Diagnosis
4. Shared Decision-Making
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 and caregivers to express their goals and concerns. ( 1, B-NR )
5. Multidisciplinary HCM Centers
1. In patients with HCM in whom 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 (Table 3, Table 4). ( 1, C-LD )
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 (Table 3). ( 2a, C-LD )
Treatment
6. Diagnosis, Initial Evaluation, and Follow-Up
6.1. Clinical Diagnosis
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 (Table 5, Table 6). ( 1, B-NR )
6.2. Echocardiography
1. In patients with suspected HCM, a transthoracic echocardiogram (TTE) is recommended in the initial evaluation. ( 1, B-NR )
2. 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 (MR), and myocardial function (Figure 1)
In pediatric patients with HCM who have no change in clinical status or events. ( 1, B-NR )
In adult patients with HCM who have no change in clinical status or events. ( 1, C-LD )
3. For patients with HCM who experience a change in clinical status or a new clinical event, repeat TTE is recommended. ( 1, B-NR )
4. For patients with HCM and resting peak LVOT gradient <50 mm Hg, a TTE with provocative maneuvers is recommended. ( 1, B-NR )
5. For symptomatic patients with HCM who do not have a resting or provocable outflow tract peak gradient ≥50 mm Hg on TTE, exercise TTE is recommended for the detection and quantification of dynamic LVOTO. ( 1, B-NR )
6. For patients with HCM who are undergoing surgical septal myectomy, intraoperative transesophageal echocardiogram (TEE) is recommended to assess mitral valve anatomy and function and adequacy of septal myectomy. ( 1, B-NR )
7. For patients with HCM who are undergoing alcohol septal ablation, TTE or intraoperative TEE with intracoronary ultrasound-enhancing contrast injection of the candidate’s septal perforator(s) is recommended. ( 1, B-NR )
8. For patients with HCM who have undergone SRT, TTE within 3 to 6 months after the procedure is recommended to evaluate the procedural results. ( 1, B-NR )
9. Screening: In first-degree relatives of patients with HCM, a TTE is recommended as part of initial family screening and periodic follow- up (Figure 1, Table 6). ( 1, B-NR )
10. Screening: In individuals who are genotype-positive, phenotype-negative, 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 (Figure 1, Table 6). ( 1, B-NR )
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 MR secondary to structural abnormalities of the mitral valve apparatus, or in the assessment of the feasibility of alcohol septal ablation. ( 2a, C-LD )
12. For patients with HCM in whom the diagnosis 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 CMR are not readily available or are contraindicated. ( 2a, B-NR )
13. For asymptomatic patients with HCM who do not have a resting or provocable outflow tract peak gradient ≥50 mm Hg on standard TTE, exercise TTE is reasonable for the detection and quantification of dynamic LVOTO. ( 2a, C-LD )
6.3. CMR Imaging
1. For patients suspected of having HCM in whom echocardiography is inconclusive, CMR imaging is indicated for diagnostic clarification. ( 1, B-NR )
2. For patients with left ventricular hypertrophy (LVH) in whom there is a suspicion of alternative diagnoses, including infiltrative or storage disease as well as athlete’s heart, CMR imaging is useful (Figure 1). ( 1, B-NR )
3. For patients with HCM who are not otherwise identified as high risk for SCD, or in whom a decision to proceed with ICD remains uncertain after clinical assessment that includes personal or family history, echocardiography, and ambulatory electrocardiographic monitoring, CMR imaging is beneficial to assess for maximum LV wall thickness, EF, LV apical aneurysm, and extent of myocardial replacement fibrosis with late gadolinium enhancement (LGE). ( 1, B-NR )
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. ( 1, B-NR )
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 LGE and other morphologic changes, including EF, development of apical aneurysm, or LV wall thickness (Figure 1, Table 7). ( 2b, C-EO )
6.4. Cardiac CT
1. In adult patients with suspected HCM, cardiac CT may be considered for diagnosis if the echocardiogram is not diagnostic and CMR imaging is unavailable. ( 2b, C-LD )
6.5. Heart Rhythm Assessment
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) (Figure 1, Table 6). ( 1, B-NR )
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 to guide management of arrhythmias (Figure 1). ( 1, B-NR )
3. In patients with HCM who develop palpitations or lightheadedness, extended (>24 hours) electrocardiographic monitoring or event recording is recommended for arrhythmia diagnosis and clinical correlation. ( 1, B-NR )
4. In first-degree relatives of patients with HCM, a 12-lead ECG is recommended as a component of the screening algorithm (Figure 1, Table 6). ( 1, B-NR )
5. In patients with HCM who are deemed to be at high risk for developing AF based on the presence of risk factors or as determined by a validated risk score, and who are eligible for anticoagulation, extended ambulatory monitoring is recommended to screen for AF as part of initial evaluation and annual follow-up (Figure 1). ( 1, B-NR )
6. 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). ( 2b, B-NR )
6.6. Angiography and Invasive Hemodynamic Assessment
1. For patients with symptomatic HCM for whom there is uncertainty regarding the presence or severity of LVOTO on noninvasive imaging studies, invasive hemodynamic assessment with cardiac catheterization is recommended. ( 1, B-NR )
