Sudden Cardiac Death In Coronary Artery Disease

Sudden cardiac death (SCD) is defined as unexpected natural death from a cardiac cause that occurs spontaneously or within 1 h after an abrupt change in clinical status in a person who did not already have a condition that appeared to be fatal. Sudden cardiac death is the leading cause of death worldwide. Every year, approximately four to five million SCDs are estimated to occur worldwide, which corresponds to approximately 50 % of all deaths from coronary artery disease (CAD). Coronary artery disease accounts for 80 % of all SCDs, and both CAD and SCD are associated with risk factors such as family history of CAD, hypertension, diabetes mellitus, male sex, old age, cigarette smoking, hypercholesterolemia, kidney dysfunction, and obesity. There has been a decline in the incidence of SCD that mirrors the national decline in coronary artery disease (CAD) mortality.The incidence of SCD increases with age in both men and women. The annual incidence of SCD is three to four times higher in men than in women; approximately 75 % of SCDs occur in men. Social isolation, stress at work, depression, anxiety, marital problems, death of a child, caring for a sick spouse, and childhood abuse have been associated with an increased risk of cardiovascular mortality. The majority of patients who have an SCD do not have symptoms and are not identified as being at high risk before the event. Therefore, in addition to the secondary prevention of SCD (i.e., prevention of recurrent cardiac arrest), primary prevention is a major therapeutic goal. Left ventricular ejection fraction (LVEF) is a strong predictor of subsequent SCD. Despite its less-than-optimal sensitivity and specificity, LVEF is the cornerstone of decision-making regarding primary prevention of SCD. Patients with an LVEF of less than 30-35 % are considered to be at high risk and qualify for primary prevention with an implantable cardioverter-defibrillator (ICD). Current practice guidelines recommend assessing LV function 40 days after myocardial infarction to determine the necessity of ICD implantation for primary prevention of SCD.