Pacing

Permanent Pacing in Sinus Node Dysfunction (SND)

Key Points

• SND refers to a broad array of abnormalities in sinus node and atrial impulse formation and propagation.
  • These include persistent sinus bradycardia and chronotropic incompetence without identifiable causes, paroxysmal or persistent sinus arrest with replacement by subsidiary escape rhythms in the atrium, atrioventricular (AV) junction, or ventricular myocardium.
  • The frequent association of paroxysmal atrial fibrillation (AF) and sinus bradycardia or sinus bradyarrhythmias, which may oscillate suddenly from one to the other, usually accompanied by symptoms, is termed “tachy-brady syndrome.”
  • SND is primarily a disease of the elderly and is presumed to be due to senescence of the sinus node and atrial muscle.
• The clinical manifestations of SND are diverse, reflecting the range of typical sinoatrial rhythm disturbances.
  • The most dramatic presentation is syncope.
  • However, in many patients, the clinical manifestations of SND are more insidious and relate to an inadequate heart rate response to activities of daily living that can be difficult to diagnose.
  • The term “chronotropic incompetence” is used to denote an inadequate heart rate response to physical activity.
• No single metric has been established as a diagnostic standard upon which therapeutic decisions can be based.
• The only effective treatment for symptomatic bradycardia is permanent cardiac pacing.
• The optimal pacing system for prevention of symptomatic bradycardia in SND is unknown.

Treatment

• Permanent pacemaker implantation is indicated for:
  • SND with documented symptomatic bradycardia, including frequent sinus pauses that produce symptoms. (I-C)
  • Symptomatic chronotropic incompetence. (I-C)
  • Symptomatic sinus bradycardia that results from required drug therapy for medical conditions. (I-C)
• Permanent pacemaker implantation is reasonable for:
  • SND with heart rate <40 bpm when a clear association between significant symptoms consistent with bradycardia and the actual presence of bradycardia has not been documented. (IIa-C)
  • Syncope of unexplained origin when clinically significant abnormalities of sinus node function are discovered or provoked in electrophysiological studies. (IIa-C)
• Permanent pacemaker implantation may be considered in:
  • Minimally symptomatic patients with chronic heart rate <40 bpm while awake. (IIb-C)
• Permanent pacemaker implantation is NOT indicated for SND:
  • In asymptomatic patients. (III-C)
  • In patients for whom the symptoms suggestive of bradycardia have been clearly documented to occur in the absence of bradycardia. (III-C)
  • With symptomatic bradycardia due to nonessential drug therapy. (III-C)

Figure 1. Sinus Node Dysfunction

Acquired Atrioventricular (AV) Block in Adults

Key Points

• Patients with abnormalities of AV conduction may be asymptomatic or may experience serious symptoms related to bradycardia, ventricular arrhythmias, or both.
• AV block can sometimes be provoked by exercise.
• Type I second-degree AV block is characterized by progressive prolongation of the PR interval before a nonconducted beat and a shorter PR interval after the blocked beat.
• Type I second-degree AV block is usually due to delay in the AV node irrespective of QRS width.

Because progression to advanced AV block in this situation is uncommon, pacing is usually not indicated unless the patient is symptomatic.

• Type II second-degree AV block is characterized by fixed PR intervals before and after blocked beats and is usually associated with a wide QRS complex.
• Type II second-degree AV block is usually infranodal (either intra- or infra-His), especially when the QRS is wide.

In these patients, symptoms are frequent, prognosis is compromised, and progression to third-degree AV block is common and sudden. Thus, type II second-degree AV block with a wide QRS typically indicates diffuse conduction system disease and constitutes an indication for pacing even in the absence of symptoms.

• When AV conduction occurs in a 2:1 pattern, block cannot be classified unequivocally as type I or type II, although the width of the QRS can be suggestive.
• Advanced second-degree AV block refers to the blocking of ≥2 consecutive P waves with some conducted beats, which indicates some preservation of AV conduction.

In the setting of AF, a prolonged pause (eg, >5 seconds) should be considered to be due to advanced second-degree AV block.

• Third-degree AV block (complete heart block) is defined as absence of AV conduction.
• In a patient with third-degree AV block, permanent pacing should be strongly considered even when the ventricular rate is >40 bpm, because the choice of a 40 bpm cutoff in these guidelines was not determined from clinical trial data.

Indeed, it is not the escape rate that is necessarily critical for safety but rather the site of origin of the escape rhythm (ie, in the AV node, the His bundle, or infra-His).

