Atrial fibrillation is not benign: all patients, even without underlying heart disease, ultimately develop left ventricular dysfunction. Despite theoretical advantages for rhythm control over rate control, of the four recent randomized trials, one showed a trend for lower mortality with rate control while the other three found no difference. However the trials excluded the highly symptomatic arrhythmic patients who are typically younger and, in half the cases, have no associated cardiovascular condition. The trials also omitted to show how sinus rhythm would have influenced morbidity and mortality had it been maintained in more patients. Restoration of sinus rhythm with cardioversion and antiarrhythmic prophylaxis or other nonpharmacologic interventions remains mandatory in such patients. Safer and more effective rhythm control methods would cover an important unmet need...