Sudden cardiac death in ischemic heart disease. Pathophysiology and risk stratification

SCD is a major public health problem both at the US and worldwide. It is estimated that each year in the US 400,000– 460,000 persons die of unexpected SCD in Emergency Departments or before reaching a hospital. The current management of SCD is directed at a relatively small percentage of the total population at risk and primarily at those patients already known to be at increased risk by conventional criteria. Pharmaceutical strategies to prevent SCD have been largely ineffective. Because device therapy [implantable cardioverterdefibrillator (ICD)] is designed to rescue patients once an event has already occurred, primary SCD prevention has become one of today’s most critical public health challenges. Current conventional risk stratifiers for SCD have shown low positive predictive power either alone or in different combinations. As of 2005, the main criterion for primary ICD prophylaxis for SCD has been the presence of organic heart disease and depressed left ventricular ejection fraction (LVEF). Unfortunately, depressed LVEF may be a good marker for total cardiac mortality but is not specific for SCD resulting in a significant redundancy of this strategy. The cost to the health care system of sustaining this approach would be substantial. For the immediate future, attempts to optimize the selection process for primary ICD prophylaxis that goes beyond depressed LVEF must continue. The present article will review the most recent pathophysiology and risk stratification of SCD in ischemic heart disease, and its management beyond the current single criterion of depressed LVEF. 2. Coronary artery disease (CAD) and sudden cardiac death (SCD) cascade (Fig. 1)