Table 2. Guidelines for Secondary Prevention ICD Implantation2
Class I*
 Survivors of cardiac arrest due to VF or hemodynamically unstable sustained VT without a reversible cause
 Patients with structural heart disease and spontaneous sustained VT
 Patients with syncope of undetermined cause with sustained VT or VF induced during electrophysiology study
Class IIa*
 Patients with unexplained syncope, significant LV systolic dysfunction, and nonischemic cardiomyopathy
 Patients with sustained VT and normal or near‐normal ventricular function
Class IIb*
 Patients with syncope and advanced structural heart disease in whom thorough invasive and noninvasive investigations have failed to define a cause
Class III
 Not indicated for patients not expected to survive at least 1 year
 Not indicated for patients with incessant VT or VF
 Not indicated for patients with syncope of undetermined cause in a patient without inducible ventricular arrhythmias and no structural heart disease
 Not indicated when VF or VT is amenable to surgical or catheter ablation
 Not indicated for patients with ventricular arrhythmias related to completely reversible disorder in the absence of structural heart disease
  • ICD indicates implantable cardioverter defibrillator; LV, left ventricle; VF, ventricular fibrillation; VT, ventricular tachycardia.

  • *all recommendations for secondary prevention ICD implantation are predicated on “a reasonable expectation of survival with good functional status for more than one year.”2