“…The absence of P waves is the most significant marker of AF; however, since locating the P wave fiducial point is often difficult when extensive noise is present, the results relied on this hallmark are moderate to high (73.0% to 91.0%, 71.0% to 80.0%, respectively) (Fukunami et al, 1991;Opolski et al, 1997;Budeus et al, 2003). The methods based on RR intervals are, therefore, preferable, with a higher sensitivity and specificity compared to the former method (93.7% vs. 80.7%, 93.0% vs. 75.7% on average, respectively) (Moody and Mark, 1983;Tateno and Glass, 2001;Duverney et al, 2002;Dash et al, 2009). However, it is important to note that regular RR intervals occur in the presence of an atrioventricular (AV) block or ventricular or AV junctional tachycardia when AF is present (Levy et al, 1998).…”