Treatment and prevention of sudden cardiac death--what have we learnt from randomised clinical trials?
Sudden cardiac death is most commonly caused by ventricular tachycardia or fibrillation. Three groups of patients at highest risk for sudden cardiac death are survivors of previous sudden cardiac death, those with recurrent documented episodes of sustained ventricular tachycardia and patients with recurrent syncope of unknown origin. The experience with antiarrhythmic drugs has been discouraging. Only beta-blockers have been shown to unequivocally reduce both arrhythmic and total mortality in randomised trials. Class I antiarrhythmic drugs increase mortality, especially in an ischemic substrate. Class III drugs such as sotalol and amiodarone have had variable success. Racemic sotalol has both beta-blocker as well as Class III actions and some of the benefits may be due to the former effect. D-sotalol which has only pure Class III action, increases mortality in the post myocardial infarction patient. Amiodarone is superior to Class I antiarrhythmic drugs for patients with previous cardiac arrest. In the high-risk myocardial infarction patient, it seems to reduce sudden death but not total mortality. In the cardiac failure patient, the effect of amiodarone on total mortality is controversial. Several randomised trials of implantable cardioverter-defibrillator (ICD) therapy versus drugs have however concluded that the ICD is superior to drugs in reducing total mortality. In comparison with many other high volume therapies used in medicine today, ICD is still a cost-effective therapy.
Kam
R M
RM
National Heart Centre, Singapore.
Teo
W S
WS
Koh
T H
TH
Lim
Y L
YL
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology / Q000627:therapeutic use; D002986:Clinical Trials as Topic; D003362:Cost-Benefit Analysis; D016757:Death, Sudden, Cardiac / Q000473:pathology*; D017147:Defibrillators, Implantable; D019317:Evidence-Based Medicine; D017048:Health Care Costs; D006801:Humans; D009203:Myocardial Infarction / Q000401:mortality; D011379:Prognosis
D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents