Cardiomyopathy 2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Edzel Lorraine Co, DMD, MD[2]

2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy

Recommendation for Shared Decision-Making

Class I	Level of Evidence
1. For patients with HCM or at risk for HCM, shared decision-making is recommended in developing a plan of care (including but not limited to decisions regarding genetic evaluation, activity, lifestyle, and therapy choices) that includes a full disclosure of the risks, benefits, and anticipated outcomes of all options, as well the opportunity for the patient to express their goals and concerns.	B-NR

Recommendation for Multidisciplinary HCM Centers

Class I	Level of Evidence
1. In patients with HCM in whom septal reduction therapy (SRT) is indicated, the procedure should be performed at experienced centers (comprehensive or primary HCM centers) with demonstrated excellence in clinical outcomes for these procedures.	C-LD
Class IIa	Level of Evidence
2. In patients with HCM, consultation with or referral to a comprehensive or primary HCM center is reasonable to aid in complex disease-related management decisions.	C-LD

Recommendation for Diagnosis, Initial Evaluation, and Follow-up

Class I	Level of Evidence
1. In patients with suspected HCM, comprehensive physical examination and complete medical and 3-generation family history is recommended as part of the initial diagnostic assessment.	B-NR

Recommendation for Echocardiography

Class I	Level of Evidence
1. In patients with suspected HCM, a trans-thoracic echocardiogram (TTE) is recommended in the initial evaluations.	B-NR
Class I	Level of Evidence
2. In patients with HCM with no change in clinical status or events, repeat TTE is recommended every 1 to 2 years to assess the degree of myocardial hypertrophy, dynamic left ventricular outflow tract obstruction (LVOTO), mitral regurgitation, and myocardial function.	B-NR children
	C-LD adult
Class I	Level of Evidence
3. For patients with HCM who experience a change in clinical status or a new clinical event, repeat TTE is recommended.	B-NR
Class I	Level of Evidence
4. For patients with HCM and resting left ventricular outflow tract gradient <50 mm Hg, a TTE with provocative maneuvers is recommended.	B-NR
Class I	Level of Evidence
6. For symptomatic patients with HCM who do not have a resting or provocable outflow tract gradient ≥50 mm Hg on TTE, exercise TTE is recommended for the detection and quantification of dynamic LVOTO.	B-NR
Class I	Level of Evidence
7. For patients with HCM undergoing surgical septal myectomy, intraoperative transesophageal echocardiogram (TEE) is recommended to assess mitral valve anatomy and function and adequacy of septal myectomy.	B-NR
Class I	Level of Evidence
8. For patients with HCM undergoing alcohol septal ablation, TTE or intraoperative TEE with intracoronary ultrasound-enhancing contrast injection of the candidate’s septal perforator(s) is recommended.	B-NR
Class I	Level of Evidence
9. Screening: In first-degree relatives of patients with HCM, a TTE is recommended as part of initial family screening and periodic follow-up.	B-NR
Class I	Level of Evidence
10. Screening: In individuals who are genotype-positive or phenotype-negative, serial echocardiography is recommended at periodic intervals depending on age (1 to 2 years in children and adolescents, 3 to 5 years in adults) and change in clinical status.	B-NR
Class IIa	Level of Evidence
11. For patients with HCM, TEE can be useful if TTE is inconclusive in clinical decision-making regarding medical therapy, and in situations such as planning for myectomy, exclusion of subaortic membrane or mitral regurgitation secondary to structural abnormalities of the mitral valve apparatus, or in the assessment of the feasibility of alcohol septal ablation.	C-LD
Class IIa	Level of Evidence
12. For patients with HCM in whom the diagnoses of apical HCM, apical aneurysm, or atypical patterns of hypertrophy is inconclusive on TTE, the use of an intravenous ultrasound-enhancing agent is reasonable particularly if other imaging modalities such as cardiovascular magnetic resonance (CMR) are not readily available or contraindicated.	B-NR
Class IIa	Level of Evidence
13. For asymptomatic patients with HCM who do not have a resting or provocable outflow tract gradient ≥50 mm Hg on standard TTE, exercise TTE is reasonable for the detection and quantification of dynamic LVOTO.	C-LD

