From the Guidelines
Primary Implantable Cardioverter-Defibrillator (ICD) therapy is indicated for patients with left ventricular ejection fraction (LVEF) ≤30% and NYHA class I, II, or III heart failure symptoms, as well as those with LVEF 31%-35% and NYHA class II or III symptoms, and patients with LVEF ≤40% and inducible ventricular tachycardia. The indications for primary ICD implantation are based on the patient's risk of sudden cardiac death due to ventricular arrhythmias.
Key Indications
- Patients with LVEF ≤30% and NYHA class I, II, or III heart failure symptoms are at high risk of sudden cardiac death and benefit from primary ICD implantation 1.
- Patients with LVEF 31%-35% and NYHA class II or III symptoms also benefit from primary ICD implantation 1.
- Patients with LVEF ≤40% and inducible ventricular tachycardia are at increased risk of sudden cardiac death and may benefit from primary ICD implantation 1.
Additional Considerations
- The risk of ventricular arrhythmias and sudden cardiac death is highest early after myocardial infarction, but routine ICD implantation in patients with left ventricular dysfunction early after MI or coronary artery bypass grafting (CABG) has not been associated with improved survival 1.
- Patients with ventricular arrhythmias should first be managed with beta blockers and/or antiarrhythmic therapy, and ICD implantation should be considered in patients who remain at high risk of sudden cardiac death despite optimal medical therapy 1.
- The effects of ICD implantation on mortality cannot be definitely ascertained, and more research is required to determine the optimal timing and patient selection for primary ICD implantation 1.
Guideline Recommendations
- The 2025 ACC/AHA/ACEP/NAEMSP/SCAI guideline recommends primary ICD implantation for patients with LVEF ≤30% and NYHA class I, II, or III heart failure symptoms, as well as those with LVEF 31%-35% and NYHA class II or III symptoms, and patients with LVEF ≤40% and inducible ventricular tachycardia 1.
- The guideline also recommends that patients with ventricular arrhythmias be managed with beta blockers and/or antiarrhythmic therapy, and that ICD implantation be considered in patients who remain at high risk of sudden cardiac death despite optimal medical therapy 1.
From the Research
Indications for Primary Implantable Cardioverter-Defibrillator (ICD)
The indications for a primary Implantable Cardioverter-Defibrillator (ICD) are based on various studies and guidelines. Some of the key indications include:
- Left ventricular ejection fraction (LVEF) ≤ 35% in patients with post-myocardial infarction or nonischemic dilated cardiomyopathy 2
- Significant left ventricular dysfunction in patients with nonischemic dilated cardiomyopathy (NIDCM) 3
- High risk of sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy (HCM) 3
- Patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) or other uncommon familiar cardiomyopathies 3
- Patients with channelopathies such as long QT syndrome (LQTS) or Brugada syndrome 3
Patient Selection Criteria
Patient selection for primary ICD implantation is crucial to improve the benefits of the device. Some of the key criteria include:
- LVEF ≤ 35% 2, 4
- Left ventricular end-diastolic diameter (LVEDD) > 70 mm 5
- Non-sustained ventricular tachycardia (VT) 5
- Long history of disease (> 48 months since diagnosis) 5
- Family history of SCD 5
- Presence of advanced New York Heart Association (NYHA) stage 2
- Impaired renal function 6
- Severely depressed LVEF 6
Risk Stratification
Risk stratification is essential to identify patients who are at high risk of SCD and would benefit from primary ICD implantation. Some of the key risk factors include: