What are the indications for Implantable Cardioverter-Defibrillator (ICD) placement?

Indications for Implantable Cardioverter-Defibrillator (ICD) Placement

Implantable cardioverter-defibrillators (ICDs) are indicated primarily for patients at high risk of sudden cardiac death due to ventricular tachyarrhythmias, with specific indications based on clinical presentation, cardiac function, and underlying etiology. 1

Primary Indications Based on Clinical Presentation

Class I Indications (Strong Evidence/General Agreement)

• Cardiac arrest survivors: Patients who have experienced circulatory arrest requiring resuscitation due to ventricular fibrillation (VF) or ventricular tachycardia (VT) 1
• Documented ventricular tachycardia: Patients with electrocardiographically documented sustained VT with hemodynamic compromise 1
• Primary prevention in high-risk patients:
  • Previous myocardial infarction with left ventricular ejection fraction (LVEF) ≤30-35% 1
  • Heart failure (NYHA class II-III) with LVEF ≤35% 1

Class II Indications (Conflicting Evidence/Divergence of Opinion)

• Syncope without documented ventricular arrhythmia: Patients with unexplained syncope and inducible ventricular arrhythmias during electrophysiological study 1
• Non-sustained ventricular tachycardia: Patients with coronary artery disease, LVEF ≤40%, and non-sustained VT 1

Indications Based on Specific Cardiac Conditions

Coronary Artery Disease

• Primary prevention for patients with previous MI, LVEF ≤35%, and at least 40 days post-MI 1
• Not indicated in the immediate post-MI period (5-40 days) as shown in DINAMIT and IRIS trials 1

Non-ischemic Cardiomyopathy

• LVEF ≤35% with NYHA class II-III heart failure symptoms 1
• Dilated cardiomyopathy patients with syncope, even without inducible ventricular arrhythmias 1

Hypertrophic Cardiomyopathy

• Survivors of cardiac arrest or sustained ventricular tachyarrhythmias 1, 2
• Consider in patients with family history of sudden cardiac death at young age 1

Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

• High-risk patients who meet task force criteria for ARVD, regardless of electrophysiologic testing results 3
• Both primary and secondary prevention (85% of secondary prevention and 39% of primary prevention patients receive appropriate ICD therapy) 3

Long QT Syndrome and Other Inherited Arrhythmia Syndromes

• Cardiac arrest survivors 1, 4
• Consider in high-risk patients with syncope despite beta-blocker therapy 1, 5

Idiopathic Ventricular Fibrillation

• Indicated in cardiac arrest survivors without identifiable structural heart disease 1, 5

Contraindications for ICD Placement

• Terminal illness with life expectancy <6 months 1
• Significant psychiatric illness that may be aggravated by device implantation 1
• NYHA class IV drug-refractory heart failure in non-transplant candidates 1
• Severe neurological sequelae following cardiac arrest 1
• Ventricular arrhythmias due to reversible causes (acute ischemia, electrolyte abnormalities) 1

Important Considerations

• ICD therapy has drawbacks including device dependence, implantation complications, inappropriate shocks, and driving restrictions 1
• Alternative treatments should always be considered, including antiarrhythmic drugs, catheter ablation, and surgical interventions 1
• Even patients with normal LVEF may be appropriate candidates in specific conditions like idiopathic VF 1
• Pediatric and young adult patients with inherited arrhythmia syndromes can benefit from ICDs, with appropriate successful discharges observed in patients previously resuscitated from SCD 4

The decision to implant an ICD requires careful assessment of risk-benefit ratio, considering both mortality reduction and potential complications of device therapy. The strongest evidence supports ICD use in survivors of cardiac arrest and in primary prevention for patients with significantly reduced left ventricular function.