An irregular heartbeat might be linked with a more serious medical condition such as Atrial Fibrillation (AF), the most common type of heart arrhythmia in the United States. Professors and physicians at Stanford University Medical Center stress the importance of early diagnosis and appropriate treatment for a number of cardiac arrhythmias that affect more than 2 million Americans. What is the difference between a benign palpitation and a life-threatening affliction?