2. In patients with HCM who have symptoms or evidence of myocardial ischemia, coronary angiography (CT or invasive) is recommended. ( 1, B-NR )
3. In patients with HCM who are at risk of coronary atherosclerosis, coronary angiography (CT or invasive) is recommended before surgical myectomy. ( 1, B-NR )
6.7. Exercise Stress Testing
1. For symptomatic patients with HCM who do not have resting or provocable outflow tract peak gradient ≥50 mm Hg on TTE, exercise TTE is recommended for the detection and quantification of dynamic LVOTO. ( 1, B-NR )
2. In patients with nonobstructive HCM and advanced HF (NYHA functional class III to class IV), cardiopulmonary exercise stress testing should be performed to quantify the degree of functional limitation and aid in selection of patients for heart transplantation or mechanical circulatory support. ( 1, B-NR )
3. In pediatric patients with HCM, regardless of symptom status, exercise stress testing is recommended to determine functional capacity and to provide prognostic information. ( 1, B-NR )
4. In adult patients with HCM, exercise stress testing is reasonable to determine functional capacity and to provide prognostic information as part of initial evaluation. ( 2a, B-NR )
5. For asymptomatic patients with HCM who do not have a resting or provocable outflow tract peak gradient ≥50 mm Hg on standard TTE, exercise TTE is reasonable for the detection and quantification of dynamic LVOTO. ( 2a, C-LD )
6. In patients with obstructive HCM and ambiguous functional capacity, exercise stress testing may be reasonable to guide therapy (Figure 1). ( 2b, C-LD )
7. In patients with HCM for whom it is unclear if their functional capacity has declined, exercise stress testing may be considered every 2 to 3 years (Figure 1). ( 2b, C-EO )
6.8. Genetics and Family Screening
1. In patients with HCM, evaluation of familial inheritance, including a 3-generation family history, is recommended as part of the initial assessment. ( 1, B-NR )
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). ( 1, B-NR )
3. In patients with an atypical clinical presentation of HCM or when another genetic condition is suspected to be the cause, a workup including genetic testing for HCM and other genetic causes of unexplained cardiac hypertrophy (“HCM phenocopies”) is recommended. ( 1, B-NR )
4. In patients with HCM, genetic counseling by an expert in the genetics of cardiovascular disease is recommended so that risks, benefits, test results, and their clinical significance can be reviewed and discussed with the patient in a shared decision-making process. ( 1, B-NR )
5. When performing genetic testing in a proband with HCM, the initial tier of genes tested should include genes with strong evidence to be disease-causing in HCM.* ( 1, B-NR )
* Strong evidence HCM genes include, at the time of this publication: MYH7, MYBPC3, TNNI3, TNNT2, TPM1, MYL2, MYL3, and ACTC1.
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. ( 1, B-NR )
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. ( 1, B-NR )
8. In patients with HCM who have undergone genetic testing, serial reevaluation of the clinical significance of the variant(s) identified is recommended to assess for variant reclassification, which may impact diagnosis and cascade genetic testing in family members (Figure 1, Figure 2). ( 1, B-NR )
9. In affected families with HCM, preconception and prenatal reproductive and genetic counseling should be offered. ( 1, B-NR )
10. In adult patients with HCM, the usefulness of genetic testing in the assessment of risk of SCD is uncertain. ( 2b, B-NR )
11. In patients with HCM who have a variant of uncertain significance (VUS), the usefulness of clinical genetic testing of phenotype-negative relatives for the purpose of variant reclassification is uncertain. ( 2b, B-NR )
12. For patients with HCM who have undergone genetic testing and were found to have no pathogenic variants (ie, harbor only benign or likely benign variants), cascade genetic testing of the family is not useful. ( 3 - No Benefit, B-NR )
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 a VUS, likely benign, or benign variant during follow-up. ( 3 - No Benefit, B-NR )
6.9. Individuals Who Are Genotype-Positive, Phenotype-Negative
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 (Figure 1, Figure 2, Table 6). ( 1, B-NR )
2. In individuals who are genotype-positive, phenotype-negative for HCM, participation in competitive sports of any intensity is reasonable. ( 2a, B-NR )
3. In individuals who are genotype-positive, phenotype-negative for HCM, ICD is not recommended for primary prevention. ( 3 - No Benefit, B-NR )
7. SCD Risk Assessment and Prevention
7.1. SCD Risk Assessment
7.1.1. SCD Risk Assessment in Adults With HCM
1. In adult patients with HCM, a comprehensive, systematic noninvasive SCD risk assessment at initial evaluation and every 1 to 2 years thereafter is recommended and should include evaluation of these risk factors (Figure 1, Figure 3, Table 7):
a. Personal history of cardiac arrest or sustained ventricular arrhythmias;
b. Personal history of syncope suspected by clinical history to be arrhythmic;
c. Family history in close relative of premature HCM-related sudden death, cardiac arrest, or sustained ventricular arrhythmias;
d. Maximal LV wall thickness, EF, LV apical aneurysm;
e. NSVT episodes on continuous ambulatory electrocardiographic monitoring.
