Table 3. ICD for primary prevention of sudden cardiac death.

Class I indications	Contraindications (Class III Indications)
LVEF ≤ 35% due to ischemic or nonischemic cardiomyopathy, at least 40 days post-MI and in NYHA class II or III	Anticipated survival with reasonable functional status < 1 year Significant psychiatric illness that may be aggravated by an ICD Drug refractory NYHA class IV heart failure in patient who is not a candidate for transplantation or CRT-D Syncope of undetermined cause in the absence of structural heart disease or inducible ventricular arrhythmia
LVEF < 30% due to prior MI, at least 40 days post-MI, and NYHA class I
LVEF < 40% due to prior MI with nonsustained VT and inducible sustained VT or VF on electrophysiology study

CRT-D: cardiac resynchronization therapy + defibrillator device; ICD: implantable cardioverter-defibrillator; LVEF: left ventricular ejection fraction; MI: myocardial infarction; NYHA: New York Heart Association; VF: ventricular fibrillation; VT: ventricular tachycardia.