A 30-year-old man presented for evaluation of palpitations and exertional dyspnea when climbing stairs, mostly at night. Physical examination was unremarkable, except for sinus tachycardia. Laboratory test results were all within normal limits. The electrocardiogram showed sinus rhythm and early repolarization changes (Figure, A). Thirty-day event monitoring showed sinus tachycardia during episodes of palpitation. The transthoracic echocardiogram is shown in Figure, B, and Video 1. The left ventricular ejection fraction was between 56% and 60%. The estimated pulmonary artery systolic pressure was 24 mm Hg. A transesophageal echocardiogram was also performed (Video 2 and Video 3).