There is increasing evidence supporting the association of late gadolinium enhancement on cardiac MRI with the risk of sudden death and it is included as a risk modifier.S7.4-37 S7.4-39 LV aneurysm may be Table 8. Major Clinical Features Associated With Increased Risk of SCD in Patients With HCM Established risk factors* Survival from a cardiac arrest due to VT or VF S7.4-1,S7.4 5,S7.4 6 Spontaneous sustained VT causing syncope or hemodynamic Family history of SCD associated with HCM S7.4 25,S7.4 26 LV wall thickness 30 mm S7.4-2,S7.4-3,S7.4 23,S7.4 24 Unexplained syncope within 6 mo S7.4 8,S7.4 26 Abnormal blood pressure response during exercise S7.4 5,S7.4 28,S7.4 29 Potential risk modifiers Delayed hyperenhancement on cardiac MRI S7.4 37 S7.4 39,S7.4 54 LVOT obstruction S7.4-2,S7.4-4 Syncope >5 y ago S7.4 8,S7.4 26 High-risk subsets LV aneurysm S7.4 40,S7.4 55,S7.4 56 *There is general agreement in the literature that these factors independently convey an increased risk for SCD in patients with HCM. Decrease in blood pressure of 20 mmHg or failure to increase systolic blood pressure >20 mmHg during exertion. There is a lack of agreement in the literature that these modifiers independently convey an increased risk of SCD in patients with HCM; however, a risk modifier when combined with a risk factor often identifies a patient with HCM at increased risk for SCD beyond the risk conveyed by the risk factor alone. A small subset of patients with an LVEF <50% (end-stage disease) or an LV aneurysm warrant consideration for ICD implantation.S7.4-52 HCM indicates hypertrophic cardiomyopathy; ICD, implantable cardioverter- defibrillator; LV, left ventricular; LVEF, left ventricular ejection fraction; LVOT, left ventricular outflow tract; NSVT, nonsustained ventricular tachycardia; SCD, sudden cardiac death; VT, ventricular tachycardia; and VF, ventricular fibrillation. 