AAF is a multifactorial disease involving structural cardiac abnormalities, inflammation, electrolyte disturbances, hormonal and autonomous nervous system dysregulation, and fluid imbalance, among others, as underlying causes. A difference in balance between causes in the two types of patients is more than likely.2 For example, arrhythmias can only develop by the combination of a trigger and a substrate. In outpatient clinic patients with AAF, there might be a larger role for the substrate, while in critically ill patients with AAF the trigger is of utmost importance. In critically ill patients, the underlying trigger should be treated first. Treatment of the underlying disease, pain and anxiety relief, oxygenation, and correction of hemodynamics are mandatory, and this essential therapy leads to conversion to sinus rhythm in the majority of cases without further intervention. Direct current cardioversion, based on our experience and supported by the literature,3 has no sustainable result if the underlying triggers are not eliminated. Direct current cardioversion therefore, should only be used in really desperate situations, although, as mentioned before, the efficacy remains debatable.