Recommendation for Cardiovascular Magnetic Resonance Imaging

Class I	Level of Evidence
1. For patients suspected to have HCM in whom echocardiography is inconclusive, CMR imaging is indicated for diagnostic clarification.	B-NR
Class I	Level of Evidence
2. For patients with left ventricular hypertrophy in whom there is a suspicion of alternative diagnoses including infiltrative or storage disease as well as athlete’s heart, CMR imaging is useful.	B-NR
Class I	Level of Evidence
3. For patients with HCM who are not otherwise identified as high risk for sudden cardiac death (SCD), or in whom a decision to proceed with implantable cardioverter defibrillator (ICD) remains uncertain after clinical assessment that includes personal/family history, echocardiography, and ambulatory electrocardiographic monitoring, CMR imaging is beneficial to assess for maximum left ventricular (LV) wall thickness, ejection fraction (EF), LV apical aneurysm, and extent of myocardial fibrosis with late gadolinium enhancement.	B-NR
Class I	Level of Evidence
4. For patients with obstructive HCM in whom the anatomic mechanism of obstruction is inconclusive on echocardiography, CMR imaging is indicated to inform the selection and planning of SRT.	B-NR
Class IIb	Level of Evidence
5. For patients with HCM, repeat contrast-enhanced CMR imaging on a periodic basis (every 3 to 5 years) for the purpose of SCD risk stratification may be considered to evaluate changes in late gadolinium enhancement and other morphologic changes, including EF, development of apical aneurysm, or LV wall thickness.	C-EO

Recommendation for Heart Rhythm Assessment

Class I	Level of Evidence
1. In patients with HCM, a 12-lead ECG is recommended in the initial evaluation and as part of periodic follow-up (every 1 to 2 years)	B-NR
Class I	Level of Evidence
2. In patients with HCM, 24- to 48-hour ambulatory electrocardiographic monitoring is recommended in the initial evaluation and as part of periodic follow-up (every 1 to 2 years) to identify patients who are at risk for SCD and guide management of arrhythmias.	B-NR
Class I	Level of Evidence
3. In patients with HCM who develop palpitations or lightheadedness, extended (>24 hours) electrocardiographic monitoring or event recording is recommended, which should not be considered diagnostic unless patients have had symptoms while being monitored.	B-NR
Class I	Level of Evidence
4. In first-degree relatives of patients with HCM, a 12-lead ECG is recommended as a component of the screening algorithm.	B-NR
Class IIa	Level of Evidence
5. In patients with HCM who have additional risk factors for atrial fibrillation (AF), such as left atrial dilatation, advanced age, and New York Heart Association (NYHA) class III to class IV heart failure (HF), and who are eligible for anticoagulation, extended ambulatory monitoring is reasonable to screen for AF as part of initial evaluation and periodic follow-up (every 1 to 2 years)	B-NR
Class IIb	Level of Evidence
5. In adult patients with HCM without risk factors for AF and who are eligible for anticoagulation, extended ambulatory monitoring may be considered to assess for asymptomatic paroxysmal AF as part of initial evaluation and periodic follow-up (every 1 to 2 years).	B-NR

Recommendation for Angiography and Invasive Hemodynamic Assessment

Class I	Level of Evidence
1. For patients with HCM who are candidates for SRT and for whom there is uncertainty regarding the presence or severity of LVOTO on noninvasive imaging studies, invasive hemodynamic assessment with cardiac catheterization is recommended.	B-NR
Class I	Level of Evidence
2. In patients with HCM with symptoms or evidence of myocardial ischemia, coronary angiography (CT or invasive) is recommended.	B-NR
Class I	Level of Evidence
3. In patients with HCM who are at risk of coronary atherosclerosis, coronary angiography (CT or invasive) is recommended before surgical myectomy.	B-NR

