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Sudden cardiac death accounts for
approximately 300000 deaths annually in the US, and most of these are secondary to
malignant ventricular tachyarrhythmias (defined as hypotensive ventricular
tachycardia/ventricular fibrillation) in patients with coronary artery disease.
Most patients with cardiac death die before reaching the hospital, which brought
about a tremendous amount of research focused at identifying patients at high risk.
Management strategy of this problem is centered on two closely related aspects: one,
how to identify those at risk of arrhythmic death (AD), and two, what are the best
therapy management modalities. Several trials were initiated to test the effectiveness
of various therapeutic measures in these high-risk patients. Amiodarone (with or
without beta-blockers) and, particularly, the implantable cardioverter-defibrillator are
considered the two major therapeutic tools to prevent AD in these patients. The high
cost of implantable cardioverter-defibrillator and the invasive nature of this therapeutic
modality limit its widespread use and stress the need for more powerful risk
stratification algorithms for AD.
This article will review the commonly used non-invasive risk stratifiers of AD after
myocardial infarction (MI), including: left ventricular ejection fraction, ventricular
arrhythmias on ambulatory Holter recording, signal averaged electrocardiography
(SAECG), heart rate variability (HRV), baroreflex sensitivity (BRS), QT dispersion and
T wave alternans (TWA). Furthermore the combined use of more than one index of
high risk will be briefly discussed.
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