HCM: hypertrophic cardiomyopathy; ICD: implantable cardioverter-defibrillator; LV: left ventricular; NSVT: nonsustained ventricular tachycardia; SCD: sudden cardiac death; VF: ventricular fibrillation; VT: ventricular tachycardia.
* The strength of association between these factors and SCD or VT/VF varies, but the presence of a single factor confers a high risk status. Refer to topics on ventricular arrhythmias in HCM for more details.
¶ A positive family history requires a sudden death event in a first-degree or close relative ≤50 years of age that was likely caused by HCM.