercial drivers are recommended immediately after placement (for 1 week) and for 6 months following any ICD firing event, whether appropriate or not.¹⁸ Though previously thought to be a contraindication, safety protocols now allow some patients with ICDs to safely undergo MRI studies under close supervision and monitoring, though in general they should be avoided.¹⁹

Post-ICD Care

Patients generally require follow-up care every 6 months with an electrophysiologist or a cardiologist experienced in device troubleshooting, depending on the type of ICD, battery status, and arrhythmia frequency. Battery longevity is usually 4 to 7 years, depending on the frequency of use after which a patient must undergo a repeat procedure to change the generator unit. Current devices may last up to 10 years. 

Patients with ICDs are able to undergo any surgical procedure including ones that require electrocautery, though devices are usually reprogrammed or disabled during procedures to avoid inappropriate detection/therapies. Advanced cardiovascular life support should not be withheld while awaiting device activation. ICD discharges may be perceptible to those who have skin-to-skin contact with patients, but does not pose a health risk to those performing cardiopulmonary resuscitation.²⁰

Several studies have examined the relationship between age and psychosocial adjustment and QOL after ICD placement. Interestingly, many of these studies suggest that older cohorts of patients have an easier time adjusting to devices as compared with younger adults. Older patients have lower reported rates of anxiety, depression, sleep disturbances, and overall QOL related to device placement.²¹ This may relate to the fact that younger adults are more sensitive to the perceived restrictions on lifestyles that these devices carry.²¹ 

The very elderly (>80-90 years of age) with conventional pacemakers have similar QOL scores compared to their peers, though comparable data is not specifically available for ICDs. In general, QOL scores appear to be inversely related to the number of lifetime discharges a patient receives: Those who received fewer therapies have higher QOL scores as compared to those with more therapies (≥5).²² As with many interventions, it is likely that a patient’s total psychosocial makeup rather than age alone determines his or her QOL after device placement.²³

(Complications and Device Deactivation on Next Page)

Complications 

In experienced hands, the chance of severe perioperative complication should be 1% to 2%.²⁴ The most common early complication involves mechanical failure of the ICD device itself, followed by hematoma formation, myocardial perforation or pericardial effusion, infection, and pneumothorax.¹⁵ Late device failure and resulting explantation occurs at a rate of about 20 extractions per 1000 devices implanted per year.²⁵

Infectious complications of ICD placement include pocket infections, lead-wire infection, bacteremia, endocarditis, and myocardial or perivalvular abscesses. The overall rate of infections in patients undergoing ICD placement is estimated to be 1.9 per 1000 device years.²⁶ The standard of care for serious device infections includes ICD removal in conjunction with extended durations of parenteral antimicrobials (depending on the site of the infection) before eventual device reimplantation. With proper therapy and management, treatment of these serious infections can be very successful.²⁷ A recent prospective study reported that the 2-year mortality for patients with ICD infectious was similar to a control cohort (14% vs. 11%).²⁸ In this study, however, older age was an independent predictor of mortality. 

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Age is another factor to consider in the decision to implant an ICD. Younger patients are more likely to undergo multiple device-related procedures, not only for battery depletion but also lead revision for failure. The latter may be associated with venous stenosis or occlusion, necessitating implantation on the contralateral side or percutaneous intervention of the stenotic segment and reimplantation. Fortunately, an entirely subcutaneous ICD will be clinically available in the near future, obviating the need for vascular invasion with its attendant complications.²⁹ 

Although advancements in ICD programming have reduced the occurrence from previously reported figures, inappropriate shocks can still occur. The incidence of inappropriate therapy ranges from 15% to 35%.³⁰ The most common cause of inappropriate detection or therapies is supraventricular arrhythmias (eg, atrial fibrillation with rapid ventricular rates that exceed the cutoff for detection of ventricular tachycardia or fibrillation).

Device Deactivation and End of Life Issues 

When use of an ICD is no longer compatible with the overall goals of care, these devices should be deactivated.³¹ Deactivation can be performed formally using specialized equipment. In an emergency setting, most cases can be deactivated by placing a doughnut-shaped magnet over the device; the magnet prevents arrhythmia detection and hence device discharge. Such magnets should be made available at any healthcare facility.

The decision to proceed with device deactivation near the end of life can be complicated, particularly in older adults where surrogate decision makers often play a major role. Advanced care planning can improve outcomes and result in fewer inappropriate shocks and shocks near the end of life.^32-34 These types of discussions should begin with patient education about the goals and function of ICDs prior to device placement, namely that these devices do not correct the underlying pathophysiology of heart disease and that deactivation is always an option. 

Unwarranted shocks are clearly distressing for both patients and family members. An episode of firing or increased firings, major changes in health or code status, or near the end of life are all appropriate times to readdress the benefits and burdens of ICDs and how they relate to a patient’s wishes and goals of care. A joint summary statement by the Heart Rhythm Society has been published to assist caregivers and families; there are strong legal and ethical precedents that clearly state withholding of life-saving measures, such as an ICD, is not akin to assisted suicide or euthanasia.³¹ 

In appropriately selected older adults, ICD placement can provide benefits in terms of primary and secondary prevention of SCD and/or ventricular arrhythmias. The decision to place or not place an ICD is complex and should carefully balance potential benefits with risks. Primary care physicians, including geriatricians, should have a basic understanding of the indications for ICD placement in order to refer those patients most likely to benefit from these devices.

Michael Ghannam, MD, is an internal medicine house officer at the University of Michigan Health System in Ann Harbor, MI.

Yasser Rodriguez, MD, MBA, is an internal medicine house officer at the University of Michigan Health System in Ann Harbor, MI. 

Frank Davis, BS, is a medical student at the University of Michigan in Ann Harbor, MI.

Aman Chugh, MD, is an associate professor of internal medicine with a specialty in cardiology at the University of Michigan Health System in Ann Harbor, MI.

Preeti N. Malani, MD, MSJ, is a professor of medicine with a specialty in infectious diseases and geriatrics at the University of Michigan Health System in Ann Harbor, MI.

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