Incidental Finding of Cor Triatriatum Sinister in an Asymptomatic Woman With Ankylosing Spondylitis.

We present a 24-year-old woman with symptoms of backache, acute peripheral arthritis, joint swelling, and erythema, diagnosed with ankylosing spondylitis (AS) and determined to have cor triatriatum sinister (CTS) without cardiac symptoms. On physical examination, the patient had a rythmic S1 with a loud pulmonic component to her S2 and a grade 2/6 systolic murmur along the left sternal edge. Pulmonary examination was normal.