Congenital anomaly: heart with three atria
Either LA or RA can be divided into 2 compartments<unk>  sinistrum or<unk>  dextrum)
Can be associated with other congenital syndromes including tetralogy of Fallot, double outlet RV, coarctation of the aorta, VSD, AV septal defect
0.1-0.4% incidence in USA
Cor triatriatum
Pericarditis
Stone heart
Pulmonary Hypertension
Hypertrophic cardiomyopathy
Right heart failure
Atrio-esophageal fistula
Atrial Myxoma