Table 1.

Known risk factors for SCD in HCM patients.¹⁴

Risk factor	Definition
1. Positive family history for premature sudden cardiac death	Unexpected nontraumatic death within one hour after the onset of symptoms and without previous severe symptoms <55 years, including unwitnessed unexpected nocturnal death in a relative. Including equivalents as successful reanimation or appropriate ICD discharge.
2. Prior cardiac arrest or sustained ventricular tachycardia	Cardiac arrest (VF) in history or spontaneously occurring sustained ventricular tachycardia.
3. Nonsustained ventricular tachycardia	One or more runs of ≥3 consecutive ventricular extrasystoles at a rate of more than 120 beats/min lasting for <30 seconds.
4. Extreme left ventricular hypertrophy	Maximum left ventricular wall thickness of ≥30 mm.
5. Abnormal blood pressure response during upright exercise	A failure of the systolic blood pressure to rise by >20 mmHg from baseline values, or a fall of >10 mmHg from the maxi-mum blood pressure during upright exercise.
6. Unexplained syncope	≥2 episodes of unexplained syncope in the previous year.