Treatment

• Permanent pacemaker implantation is indicated for:
  • Third-degree and advanced second-degree AV block at any anatomic level:
    • Associated with bradycardia with symptoms (including heart failure [HF]) or ventricular arrhythmias presumed to be due to AV block. (I-C)
    • Associated with arrhythmias and other medical conditions that require drug therapy that results in symptomatic bradycardia. (I-C)
    • In awake, symptom-free patients in sinus rhythm, with documented periods of asystole ≥3.0 seconds or any escape rate <40 bpm, or with an escape rhythm that is below the AV node. (I-C)
    • In awake, symptom-free patients with AF and bradycardia with one or more pauses of at least 5 seconds or longer. (I-C)
    • After catheter ablation of the AV junction. (I-C)
    • Associated with postoperative AV block that is not expected to resolve after cardiac surgery. (I-C)
    • Associated with neuromuscular diseases with AV block, such as myotonic muscular dystrophy, Kearns-Sayre syndrome, Erb dystrophy (limb-girdle muscular dystrophy), and peroneal muscular atrophy, with or without symptoms. (I-B)
  • Second-degree AV block with associated symptomatic bradycardia regardless of type or site of block. (I-B)
  • Asymptomatic persistent third-degree AV block at any anatomic site with average awake ventricular rates of ≥40 bpm if cardiomegaly or left ventricular (LV) dysfunction is present or if the site of block is below the AV node. (I-B)
  • Second- or third-degree AV block during exercise in the absence of myocardial ischemia. (I-C)
• Permanent pacemaker implantation is reasonable for:
  • Persistent third-degree AV block with an escape rate >40 bpm in asymptomatic adult patients without cardiomegaly. (IIa-C)
  • Asymptomatic second-degree AV block at intra- or infra-His levels found at electrophysiological study. (IIa-B)
  • First- or second-degree AV block with symptoms similar to those of pacemaker syndrome or hemodynamic compromise. (IIa-B)
  • Asymptomatic type II second-degree AV block with a narrow QRS.

When type II second-degree AV block occurs with a wide QRS, including isolated right bundle-branch block, pacing becomes a Class I recommendation. (See “Permanent Pacing in Chronic Bifascicular Block.”) (IIa-B)

• Permanent pacemaker implantation may be considered for:
  • Neuromuscular diseases such as myotonic muscular dystrophy, Erb dystrophy (limb-girdle muscular dystrophy), and peroneal muscular atrophy with any degree of AV block (including first-degree AV block), with or without symptoms, because there may be unpredictable progression of AV conduction disease. (IIb-B)
  • AV block in the setting of drug use and/or drug toxicity when the block is expected to recur even after the drug is withdrawn. (IIb-B)

• Permanent pacemaker implantation is NOT indicated for:
  • Asymptomatic first-degree AV block. (III-B) (See “Permanent Pacing in Chronic Bifascicular Block.”)
  • Asymptomatic type I second-degree AV block at the supra-His (AV node) level or that which is not known to be intra- or infra-Hisian. (III-C)
  • AV block that is expected to resolve and is unlikely to recur (eg, drug toxicity, Lyme disease, or transient increases in vagal tone or during hypoxia in sleep apnea syndrome in the absence of symptoms). (III-B)

Permanent Pacing in Chronic Bifascicular Block

Key Points

• Bifascicular block refers to ECG evidence of impaired conduction below the AV node in the right and left bundles.

Alternating bundle-branch block (also known as bilateral bundle-branch block) refers to situations in which clear ECG evidence for block in all 3 fascicles is manifested on successive ECGs.

• Patients with first-degree AV block in association with bifascicular block and symptomatic, advanced AV block have a high mortality rate and a substantial incidence of sudden death.
• Syncope is common in patients with bifascicular block, but it is not associated with an increased incidence of sudden death.

Therefore, pacing relieves the neurological symptoms but does not reduce the occurrence of sudden death.

• Ventricular arrhythmias are common in patients with bifascicular block.

