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Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 September 25, 2018 e315 CLINICAL STATEMENTS AND GUIDELINES

7.4 Hypertrophic Cardiomyopathy

Recommendations for HCM References that support the recommendations are summarized in Online Data Supplement 31.

COR LOE Recommendations

I B-NR 1. In patients with HCM, SCD risk stratification should be performed at the time of initial evaluation and periodically thereafter.S7.4-1–S7.4-8

I B-NR 2. In patients with HCM who have survived an SCA due to VT or VF, or have spontaneous sustained VT causing syncope or hemodynamic compromise, an ICD is recommended if meaningful survival greater than 1 year is expected.S7.4-1,S7.4-6,S7.4-9,S7.4-10

I B-NR 3. In first-degree relatives of patients with HCM, an ECG and echocardiogram should be performed.S7.4-11–S7.4-17

I B-NR 4. In first-degree relatives of patients with HCM due to a known causative mutation, genetic counseling and mutation-specific genetic testing are recommended.S7.4-13–S7.4-15,S7.4-18,S7.4-19

IIa B-NR 5. In patients with clinically suspected or diagnosed HCM, genetic counseling and genetic testing are reasonable.S7.4-13–S7.4-15,S7.4-18–S7.4-22

IIa B-NR 6. In patients with HCM and 1 or more of the following risk factors, an ICD is reasonable if meaningful survival of greater than 1 year is expected: a. Maximum LV wall thickness ≥30 mm

(LOE: B-NR).S7.4-2,S7.4-3,S7.4-23,S7.4-24 b. SCD in 1 or more first-degree relatives

presumably caused by HCM (LOE: C-LD).S7.4-25,S7.4-26 c. 1 or more episodes of unexplained

syncope within the preceding 6 months (LOE: C-LD).S7.4-8,S7.4-26

C-LD

C-LD

IIa B-NR

7. In patients with HCM who have spontaneous NSVT (LOE: C-LD) S7.4-2,S7.4-26,S7.4-27 or an abnormal blood pressure response with exercise (LOE: B-NR) S7.4-5,S7.4-28,S7.4-29, who also have additional SCD risk modifiers or high-risk features, an ICD is reasonable if meaningful survival greater than 1 year is expected. C-LD

IIb B-NR

8. In patients with HCM who have NSVT (LOE: B-NR)S7.4-2,S7.4-26,S7.4-27 or an abnormal blood pressure response with exercise (LOE: B-NR)S7.4-5,S7.4-28,S7.4-29 but do not have any other SCD risk modifiers, an ICD may be considered, but its benefit is uncertain. B-NR

IIb C-LD 9. In patients with HCM and a history of sustained VT or VF, amiodarone may be considered when an ICD is not feasible or not preferred by the patient.S7.4-30,S7.4-31

III: No Benefit B-NR 10. In patients with HCM, an invasive electrophysiological study with programmed ventricular stimulation should not be performed for risk stratification.S7.4-32,S7.4-33

III: No Benefit B-NR 11. In patients with an identified HCM genotype in the absence of SCD risk factors, an ICD should not be implanted.S7.4-7,S7.4-34,S7.4-35 Refer to the ACCF/AHA HCM guideline for the definition of HCM.S7.4-36

Recommendation-Specific Supportive Text

1.	 Patients with HCM have approximately a 1% risk of SCD per year.S7.4-1,S7.4-6 Selection of patients who are appropriate candidates for implantation of an ICD can be a difficult clinical decision because of the individuality of each patient and family, variable definitions of risk factors and risk modifiers, sparse clinical data, the relative infrequency of both HCM and  SCD in most clinical practices, and the potential complications of living with an ICD. Table 8 lists risk factors and risk modifiers associated with SCD in patients with HCM. ICD risk stratification should be performed every 1 to 3 years in patients with HCM. 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

compromise S7.4-1,S7.4–5,S7.4–6 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 NSVT ≥3 beats S7.4-2,S7.4–26,S7.4–27 Abnormal blood pressure response during exercise† S7.4–5,S7.4–28,S7.4–29 Potential risk modifiers‡ <30 y S7.4–5,S7.4–26 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 LVEF <50% S7.4–52 *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 mm Hg or failure to increase systolic blood pressure >20 mm Hg 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 cardioverterdefibrillator; 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.

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