Atrial fibrillation (AF) is the most common arrhythmia with a prevalence of 1-2% in Canada.​1​ On an ECG, AF is recognized by an irregularly irregular rhythm lacking p waves (Figure 1). In addition to the clinical and pathophysiological pattern, AF can be categorized as “valvular AF” (VAF) or “nonvalvular AF” (NVAF). While there are varying definitions for VAF, it is usually restricted to AF in the presence of a mechanical heart valve, moderate …