Treatment

• Permanent pacemaker implantation is indicated for:
  • Advanced second-degree AV block or intermittent third-degree AV block. (I-B)
  • Type II second-degree AV block. (I-B)
  • Alternating bundle-branch block. (I-C)
• Permanent pacemaker implantation is reasonable for:
  • Syncope not demonstrated to be due to AV block when other likely causes have been excluded, specifically ventricular tachycardia (VT). (IIa-B)
  • An incidental finding at electrophysiological study of a markedly prolonged
    His to ventricle interval (≥100 milliseconds) in asymptomatic patients. (IIa-B)
  • An incidental finding at electrophysiological study of pacing-induced infra-His block that is not physiological. (IIa-B)
• Permanent pacemaker implantation may be considered:
  • In the setting of neuromuscular diseases such as myotonic muscular dystrophy, Erb dystrophy (limb-girdle muscular dystrophy), and peroneal muscular atrophy with bifascicular block or any fascicular block, with or without symptoms. (IIb-C)
• Permanent pacemaker implantation is NOT indicated for:
  • Fascicular block without AV block or symptoms. (III-B)
  • Fascicular block with first-degree AV block without symptoms. (III-B)

Permanent Pacing in Hypersensitive Carotid Sinus Syndrome and Neurocardiogenic Syncope

Key Points

• The hypersensitive carotid sinus syndrome is defined as syncope or presyncope resulting from an extreme reflex response to carotid sinus stimulation. There are 2 components of the reflex:
  • Cardioinhibitory, which results from increased parasympathetic tone and is manifested by slowing of the sinus rate or prolongation of the PR interval and advanced AV block, alone or in combination.
  • Vasodepressor, which is secondary to a reduction in sympathetic activity that results in loss of vascular tone and hypotension.

This effect is independent of heart rate changes.

• Hyperactive response to carotid sinus stimulation is defined as asystole due to either sinus arrest or AV block of >3 seconds, a substantial symptomatic decrease in systolic blood pressure, or both.
• Permanent pacing for patients with an excessive cardioinhibitory response to carotid stimulation is effective in relieving symptoms.
• Because 10%-20% of patients with this syndrome may have an important vasodepressive component of their reflex response, it is desirable that this component be defined before one concludes that all symptoms are related to asystole alone.

Among patients whose reflex response includes both cardioinhibitory and vasodepressive components, attention to the latter is essential for effective therapy in patients undergoing pacing.

Treatment

• Permanent pacing is indicated:
  • For recurrent syncope caused by spontaneously occurring carotid sinus stimulation and carotid sinus pressure that induces ventricular asystole of >3 seconds. (I-C)
• Permanent pacing is reasonable for:
  • Syncope without clear, provocative events and with a hypersensitive cardioinhibitory response of ≥3 seconds. (IIa-C)
• Permanent pacing may be considered for:
  • Significantly symptomatic neurocardiogenic syncope associated with bradycardia documented spontaneously or at the time of tilt-table testing. (IIb-B)
• Permanent pacing is NOT indicated for:
  • A hypersensitive cardioinhibitory response to carotid sinus stimulation without symptoms or with vague symptoms. (III-C)
  • Situational vasovagal syncope in which avoidance behavior is effective and preferred. (III-C)

Pacing After Cardiac Transplantation

Key Point

• The incidence of bradyarrhythmias after cardiac transplantation varies from 8% to 23%.

Treatment

• Permanent pacing is indicated for:
  • Persistent inappropriate or symptomatic bradycardia not expected to resolve and for other Class I indications for permanent pacing. (I-C)
• Permanent pacing may be considered:
  • When relative bradycardia is prolonged or recurrent, which limits rehabilitation or discharge after postoperative recovery from cardiac transplantation. (IIb-C)
  • For syncope after cardiac transplantation even when bradyarrhythmia has not been documented. (IIb-C)

Pacing to Prevent Tachycardia

Treatment

• Permanent pacing is indicated for:
  • Sustained pause-dependent VT, with or without QT prolongation. (I-C)
• Permanent pacing is reasonable for:
  • High-risk patients with congenital long-QT syndrome. (IIa-C)
• Permanent pacing may be considered for:
  • Prevention of symptomatic, drug-refractory, recurrent AF in patients with coexisting SND. (IIb-B)
• Permanent pacing is NOT indicated for:
  • Frequent or complex ventricular ectopic activity without sustained VT in the absence of the long-QT syndrome. (III-C)
  • Forsade de pointes VT due to reversible causes. (III-A)

Pacing to Prevent Atrial Fibrillation

Treatment

• Permanent pacing is NOT indicated for:
  • The prevention of AF in patients without any other indication for pacemaker implantation. (III-B)

Cardiac Resynchronization Therapy (CRT)

