PMC

(a) Patient’s ECG is displayed at age eight, showing normal sinus rhythm, LV hypertrophy, and T wave inversion in leads I, II, AVL, V3-V6. (b) Patient’s ECG is displayed at age 10, seventeen months post-AICD implantation, showing atrial tachycardia at 125 beats per minute. (c) Patient’s ECG is displayed at age 14, showing dual-paced, dual-sensed, dual-inhibited (DDD) pattern, left axis deviation, right ventricular hypertrophy, and prominent T wave inversion in leads V4-V6.

Echocardiographic variables are tracked over age. (a) Patient’s diastolic LV interior dimensions increased over time (moderate to strong correlation; R = 0.5576). (b) LV shortening fraction decreased considerably over time, reaching a minimum of 25% (strong correlation; R = −0.8439). (c) and (d) Diastolic LV wall thickness and diastolic septal wall thickness increased over time (both strong correlation; R = 0.8509 and R = 0.8417, respectively), consistent with worsening HCM. (e) Peak and Mean LVOT gradient decreased over time (both strong correction; R = −0.8920 and −0.7431, respectively), indicating successful treatment with dual-chamber pacing. (f) Aortic root diameter increased over time (strong correlation; R = 0.8150).

An algorithm is presented for managing cardiac symptoms in Danon disease.
*Risk factors from 2011 ACCF/AHA Guidelines for Diagnosis and Treatment of HCM:
history of ventricular fibrillation, sustained ventricular tachycardia, or sudden cardiac arrest (very strong risk factor)
family history of SCD (strong risk factor)episodes of unexplained syncope (strong risk factor)
Maximal ventricular wall thickness ≥30 mm (strong risk factor)
Episodes of NSVT on Holter monitoring (medium risk factor)
Failure of a systolic blood pressure response (medium risk factor)
**Risk modifiers include LVOT gradient ≥30 mm Hg, LGE on cMRI, LV apical aneurysm, and known genetic mutation.
^aSCD-HeFT trial: Single-lead, shock-only ICD therapy is recommended for patients who classify under NYHA class II or III and have a LVEF of 35% or less.