Congestive heart failure (CHF) has become a widespread health concern. The high mortality in CHF has been associated with a high incidence of ventricular arrhythmia and left ventricular (LV) remodeling. Studies have shown that implantable cardioverter defibrillator (ICD) could help lower the rate of sudden cardiac death in patients with CHF. However, this could become a heavy burden for medical health insurance system. To identify high-risk patients is an alternative strategy.

 

Presently, primary prevention of SCD relies on risk stratification based upon left ventricular ejection fraction (LVEF) and degree of congestive heart failure (CHF), followed by implantation of an ICD in patients with LVEF<35% and New York Heart Association Class II–III CHF. Although several clinical trials have demonstrated clear survival benefits conferred by this strategy, the greatest absolute number of SCD occurs in patients with preserved LVEF due to the much larger size of this population.

 

In the past decades, several new parameters based on non-invasive electrophysiology studies have been proposed to predict VT in patients with cardiovascular diseases. The main rationale of these examinations is to evaluate the “electric” factors such as abnormal background autonomic nervous activity or electric instability of the myocardial substrate that play important roles in the generation of VT. For example, parameters based on standard 12-lead ECG or 24h Holter, signal-averaged ECG and heart rate variability. Later, other parameters based on “perturbed” conditions have been developed. These included baroreflex sensitivity (BRS), heart rate recovery (HRR), heart rate turbulence (HRT) and T wave alternans (TWA).

 

Recently, Cardiac magnetic resonance image (CMRI) is another promising modality. Myocardial scar tissue detected by CMRI has been linked to ventricular arrhythmia. Tissue heterogeneity and intra-scar channel identification have been demonstrated to be associated with inducibility of sustained ventricular arrhythmia and to be an independent predictor of post-myocardial infarction (MI) mortality. A combination methods incorporating CMRI in predicting sudden cardiac death will be a routine procedure in the future.