Key Points

• Progression of LV systolic dysfunction to clinical HF is frequently accompanied by impaired electromechanical coupling, which may further diminish effective ventricular contractility.
  • The most common disruptions are prolonged AV (first-degree AV block) and prolonged interventricular conduction, most commonly left bundle-branch block (LBBB).
  • Prolonged interventricular and intraventricular conduction causes regional mechanical delay within the left ventricle that can result in reduced ventricular systolic function, altered myocardial metabolism, functional mitral regurgitation, and adverse remodeling with ventricular dilatation.
  • Prolongation of the QRS duration occurs in approximately one-third of patients with advanced HF and has been associated with ventricular electromechanical delay (“dyssynchrony”).
• QRS duration and dyssynchrony both have been identified as predictors of worsening HF, sudden cardiac death (SCD), and total death.
• Modification of ventricular electromechanical delay with multisite ventricular pacing (commonly called “biventricular pacing” or CRT) can improve ventricular systolic function, reduce metabolic costs, ameliorate functional mitral regurgitation, and, in some patients, induce favorable remodeling with reduction of cardiac chamber dimensions.

Treatment

• CRT is indicated for:
  • Patients who have left ventricular ejection fraction (LVEF) ≤35%, sinus rhythm, LBBB with a QRS duration ≥150 ms, and NYHA class II, III, or ambulatory IV; symptoms on guideline-directed medical therapy (GDMT).
    (I-A for NYHA III/IV; I-B for NYHA II)
• CRT can be useful for patients on GDMT who have LVEF ≤35%:
  • Sinus rhythm, LBBB with a QRS duration 120-149 ms, and NYHA class II, III, or ambulatory IV symptoms. (IIa-B)
  • Sinus rhythm, a non-LBBB pattern with a QRS duration ≥150 ms, and NYHA class III/ambulatory class IV symptoms. (IIa-A)
  • With AF if: (IIa-B)
    • the patient requires ventricular pacing or otherwise meets CRT criteria and
    • AV nodal ablation or pharmacologic rate control will allow near 100% ventricular pacing with CRT.
  • And are undergoing new or replacement device placement with anticipated requirement for significant (>40%) ventricular pacing. (IIa-C)
• CRT may be considered for patients who have:
  • LVEF ≤30%, ischemic etiology of HF, sinus rhythm, LBBB with a QRS duration ≥150 ms, and NYHA class I symptoms on GDMT. (IIb-C)
  • LVEF ≤35%, sinus rhythm, a non-LBBB pattern with a QRS duration 120-149 ms, and NYHA class III/ambulatory class IV on GDMT. (IIb-B)
  • LVEF ≤35%, sinus rhythm, a non-LBBB pattern with a QRS duration ≥150 ms, and NYHA class II symptoms on GDMT. (IIb-B)
• CRT is NOT recommended for patients:
  • With NYHA class I or II symptoms and non-LBBB pattern with QRS duration
    <150 ms. (III-B: No Benefit)
  • Whose comorbidities and/or frailty limit survival with good functional capacity to <1 year. (III-C: No Benefit)

Permanent Pacing in Children, Adolescents, and Patients With Congenital Heart Disease

Key Points

• The most common indications for permanent pacemaker implantation in children, adolescents, and patients with congenital heart disease may be classified as:
  • Symptomatic sinus bradycardia
  • The bradycardia-tachycardia syndromes
  • Advanced second- or third-degree AV block, either congenital or postsurgical.

Treatment

• Permanent pacemaker implantation is indicated for:
  • Advanced second- or third-degree AV block associated with symptomatic bradycardia, ventricular dysfunction, or low cardiac output. (I-C)
  • SND with correlation of symptoms during age-inappropriate bradycardia. (I-B)

The definition of bradycardia varies with the patient’s age and expected heart rate.

• Postoperative advanced second- or third-degree AV block that is not expected to resolve or that persists ≥7 days after cardiac surgery. (I-B)
• Congenital third-degree AV block with a wide QRS escape rhythm, complex ventricular ectopy, or ventricular dysfunction. (I-B)
• Congenital third-degree AV block in the infant with a ventricular rate <55 bpm or with congenital heart disease and a ventricular rate <70 bpm. (I-C)

• Permanent pacemaker implantation is reasonable for:
  • Patients with congenital heart disease and sinus bradycardia for the prevention of recurrent episodes of intra-atrial reentrant tachycardia.