Recommendation for Exercise Stress Testing

Class I	Level of Evidence
1. For symptomatic patients with HCM who do not have resting or provocable outflow tract gradient ≥50 mm Hg on TTE, exercise TTE is recommended for the detection and quantification of dynamic LVOTO.	B-NR
Class I	Level of Evidence
2. In patients with HCM with symptoms or evidence of myocardial ischemia, coronary angiography (CT or invasive) is recommended.	B-NR
Class IIa	Level of Evidence
3. In patients with HCM, exercise stress testing is reasonable to determine functional capacity and to provide prognostic information as part of initial evaluation.	B-NR
Class IIa	Level of Evidence
4. For asymptomatic patients with HCM who do not have a resting or provocable outflow tract gradient ≥50 mm Hg on standard TTE, exercise TTE is reasonable for the detection and quantification of dynamic LVOTO.	C-LD
Class IIb	Level of Evidence
5. In patients with obstructive HCM, who are being considered for SRT, and in whom functional capacity or symptom status is uncertain, exercise stress testing may be reasonable.	C-EO
Class IIb	Level of Evidence
6. In patients with HCM in whom functional capacity or symptom status is uncertain, exercise stress testing may be considered every 2 to 3 years.	C-EO

Recommendation for Genetics and Family Testing

Class I	Level of Evidence
1. In patients with HCM, evaluation of familial inheritance, including a 3-generation family history, is recommended as part of the initial assessment.	B-NR
Class I	Level of Evidence
2. In patients with HCM, genetic testing is beneficial to elucidate the genetic basis to facilitate the identification of family members at risk for developing HCM (cascade testing).	B-NR
Class I	Level of Evidence
3. In patients with an atypical clinical presentation of HCM or when another genetic condition is suspected to be the cause, a work-up including genetic testing for HCM and other genetic causes of unexplained cardiac hypertrophy (“HCM phenocopies”) is recommended.	B-NR
Class I	Level of Evidence
4. In patients with HCM who choose to undergo genetic testing, pre- and posttest genetic counseling by an expert in the genetics of cardiovascular disease is recommended so that risks, benefits, results, and their clinical significance can be reviewed and discussed with the patient in a shared decision-making process.	B-NR
Class I	Level of Evidence
5. When performing genetic testing in an HCM proband, the initial tier of genes tested should include genes with strong evidence to be disease-causing in HCM.	B-NR
Class I	Level of Evidence
6. In first-degree relatives of patients with HCM, both clinical screening (ECG and 2D echocardiogram) and cascade genetic testing (when a pathogenic/likely pathogenic variant has been identified in the proband) should be offered.	B-NR
Class I	Level of Evidence
7. In families where a sudden unexplained death has occurred with a postmortem diagnosis of HCM, postmortem genetic testing is beneficial to facilitate cascade genetic testing and clinical screening in first-degree relatives.	B-NR
Class I	Level of Evidence
8. In patients with HCM who have undergone genetic testing, serial reevaluation of the variant(s) identified is recommended to assess for variant reclassification, which may impact diagnosis and cascade genetic testing in family members.	B-NR
Class I	Level of Evidence
9. In affected families with HCM, preconception and prenatal reproductive and genetic counseling should be offered.	B-NR
Class IIb	Level of Evidence
10. In patients with HCM, the usefulness of genetic testing in the assessment of risk of SCD is uncertain.	B-NR
Class IIb	Level of Evidence
11. In patients with HCM who harbor a variant of uncertain significance, the usefulness of clinical genetic testing of phenotype-negative relatives for the purpose of variant reclassification is uncertain.	B-NR
Class III: No Benefit	Level of Evidence
12. For patients with HCM who have undergone genetic testing and were found to have no pathogenic variants (ie, harbor only benign/likely benign variants), cascade genetic testing of the family is not useful.	B-NR
Class III: No Benefit	Level of Evidence
13. Ongoing clinical screening is not indicated in genotype-negative relatives in families with genotype-positive HCM, unless the disease-causing variant is downgraded to variant of uncertain significance, likely benign, or benign variant during follow-up.	B-NR

Recommendations for Individuals Who Are Genotype-Positive, Phenotype-Negative

Class I	Level of Evidence
1. In individuals who are genotype-positive, phenotype-negative for HCM, serial clinical assessment, electrocardiography, and cardiac imaging are recommended at periodic intervals depending on age (every 1 to 2 years in children and adolescents, and every 3 to 5 years in adults) and change in clinical status.	B-NR
Class IIa	Level of Evidence
2. In individuals who are genotype-positive, phenotype-negative for HCM, participation in competitive athletics of any intensity is reasonable.	C-LD
Class III: No Benefit	Level of Evidence
3. n individuals who are genotype-positive, phenotype-negative for HCM, ICD is not recom-mended for primary prevention	B-NR