( 1, B-NR )
2. For adult patients with HCM who are not otherwise identified as high risk for SCD, or in whom a decision to proceed with ICD placement remains uncertain after clinical assessment that includes personal/family history, echocardiography, and ambulatory electrocardiographic monitoring, CMR imaging is beneficial to assess for maximum LV wall thickness, EF, LV apical aneurysm, and extent of myocardial fibrosis with LGE (Table 7). ( 1, B-NR )
3. For patients who are ≥16 years of age with HCM, it is reasonable to obtain echocardiography-derived left atrial diameter and maximal LVOT gradient to aid in calculating an estimated 5-year sudden death risk that may be useful during shared decision-making for ICD placement (Table 7). ( 2a, B-NR )
7.1.2. SCD Risk Assessment in Children and Adolescents With HCM
1. For children and adolescents with HCM, a comprehensive, systematic noninvasive SCD risk assessment at initial evaluation and every 1 to 2 years thereafter is recommended and should include evaluation of these risk factors (Figure 1, Figure 3, Table 7):
a. Personal history of cardiac arrest or sustained ventricular arrhythmias;
b. Personal history of syncope suspected by clinical history to be arrhythmic;
c. Family history in close relative of premature HCM-related sudden death, cardiac arrest, or sustained ventricular arrhythmias;
d. Maximal LV wall thickness, EF, LV apical aneurysm;
e. NSVT episodes on continuous ambulatory electrocardiographic monitoring.
( 1, B-NR )
2. For children and adolescents with HCM who have a borderline risk for SCD, or in whom a decision to proceed with ICD placement remains uncertain after clinical assessment that includes personal and family history, echocardiography, and ambulatory electrocardiographic monitoring, CMR imaging is beneficial to assess for extent of myocardial fibrosis with LGE (Table 7). ( 1, C-LD )
3. For patients <16 years of age with HCM, it is reasonable to calculate an estimated 5-year sudden death risk that includes echocardiographic parameters (interventricular septal thickness in diastole, LV posterior wall thickness in end-diastole, left atrial diameter, maximal LVOT gradient) and genotype, which may be useful during shared decision-making for ICD placement (Table 7). ( 2a, B-NR )
7.2. Patient Selection for ICD Placement
1. In patients with HCM, application of individual clinical judgment is recommended when assessing the prognostic strength of conventional risk marker(s) within the clinical profile of the individual patient, as well as a thorough and balanced discussion of the evidence, benefits, and estimated risks to engage the fully informed patient’s active participation in ICD decision-making. ( 1, C-EO )
2. For patients with HCM and previous documented cardiac arrest or sustained VT, ICD placement is recommended (Figure 3, Table 7). ( 1, B-NR )
3. For adult patients with HCM with ≥1 major risk factors for SCD, it is reasonable to offer an ICD. These major risk factors include (Figure 3, Table 7):
a. Sudden death judged definitively or likely attributable to HCM in ≥1 first-degree or close relatives who are ≤50 years of age;
b. Massive LVH ≥30 mm in any LV segment;
c. ≥1 recent episodes of syncope suspected by clinical history to be arrhythmic (ie, unlikely to be of neurocardiogenic [vasovagal] etiology, or related to LVOTO);
d. LV apical aneurysm with transmural scar or LGE;
e. LV systolic dysfunction (EF <50%).