  SND may be intrinsic or secondary to antiarrhythmic treatment.IIa-C

  • Congenital third-degree AV block beyond the first year of life with an average heart rate <50 bpm, abrupt pauses in ventricular rate that are 2 or 3 times the basic cycle length, or associated with symptoms due to chronotropic incompetence. (IIa-B)
  • Sinus bradycardia with complex congenital heart disease with a resting heart rate
    <40 bpm or pauses in ventricular rate >3 seconds. (IIa-C)
  • Patients with congenital heart disease and impaired hemodynamics due to sinus bradycardia or loss of AV synchrony. (IIa-C)
  • Unexplained syncope in the patient with prior congenital heart surgery complicated by transient complete heart block with residual fascicular block after a careful evaluation to exclude other causes of syncope. (IIa-B)
• Permanent pacemaker implantation may be considered for:
  • Transient postoperative third-degree AV block that reverts to sinus rhythm with residual bifascicular block. (IIb-C)
  • Congenital third-degree AV block in asymptomatic children or adolescents with an acceptable rate, a narrow QRS complex, and normal ventricular function. (IIb-B)
  • Asymptomatic sinus bradycardia after biventricular repair of congenital heart disease with a resting heart rate <40 bpm or pauses in ventricular rate >3 seconds. (IIb-C)
• Permanent pacemaker implantation is NOT indicated for:
  • Transient postoperative AV block with return of normal AV conduction in the otherwise asymptomatic patient. (III-B)
  • Asymptomatic bifascicular block with or without first-degree AV block after surgery for congenital heart disease in the absence of prior transient complete AV block. (III-C)
  • Asymptomatic type I second-degree AV block. (III-C)
  • Asymptomatic sinus bradycardia with the longest relative risk interval <3 seconds and a minimum heart rate >40 bpm. (III-C)

Implantable Cardioverter-Defibrillator (ICD)

Key Points

• The options for management of patients with ventricular arrhythmias include antiarrhythmic agents, catheter ablation, and surgery.
• Patient selection, device and lead implantation, follow-up, and replacement are parts of a complex process that requires familiarity with device capabilities, adequate case volume, continuing education, and skill in the management of ventricular arrhythmias, thus mandating appropriate training and credentialing.

Treatment

• ICD therapy is indicated in patients:
  • Who are survivors of cardiac arrest due to ventricular fibrillation (VF) or hemodynamically unstable sustained VT after evaluation to define the cause of the event and to exclude any completely reversible causes. (I-A)
  • With structural heart disease and spontaneous sustained VT, whether hemodynamically stable or unstable. (I-B)
  • With syncope of undetermined origin with clinically relevant, hemodynamically significant sustained VT or VF induced at electrophysiological study. (I-B)
  • With LVEF ≤35% due to prior MI who are ≥40 days post-MI and are in NYHA functional class II or III. (I-A)
  • With nonischemic dilated cardiomyopathy (DCM) who have an LVEF ≤35% and who are in NYHA functional class II or III. (I-B)
  • With LV dysfunction due to prior MI who are ≥40 days post-MI, have an LVEF
    ≤30%, and are in NYHA functional class I. (I-A)
  • With nonsustained VT due to prior MI, LVEF ≤40%, and inducible VF or sustained VT at electrophysiological study. (I-B)
• ICD implantation is reasonable:
  • For patients with unexplained syncope, significant LV dysfunction, and nonischemic DCM. (IIa-C)
  • For patients with sustained VT and normal or near-normal ventricular function. (IIa-C)
  • For patients with HCM who have ≥1 major risk factors for SCD. (IIa-C)
  • For the prevention of SCD in patients with arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy who have ≥1 risk factors for SCD. (IIa-C)
  • To reduce SCD in patients with long-QT syndrome who are experiencing syncope and/or VT while receiving beta blockers. (IIa-B)
  • For nonhospitalized patients awaiting transplantation. (IIa-C)
  • For patients with Brugada syndrome who have had syncope. (IIa-C)
  • For patients with Brugada syndrome who have documented VT that has not resulted in cardiac arrest. (IIa-C)
  • For patients with catecholaminergic polymorphic VT who have syncope and/or documented sustained VT while receiving beta blockers. (IIa-C)
  • For patients with cardiac sarcoidosis, giant cell myocarditis, or Chagas disease. (IIa-C)
• ICD therapy may be considered in patients:
  • With nonischemic heart disease who have an LVEF of ≤35% and who are in NYHA functional class I. (IIb-C)
  • With long-QT syndrome and risk factors for SCD. (IIb-B)
  • With syncope and advanced structural heart disease in whom thorough invasive and noninvasive investigations have failed to define a cause. (IIb-C)
  • With a familial cardiomyopathy associated with sudden death. (IIb-C)
  • With LV noncompaction. (IIb-C)
• ICD therapy is NOT indicated:
  • For patients who do not have a reasonable expectation of survival with an acceptable functional status for ≥1 year, even if they meet ICD implantation criteria specified in the Class I, IIa, and IIb recommendations above. (III-C)
  • For patients with incessant VT or VF. (III-C)
  • For patients with significant psychiatric illnesses that may be aggravated by device implantation or that may preclude systematic follow-up. (III-C)
  • For NYHA class IV patients with drug-refractory congestive HF who are not candidates for cardiac transplantation or CRT defibrillator (CRT-D). (III-C)
  • Syncope of undetermined cause in a patient without inducible ventricular tachyarrhythmias and without structural heart disease. (III-C)
  • When VF or VT is amenable to surgical or catheter ablation (eg, atrial arrhythmias associated with the Wolff-Parkinson-White syndrome, RV or LV outflow tract VT, idiopathic VT, or fascicular VT in the absence of structural heart disease). (III-C)
  • For patients with ventricular tachyarrhythmias due to a completely reversible disorder in the absence of structural heart disease (eg, electrolyte imbalance, drugs, or trauma). (III-B)

