Prevention

• implantable defibrillator ^a  with endocardial leads ^b  

Why?

• It reduces mortality better than anti-arrhythmic drug therapy ^a
• Defibrillators with endocardial leads prevent death more effectively than ones with epicardial leads, but are harder to insert ^b
• However, implantable defibrillators are not clearly more effective than amiodarone and are less cost-effective ^a

Implantable defibrillators reduce mortality compared with conventional therapy

Patient	Treatment	Comparison	Outcome	CER	RRR (95% CI)	NNT (95% CI)
near-fatal ventricular arrhythmia a	implantable defibrillator	amiodarone or sotalol	death at 18 months	24%	34% (15% to 49%)	12 (8 to 30)
previous VT/VF arrest following MI a	implantable defibrillators	conventional therapy	death at 2 years	36%	61% (-8% to 86%)	5 (2 to 150)
recent MI and asymptomatic episode of VT a	implantable defibrillator	conventional therapy	death at 5 years	39%	59% (31% to 76%)	4 (3 to 9)
cardiac arrest or VF b	defibrillator with endocardial leads	defibrillator with epicardial leads	death at 3 years	11%	72% (53% to 83%)	13 (9 to 20)
cardiac arrest or VF	defibrillator with endocardial leads	defibrillator with epicardial leads	successful implantation	99.7%	-13% (-16% to -10%)	-8 (-10 to -6)

Note:

• Half of patients will receive a shock in the next 2 years. (46%: 95% CI: 35% to 56%) This is more likely ^b
  • in women
  • with a low ejection fraction
  • with anti-arrhythmic therapy other than amiodarone