De. Hilleman et Jl. Bauman, Role of antiarrhythmic therapy in patients at risk for sudden cardiac death: An evidence-based review, PHARMACOTHE, 21(5), 2001, pp. 556-575
Sudden cardiac death (SCD) accounts for more than half of all cardiac death
s occurring, each year in the United States. Although it has several causes
, patients at greatest risk are those with coronary artery disease and impa
ired left ventricular function, heart failure secondary to ischemia or idio
pathic Hated cardiomyopathy hypertrophic cardiomyopathy, documented sustain
ed ventricular tachycardia or ventricular fibrillation, and survivors of ca
rdiac arrest. The presence of asymptomatic ventricular arrhythmias, positiv
e signal-averaged electrocardiogram (ECG), low heart rate variability index
, or inducible ventricular tachycardia or ventricular fibrillation increase
s the risk. In primary prevention trials in patients with ischemic heart di
sease, beta -blockers reduced both total mortality and SCD, whereas class I
antiarrhythmic drugs, especially class IC, increased mortality. Among clas
s III agents, d,l-sotalol and dofetilide have a neutral effect on mortality
, whereas d-sotalol increases mortality. Amiodarone has a neutral effect on
total and cardiac mortality but does reduce the risk of arrhythmic death a
nd cardiac arrest. Three primary prevention trials in patients with ischemi
c heart disease were conducted with implantable cardioverter-defibrillators
(ICDs). Patients with low ejection fractions (EFs), asymptomatic ventricul
ar arrhythmias, and inducible ventricular tachycardia. or ventricular fibri
llation had significant reductions in total, cardiac, and arrhythmic death
with ICDs compared with either no drug therapy or conventional antiarrhythm
ic agents. The ICDs did not reduce mortality in patients with low EFs and a
positive signal-averaged ECG undergoing coronary bypass graft. in those wi
th heart failure, beta -blockers reduced total and SCD mortality but dofeti
lide and amiodarone had a neutral effect on mortality. In the secondary pre
vention of SCD, antiarrhythmic drugs alone generally are not thought to imp
rove survival. In three trials in patients with documented sustained ventri
cular tachycardia or ventricular fibrillation, or survivors of SCD, ICDs re
duced cardiac and arrhythmic mortality. Total mortality, however, was signi
ficantly reduced in only one of these trials. The role of antiarrhythmic dr
ugs in secondary prevention of SCD is limited to patients in whom ICD is in
appropriate or in combination with ICD. Antiarrhythmics can be given select
ively with ICDs to decrease episodes of ventricular tachycardia or fibrilla
tion to reduce ICD discharges, to suppress episodes of nonsustained ventric
ular tachycardia that trigger ICD discharges, to slow the rate of ventricul
ar tachycardia to increase hemodynamic stability,, to allow effective antit
achycardia pacing, or to suppress supraventricular arrhythmias.