Table 4.

Major cardiac events in the overall cohort

Age at diagnosis (years)	Age at MaCE (years)	Genetic test results (P/LP variant)	Major cardiac event	Cause of death/indication for ICD
0 (foetal)	0.4	None	Death (cardiac)	Advanced heart failure
0 (foetal)	0.5	MYBPC3 (homozygous)	Death (cardiac)	Advanced heart failure awaiting transplant
0 (foetal)	12.2	MYH7	ICD—primary prevention	Family history of SCD, severe septal hypertrophy, LGE on CMR
1.1	4.1	MYBPC3	Surgical myectomy	Symptomatic with LVOT gradient >100 mmHg
2.7	13.7	MYH7	Aborted SCD; ICD—secondary prevention	Secondary prevention
4.2	8.7	MYH7	ICD—primary prevention	Family history of SCD, extreme septal hypertrophy, and abnormal BP response
4.4	8.5	MYBPC3 (compound heterozygote)	ICD—primary prevention	Family history of SCD, abnormal BP response (two appropriate shocks)
5.4	6.5	MYBPC3	Surgical myectomy	Symptomatic with severe LVOTO on optimal medical therapy
7	10.9	MYBPC3 (compound heterozygote)	Death (SCD)	SCD
7.6	15.6	MYH7	ICD—primary prevention	Family h/o SCD, severe septal hypertrophy, and palpitations
8.8	10	MYH7	ICD—primary prevention	Extreme septal hypertrophy, abnormal BP response
8.8	14.3	None	Aborted SCD; ICD—secondary prevention	Secondary prevention
9.1	9.1	None	Surgical myectomy (+ primary prevention ICD 3 years later)	Family history of SCD, severe LVOTO, and NSVT
11.5	14.3	MYH7	Surgical myectomy	Symptomatic with severe LVOTO on optimal medical therapy
13	13.2	MYBPC3 (compound heterozygote)	ICD—primary prevention	Severe septal hypertrophy, NSVT, and abnormal BP response (one appropriate shock)
14.5	14.6	None	Surgical myectomy (+ primary prevention ICD)	Severe LVOTO, NSVT, and abnormal BP response on exercise
15.9	16.5	TNNT2	ICD—primary prevention	Unexplained syncope, severe septal hypertrophy, and abnormal ECG on exercise

CMR, cardiac magnetic resonance; LGE, late gadolinium enhancement; LVOTO, LV outflow tract obstruction; MaCE, major cardiac event; NSVT, non-sustained ventricular tachycardia; P/LP, pathogenic or likely pathogenic.