Cumulative Burden of Atrial Fibrillation: An Application Using a Nonlinear Mixed Effects Model (303247)

Keywords: nonlinear mixed effects model, PROC NLMIXED, cumulative burden

Arrhythmias are disorders of the regular rhythmic beating of the heart. Atrial Fibrillation (AF) is one type of rhythmic problem. In the condition of atrial fibrillation, many parts of the atria start emitting uncoordinated electrical signals. The atria pumps too fast and unevenly and won't fully contract. An estimated 2.5 million Americans are living with atrial fibrillation and estimated to be as many as 12 million people will have the condition by 2050. The most common practice of monitoring AF is done using electrocardiogram which captures arrhythmia at that specific time, a snapshot of the state of AF (a binary response). Recently, there has been an increase in the usage devices that monitor the AF episodes continuously and record the duration of each AF episodes. We introduce a nonlinear mixed-effects model to fit the cumulative burden (duration) of AF and identify factors that modulate the shape and the scale of the cumulative burden curve of AF. Application of this model is illustrated using data from 51 patients who underwent catheter ablation for AF at Cleveland Clinic and enrolled in a continuous monitoring of AF using Reveal continuous monitor (Metronic Inc., Minnesota).