Table 1. Minimum Frequency of Cardiovascular Implantable Electronic Devices (CIEDs) In-Person or Remote Monitoringa

Type and Frequency/Method

Pacemaker/ICD/CRT

Within 72 h of CIED implantation

In person

2-12 wk postimplantation

In person

Every 3-12 mo for pacemaker/CRT-Pacemaker

In person or remote

Every 3-6 mo for ICD/CRT-D

In person or remote

Annually until battery depletion

In person

Every 1-3 mo at signs of battery
depletion

In person or remote

Implantable loop recorder

Every 1-6 mo depending on patient symptoms and indication

In person or remote

Implantable hemodynamic monitor

Every 1-6 mo depending on indication

In person or remote

More frequent assessment as clinically indicated

In person or remote

^a More frequent in-person or remote monitoring may be required for all the above devices as clinically indicated.
Modified from Wilkoff B et al. Heart Rhythm 2008;5(6):907–25.

Figure 2. Indications for Cardiac Resychronization Therapy

Table 2. Choice of Pacemaker Generator in Selected Indications for Pacing

Recommendation Grading

Abbreviations

ACCF, American College of Cardiology Foundation; AF, atrial fibrillation; AHA, American Heart Association; AMI, acute myocardial infarction; AV, atrioventricular; CIED, cardiovascular implantable electronic device; CRT, cardiac resynchronization therapy; CRT-D, cardiac resynchronization therapy defibrillator; CRT-Pacemaker, cardiac resynchronization therapy pacemaker; DCM, dilated cardiomyopathy; ECG, electrocardiograph; GDMT, guideline-directed medical therapy; h, hour; HCM, hypertrophic cardiomyopathy; HF, heart failure; ICD, implantable cardioverter-defibrillator; LBBB, left bundle-branch block; LV, left ventricular; LVEF, left ventricle ejection fraction; MI, myocardial infarction; mo, month; ms, millisecond; NYHA, New York Heart Association; RV, right ventricular; SCD, sudden cardiac death; SND, sinus node dysfunction; SVT, supraventricular tachycardia; VF, ventricular fibrillation; VT, ventricular tachycardia; wk, week; y, year

Sources

Tracy CM, Epstein AE, Darbar D, et al. 2012 ACCF/AHA/HRS Focused Update Incorporated Into the ACCF/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. Published online December 19, 2012. doi:10.1016/j.jacc.2012.11.007.

Tracy CM, Epstein AE, Darbar D, et al. 2012 ACCF/AHA/HRS Focused Update Incorporated Into the ACCF/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. Circulation. 2012; published online before print December 19 2012, doi:10.1161/CIR.0b013e318276ce9b9b

Disclaimer

This Guideline attempts to define principles of practice that should produce high-quality patient care. It is applicable to specialists, primary care, and providers at all levels. This Guideline should not be considered exclusive of other methods of care reasonably directed at obtaining the same results. The ultimate judgment concerning the propriety of any course of conduct must be made by the clinician after consideration of each individual patient situation.

Neither IGC, the medical associations, nor the authors endorse any product or service associated with the distributor of this clinical reference tool.