ICD Indications for Ventricular Tachycardia/Arrest
ICD implantation is recommended for all patients resuscitated from cardiac arrest due to VT/VF and for those with sustained VT causing hemodynamic compromise, as this represents the strongest secondary prevention indication with proven mortality benefit. 1
Secondary Prevention Indications (Strongest Evidence)
Cardiac arrest survivors and sustained VT patients should receive ICDs regardless of underlying etiology:
Patients resuscitated from cardiac arrest due to VT/VF should receive an ICD 1. This applies even after revascularization if abnormal LV function persists or if the arrest was unrelated to acute MI/ischemia 1.
Patients with hemodynamically significant sustained VT require ICD implantation 1. The European Society of Cardiology guidelines classify this as a Class A indication based on multiple randomized trials 1.
Exception: ICDs are NOT recommended if cardiac arrest occurred during acute MI with normal LV function and complete revascularization was achieved 1. This is the only scenario where secondary prevention ICD can be withheld.
Disease-Specific Secondary Prevention
Hypertrophic Cardiomyopathy
- Sudden death survivors and sustained VT patients should receive ICDs 1. Amiodarone has not demonstrated benefit in this population with sustained arrhythmias 1.
- One study showed 65% of HCM patients with prior VT/VF had recurrent events requiring ICD therapy over 5 years 2.
Idiopathic Dilated Cardiomyopathy
- Cardiac arrest survivors and sustained VT patients require ICDs 1. These patients have excellent prognosis with ICD protection since they lack structural coronary disease 1.
Arrhythmogenic Right Ventricular Dysplasia
- Cardiac arrest survivors should receive ICDs 1. For monomorphic VT, antiarrhythmic drugs are first-line, with ICD reserved for drug failure 1.
Primary Prevention Indications
Post-MI with LV Dysfunction
- Non-sustained VT ≥4 days post-MI with LVEF ≤40% and inducible VF/sustained VT at EP study warrants ICD 1. This is a Class B indication based on limited randomized data 1.
Dilated Cardiomyopathy
- LVEF ≤30% with non-sustained VT on Holter monitoring may warrant prophylactic ICD 1. One study showed 37% of such patients received appropriate shocks over 3 years, similar to secondary prevention rates 3.
- Syncope with dilated cardiomyopathy warrants ICD consideration even without inducible arrhythmias, as these patients receive appropriate shocks 1.
Genetic/Inherited Conditions
- Long QT syndrome, hypertrophic cardiomyopathy, ARVD, and Brugada syndrome with high sudden death risk warrant prophylactic ICD 1. Family history of sudden death at young age strengthens this indication 1.
Post-Revascularization Considerations
The 90-day post-revascularization period requires careful assessment:
Secondary prevention patients (prior VT/VF arrest) with abnormal LV function should receive ICDs regardless of revascularization timing 1. The AVID trial showed revascularization did not alter survival benefit of ICDs 1.
If arrest was unrelated to acute ischemia and LV function is normal, ICD is still recommended 1. The arrhythmogenic substrate persists despite revascularization 1.
Primary prevention patients unlikely to improve LVEF >0.35 after revascularization should receive ICDs if not within 40 days of acute MI 1.
Absolute Contraindications
ICDs should NOT be implanted in:
- Terminal illness with life expectancy <6 months 1
- NYHA Class IV heart failure not eligible for transplantation 1
- Severe neurological sequelae following cardiac arrest 1
- Severe hemodynamic compromise without possibility of stabilization unless bridge to transplant 1
Critical Pitfalls
Avoid these common errors:
- Do not withhold ICD from post-revascularization secondary prevention patients based solely on improved LVEF—the arrhythmogenic substrate often persists 1.
- Do not assume revascularization eliminates VT/VF risk; AVID Registry showed similar or worse mortality in "correctable cause" patients treated with revascularization alone 1.
- Recognize that appropriate ICD therapy rates are similar (31-37%) across prophylactic, syncope, and VT/VF groups in dilated cardiomyopathy 3.
- Be aware of high complication rates (45% in one ACHD series, 9% annually) including inappropriate shocks, infections, and lead problems 4.