Table 3.

Clinical phenotype and outcomes of patients with atrial and ventricular arrhythmias

Age at diagnosis of HCM	Arrhythmia	Age at first arrhythmia	Cardiac phenotype at presentation	Clinical information	Outcome
9	SVT and AF	14	Concentric LVH. No LVOTO. No systolic impairment.	Palpitations with SVT on ambulatory ECG. Treated with bisoprolol and diltiazem. At age 18 AF requiring DC cardioversion and therapy change (amiodarone).	Alive.
15	AF	18	Concentric LVH. No LVOTO. MWT 10 mm.	Fast AF with decompensated heart failure. Treated with diuretics, amiodarone and digoxin increased. At age 19 fast AF requiring DC cardioversion.	Died secondary to heart failure at age 19.
10	AET	11	Concentric LVH. No LVOTO.	Palpitations with AET on ambulatory ECG. Treated with verapamil.	Alive.
10	SVT	13	Concentric LVH. No systolic impairment.	Asymptomatic. Ambulatory monitoring showed SVT. Treated with B-blockers.	Alive.
7	Atrial flutter	28	Concentric LVH. MWT 14 mm.	Unknown clinical presentation.	Transitioned to adult care.
10	AF	19	Concentric LVH. MWT 12. No LVOTO. No systolic impairment.	Presented with chest pain and palpitations.	Transitioned to adult care.
11	Atrial flutter	13	Echo showed reduced EF and FS. Concentric LVH. No LVOTO. MWT 11 mm.	Palpitations with atrial flutter in the context of viral illness. Treated with digoxin and DC cardioversion. Maintenance therapy of flecainide, lisinopril and aspirin.	Transitioned to adult care.
10	AF with fast ventricular conduction	17	Mild concentric LVH. No LVOTO. MWT 13 mm.	Fast AF postoperatively with lactic acidosis.	Died secondary to decompensated heart failure at age 17.
5	NSVT	14	Presented at age 5 with symptoms suggestive of dilated cardiomyopathy, listed for transplant. Concentric LVH. MWT 12 mm. Systolic impairment. No LVOTO.	Asymptomatic. Treated with amiodarone.	Alive.
14	NSVT	16	Concentric LVH. MWT 11 mm. No LVOTO. No systolic impairment.	Detected during episode of pancreatitis.	Alive.
11	NSVT	12	Concentric LVH. No systolic impairment. No LVOTO. MWT 15 mm.	Palpitations with NSVT on ambulatory ECG. Treated with amiodarone.	Died at age 32, unknown cause.
9	NSVT	17	Concentric LVH. MWT 15 mm.	Asymptomatic. Treated with nifedipine.	Alive.

AET, atrial ectopic tachycardia; AF, atrial fibrillation; DC, direct current; EF, ejection fraction; FS, fractional shortening; HCM, hypertrophic cardiomyopathy; LVH, left ventricular hypertrophy; LVOTO, left ventricular outflow tract obstruction; MWT, maximal wall thickness; NSVT, non-sustained ventricular tachycardia; SVT, supraventricular tachycardia.