AF Burden
Currently, AF is classified as paroxysmal, persistent or permanent, but treatment generally relies on a binary classification (i.e., presence or absence of AF to determine the decision for anticoagulation).69 A quantitative approach to define the burden of AF has been suggested. This factors in the number of episodes or the proportion of time a patient spends in AF during a particular monitoring period.70 AF burden has been noted to have a predictive value for AF-related strokes and thus, could guide management.70,71 However, even with wearable and implantable technologies allowing longer monitoring durations, burden of AF is difficult to determine. Also, the minimum AF duration required for anticoagulation is not well defined.72
Another scenario in which AF burden becomes important is SCAF. Higher AF burden along with the traditional risk factors (CHA2DS2-VASc score) are more likely to benefit from oral anticoagulants than low to medium burden of AF and without risk factors.73 A general rule of thumb for anticoagulation, regardless of indication, is the need to maintain efficacy while minimizing the bleeding risk.74However, the exact cut-offs are not well defined and leads to considerable variation in management depending on the provider.75 With advancements in wearable and intracardiac monitoring techniques as well as their wider availability,76 detection of SCAF is also increasing and the knowledge gaps need to be addressed more clearly. Two highly anticipated trials Apixaban for the Reduction of Thrombo-Embolism in Patients With Device-Detected Sub-Clinical Atrial Fibrillation77 and Non-vitamin K Antagonist Oral Anticoagulants in Patients With Atrial High Rate Episodes78 will likely help inform management in these patients.
A preliminary study using DNN model has been able to assess AF burden from 24-hour Holter monitor data.79 Although this proves feasibility of developing the prototype, translation of such models into clinical use would require validation and clearer guidelines as to the importance of AF burden and duration for guiding anticoagulation therapy.