Abstract
CD is a 68-year-old man who had an anterior myocardial infarction 6 months ago. Evaluation at that time demonstrated an occluded left anterior descending artery, which was successfully stented with no other significant lesions. Left ventricular ejection fraction was 35%. He had no recurrent angina or heart failure symptoms. Early one morning he lost consciousness. Paramedics verified ventricular fibrillation (VF) and provided effective defibrillation within 5 minutes; spontaneous circulation returned before transfer to the hospital. Sudden cardiac death claims 300 000 to 450 000 lives a year in the United States and represents approximately 50% of all cardiac death.1–3⇓⇓ Despite recent declines in age-adjusted cardiac mortality and sudden death risk, the overall incidence has remained relatively stable as our population ages.3 Coronary heart disease is present in the majority (70% to 80%) of patients with sudden death, but cardiac arrest is the first manifestation of this underlying process in 50%.4 Resuscitation rates are very low, averaging from 1% to 3% in most major cities.2,5⇓ There are some data to suggest that focused attempts to reduce the time to effective defibrillation, with improved training of first responders or more widespread availability of automatic external defibrillators, provide some hope for the future. It is a widely held belief that the majority of sudden death events are due to ventricular tachycardia (VT) that degenerates into VF (Figure 1).6 This idea may well reflect our greater experience in observing patients with structural heart disease and prior myocardial infarction. Acute severe ischemia may cause primary polymorphic VT even in the absence of preexisting structural heart disease. Autopsy studies document acute changes in coronary morphology (such as plaque rupture, thrombus, etc) in >50% of sudden death events.7 Severe bradyarrhythmias or electromechanical dissociation probably represent an important …
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