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

Indications for ICD Insertion

Implantable Cardioverter-Defibrillator (ICD) insertion is indicated for patients with high risk of sudden cardiac death due to ventricular tachyarrhythmias, including those with prior cardiac arrest, sustained ventricular tachycardia with hemodynamic compromise, and those with reduced left ventricular ejection fraction ≤35-40% despite optimal medical therapy. 1

Primary Prevention Indications

• Left ventricular dysfunction with LVEF ≤35-40%:

  • Ischemic cardiomyopathy patients with LVEF ≤35% 1
  • Non-ischemic cardiomyopathy patients with LVEF ≤35% 1
  • Non-sustained ventricular tachycardia ≥4 days after myocardial infarction with LVEF ≤40% and inducible VF or sustained VT at electrophysiological study 1

• High-risk genetic/inherited conditions:

  • Hypertrophic cardiomyopathy with high risk features 1, 2
  • Arrhythmogenic right ventricular dysplasia/cardiomyopathy 1
  • Long QT syndrome with high risk features 1, 2
  • Brugada syndrome with high risk features 1
  • Other genetic disorders with established high risk for sudden cardiac death 1

Secondary Prevention Indications

• Cardiac arrest survivors: Patients who have survived cardiac arrest due to ventricular tachycardia (VT) or ventricular fibrillation (VF) not due to a reversible cause 1

• Documented sustained ventricular tachyarrhythmias:

  • Sustained VT with severe hemodynamic compromise (syncope, near-syncope, heart failure, shock, or angina) 1
  • Sustained VT without hemodynamic compromise in patients with LVEF ≤40% 1

Special Circumstances

• Post-revascularization patients:

  • Patients who have previously qualified for ICD for secondary prevention likely related to myocardial ischemia/injury with abnormal LV function should receive an ICD even after revascularization 1
  • Patients with normal LV function where cardiac arrest was likely related to myocardial ischemia that has been revascularized may benefit from ICD 1
  • Patients within 90 days of revascularization who require non-elective permanent pacing, meet primary prevention criteria, and have uncertain or unlikely recovery of LV function should receive an ICD with appropriate pacing capabilities 1

• Patients with pacemaker indications:

  • Patients requiring permanent pacing who also meet criteria for ICD should receive a device with both capabilities rather than a staged approach (which increases complication risk) 1

Contraindications

• Terminal illness: VT/VF associated with terminal illness with projected life expectancy <6 months 1
• Psychiatric illness: Significant psychiatric illness that may be aggravated by device implantation or preclude systematic follow-up 1
• End-stage heart failure: NYHA class IV drug-refractory heart failure in patients who are not candidates for cardiac transplantation 1
• Severe neurological sequelae: Patients with severe neurological damage following cardiac arrest 1
• Transient/reversible causes: VT/VF due to completely reversible causes (e.g., within 48 hours of acute MI, acute ischemia, or WPW syndrome) 1

Important Clinical Considerations

• The benefit of ICD therapy is most established in patients with reduced left ventricular function (LVEF ≤35-40%)
• For patients undergoing CABG surgery, prophylactic ICD implantation is not recommended unless they meet other criteria 1
• When choosing between single, dual, or biventricular systems, consider the clinical setting, current guidelines, and patient preference 1
• Complications of ICD implantation include inappropriate shocks, infection risk, and the need for device or lead replacement 3
• The subcutaneous ICD (S-ICD) may be considered for patients with prior device infection, difficult venous access, active lifestyles, or young patients who may outlive transvenous ICD leads, but is contraindicated in patients requiring pacing 4

The evidence strongly supports ICD use in both primary and secondary prevention of sudden cardiac death in appropriately selected patients, with multiple randomized trials demonstrating mortality benefit compared to medical therapy alone 3, 5, 6.