Electrical Alternans and Vulnerability to Ventricular Arrhythmias

Although electrical alternans (alternating amplitude from beat to beat on the electrocardiogram) has remained an electrocardiographic curiosity for more than three quarters of a century, 1 – 4 we have only recently recognized that it can be a harbinger of sudden cardiac death 5 – 7 . Electrical alternans can precede ventricular fibrillation in patients undergoing coronary angioplasty 8 or those with Prinzmetal's angina, 9 , 10 the congenital prolonged QT syndrome, 5 , 11 acute myocardial infarction, 12 , 13 catecholamine excess, 14 , 15 and electrolyte derangements 16 , 17 . These reports, though numerous, are largely anecdotal, and the prevalence and prognostic importance of alternans among the patients with these conditions or . . .