New onset atrial fibrillation in the ICU: An unexplored future of anticoagulation.

In the letter to the editor, “New-onset AF in theMedical Intensive Care Unit: Catch me if you can,” Vadakken et al. raised very interesting postulations regarding duration of atrial fibrillation (AF) and associated patient outcomes. The data regarding new-onset AF in the setting of acute illness warranting admission to the medical intensive care unit is limited,1,2,3 with few validated tools for risk stratification and optimal management for these patients. One limitation of our study is an unclear total duration of AF (as well as the duration of the longest AF episode) during the admission as a consequence of our retrospective study design. The group from McMaster University presented data estimating the incidence of newonset AF lasting at least 30 s in critically ill patients at 18.9% (95% CI 14.2%−24.3%) using 14-day continuous ECGmonitors. Using continuous monitoring is a more rigorous way to surveil for episodes of newonset AF. The AF Occurring Transiently with Stress (AFOTS) follow-up study, cited by Vadakken et al.,4 will utilize serial ambulatory monitoring and therefore promises to offer valuable insight as to what happens to these types of patients after they are discharged from the hospital. As the letter by Vadakken et al. notes, the clinical team only recognized 70% of episodes of AF that were detected by the 14-day inhospital ECG patch monitor. It is well documented that AF is associated with increased risk of intracardiac thrombosis and stroke.5 This highlights the concern that we may be missing clinically significant AF and along with it, the opportunity to prevent strokes. While rigorous monitoring can help catch more episodes of new-onset AF, this raises the question of what to do with the data (e.g., what degree of AF burden is associated with ischemic stroke).6 Another related area of assessment may be to assess the relationship between CHARGE-AF and new-onset AF as compared to CHA2DS2-VASc for predictors of recurrent AF after discharge, as our study showed a closer risk prediction by the former tool as compared to the latter. Again, we are excited about the AFOTS study and eagerly await its results.4 We hope that it will shed light on factors that influence recurrent AF after discharge and help to quantify the associated stroke risk. We always welcome continued interest and insight from other research groups. Thank you for your interest in our work. Respectfully, Edan Zitelny, MD and the “New-onset atrial fibrillation incidence and associated outcomes in the medical intensive care unit” Research Team