Rintaro Hojo et al. JACEP 2017;j.jacep.2016.12.008 Distribution of Nonpulmonary Vein Foci in the Atria (A) In the first PV isolation session, firings in the superior vena cava (SVC) were dominant. (B) In the second PV isolation session, the number and prevalence of foci had increased significantly. AP = anteroposterior; CS = coronary sinus; IAS = interatrial septum; LA = left atrium; MA = Marshall vein area; PA = posteroanterior; RA = right atrium; TA = tricuspid annulus area; other abbreviation as in Figure 1. Rintaro Hojo et al. JACEP 2017;j.jacep.2016.12.008 American College of Cardiology Foundation