Risk factors for sudden cardiac death to determine high risk patients in specific patient populations that may benefit from a wearable defibrillator

Table 1 Primary prevention implantable cardioverter defibrillator studies

Study	Intervention/control group	Inclusion criteria	Risk reduction of SCD with ICD
Multicenter Automatic Defibrillator Implantation Trial[12]	ICD vs antiarrhythmic drug	Previous MI; EF ≤ 35%; nsVT; positive findings on EPS	54% (P = 0.001)
Multicenter Unsustained Tachycardia Trial[13]	EP-guided therapy vs placebo	Coronary disease; EF ≤ 40%; Non-sustained VT; inducible VT at EPS	51% (P = 0.001)
Multicenter Automatic Defibrillator Implantation Trial 2[14]	ICD vs optimal pharmacological treatment	Prior MI EF ≤ 30%	31% (P = 0.02)
Sudden Cardiac Death in Heart Failure Trial[15]	ICD vs optimal pharmacological therapy vs optimal pharmacological therapy + amiodarone	Ischaemic and non-ischaemic cardiomyopathy; EF ≤ 35%	23% (P = 0.007)
Defibrillator implantation in patients with nonischemic systolic heart failure[16]	ICD vs optimal pharmacological therapy	Non-ischaemic cardiomyopathy; EF ≤ 35%	50% (P = 0.005)

SCD: Sudden cardiac death; ICD: Implantable cardioverter defibrillator; EF: Ejection fraction; EP: Electrophysiology; MI: Myocardial infarction; EPS: Electrophysiology studies; VT: Ventricular tachycardia.