Implantable defibrillator therapy

Sudden cardiac death (SCD) is the most important cause of death in the industrialised world. Treatment with antiarrhythmic drugs (AAD), however, proved disappointing in preventing SCD. From drugs with electrophysiological properties, only treatment with beta-blockers has been shown to improve clinical outcome. This lack of efficiency of AADs heralded a new era of secondary and primary prevention trials, comparing implantable cardioverterdefibrillator (ICD) with drug therapy. Three large randomised secondary prevention trials were conducted in patients with prior myocardial infarction who where resuscitated from VT or VF. Meta-analysis of these three studies show consistent ICD benefit. This ICD benefit is also observed in three large randomised primary prevention trials in patients with a prior myocardial infarction and left ventricular dysfunction. The beneficial effect of ICD therapy proves to be significantly more pronounced in patients with the lowest left ventricular ejection fraction (26-30%). In patients with nonischaemic dilated cardiomyopathy and low ejection fractions, however, currently the only evidence-based indication for ICD implantation is secondary prevention.