Utility of Real-Time 3-Dimensional Echocardiography and Magnetic Resonance Imaging for Evaluation of Danon Disease

A 21-year-old man was admitted to the hospital with exertional dyspnea. At the age of 14, he was diagnosed with Danon disease by genetic analysis (a 2–base-pair deletion at positions 288 and 289 in exon 3 was identified in the lysosome-associated membrane protein-2 [LAMP2] gene of the patient, which led to a frameshift and resulted in a premature stop codon). A chest radiograph demonstrated moderate cardiomegaly (cardiothoracic ratio of 58%). The ECG exhibited normal sinus rhythm, wide and bifid P waves with a duration of 170 ms, complete left bundle-branch block with a QRS duration of 200 ms, and a leftward axis (−2°; Figure 1). Figure 1. Twelve-lead ECGs. Echocardiography revealed left ventricular (LV) dilatation with an end-diastolic internal dimension of 60 mm and diffusely hypokinetic LV wall motion with fractional shortening of 8% (Figure 2; Movie I of the online-only Data Supplement). …