The relationship of prolonged signal-averaged P wave duration to the development of postoperative atrial fibrillation in heart surgery patients

Atrial fibrillation is the most common heart rhythm disorder seen in all types of cardiac disease and is the most common complication associated with all types of heart surgery procedures. It has recently been described as, "a riddle wrapped in a mystery inside an enigma"1 and is estimated to have an annual cost in the U.S. of over {dollar}1 billion due to the increase in hospital length of stay (Steinberg, 2004). Despite over 40 years of research on this problem, the incidence postoperative atrial fibrillation (POAF) remains at 20--40% in coronary artery bypass surgery and as high as 60% in valve surgeries. There is no evidence that this incidence has changed in the past several years, and in fact, some believe it is increasing as the age of individuals undergoing heart operations increase. Options for prevention and treatment carry potential side effects and therefore it would be of significant benefit to be able to predict who is at risk for POAF so that these interventions could be targeted to the high risk individual. There is evidence for a preexisting electrophysiologic substrate in some individuals in the preoperative period, as shown by conduction abnormalities in the high resolution electrocardiogram. The P wave signal-averaged electrocardiogram therefore offers an option for identifying high risk individuals. What is not known, however, is what happens to atrial conduction time after surgery. Knowledge about these changes may provide clues to the factors that trigger this problematic arrhythmia. This study documented the atrial conduction time in the preoperative through postoperative period (day #3) through use of the P-wave signal-averaged electrocardiogram.; 1Steinberg, J. (2004). Postoperativeatrial fibrillation: a billion-dollar problem. J Am Coll Cardiol, 43(6), 1001--1003.