( 2a, B-NR )
4. For children with HCM who have ≥1 conventional risk factors, including unexplained syncope, massive LVH, NSVT, or family history of early HCM-related SCD, ICD placement is reasonable after considering the relatively high complication rates of long-term ICD placement in younger patients (Figure 3, Table 7). ( 2a, B-NR )
5. For patients with HCM with ≥1 major SCD risk factors, discussion of the estimated 5-year sudden death risk and mortality rates can be useful during the shared decision-making process for ICD placement (Figure 3, Table 7). ( 2a, B-NR )
6. In select adult patients with HCM and without major SCD risk factors after clinical assessment, or in whom the decision to proceed with ICD placement remains otherwise uncertain, ICD may be considered in patients with extensive LGE by contrast-enhanced CMR imaging or NSVT present on ambulatory monitoring (Figure 3, Table 7). ( 2b, B-NR )
7. In pediatric patients with HCM, it can be useful to consider additional factors such as extensive LGE on contrast-enhanced CMR imaging and systolic dysfunction in risk stratification for ICD shared decision-making (Figure 3, Table 7). ( 2b, B-NR )
8. In patients with HCM without risk factors, ICD placement should not be performed. ( 3 - Harm, B-NR )
9. In patients with HCM, ICD placement for the sole purpose of participation in competitive athletics should not be performed. ( 3 - Harm, B-NR )
7.3. ICD Device Selection Considerations
1. In patients with HCM who are receiving an ICD, either a single chamber transvenous ICD or a subcutaneous ICD is recommended after a shared decision-making discussion that takes into consideration patient preferences, age, lifestyle, and potential need for pacing for bradycardia or VT termination. ( 1, B-NR )
2. In patients with HCM who are receiving a transvenous ICD, single-coil ICD leads are recommended in preference to dualcoil leads, if defibrillation threshold is deemed adequate. ( 1, B-NR )
3. In patients with HCM who are receiving an ICD, dual-chamber ICDs are reasonable for patients with a need for atrial or atrioventricular sequential pacing for bradycardia/ conduction abnormalities, or as an attempt to relieve symptoms of obstructive HCM (most commonly in patients >65 years of age). ( 2a, B-NR )
4. In selected adult patients with nonobstructive HCM receiving an ICD who have NYHA class II to ambulatory class IV HF, left bundle branch block (LBBB), and LVEF <50%, cardiac resynchronization therapy (CRT) for symptom reduction is reasonable. ( 2a, C-LD )
5. In patients with HCM in whom a decision has been made for ICD implantation and who have paroxysmal atrial tachycardias or AF, dual-chamber ICDs may be reasonable, but this decision must be balanced against higher complication rates of dual-chamber devices. ( 2b, C-LD )
8. Management of HCM
8.1. Management of Symptomatic Patients With Obstructive HCM
8.1.1. Pharmacological Management of Symptomatic Patients With Obstructive HCM
1. In patients with obstructive
HCM and symptoms
* attributable to
LVOTO, nonvasodilating
beta blockers, titrated to effectiveness or maximally tolerated doses, are recommended.
( 1, B-NR )* Symptoms include effort-related dyspnea or chest pain and occasionally other exertional symptoms (eg, syncope, near syncope) that are attributed to LVOTO and interfere with everyday activity or quality of life.
2. In patients with obstructive
HCM and symptoms
* attributable to
LVOTO, for whom
beta blockers are ineffective or not tolerated, substitution with nondihydropyridine
calcium channel blockers are recommended.
* Symptoms include effort-related dyspnea or chest pain and occasionally other exertional symptoms (eg, syncope, near syncope) that are attributed to
LVOTO and interfere with everyday activity or quality of life.
† Symbol corresponds to the Level of Evidence for
verapamil.
‡ Symbol corresponds to the Level of Evidence for
diltiazem.
3. For patients with obstructive
HCM who have persistent symptoms
* attributable to
LVOTO despite
beta blockers or nondihydropyridine
calcium channel blockers, adding a myosin inhibitor (adult patients only), or
disopyramide (in combination with an atrioventricular nodal blocking agent), or
SRT performed at experienced centers,
§ is recommended.
( 1, B-R )* Symptoms include effort-related dyspnea or chest pain and occasionally other exertional symptoms (eg, syncope, near syncope) that are attributed to LVOTO and interfere with everyday activity or quality of life.
§ Comprehensive or primary HCM centers with demonstrated excellence in clinical outcomes for these procedures (Table 3, Table 4).
4. For patients with obstructive
HCM and acute hypotension who do not respond to fluid administration, intravenous
phenylephrine (or other
vasoconstrictors without inotropic activity), alone or in combination with beta-blocking drugs, is recommended.
( 1, C-LD ) 5. For patients with obstructive
HCM and persistent dyspnea with clinical evidence of volume overload and high left-sided filling pressures despite other
HCM GDMT, cautious use of low-dose oral
diuretics may be considered.
( 2b, C-EO ) 7. For patients with obstructive
HCM and severe dyspnea at rest, hypotension, very high resting gradients (eg, >100 mm Hg), as well as all children <6 weeks of age,
verapamil is potentially harmful.
( 3 - Harm, C-LD )
8.1.2. Invasive Treatment of Symptomatic Patients With Obstructive HCM
1. In patients with obstructive HCM who remain symptomatic despite GDMT, SRT in eligible patients,* performed at experienced HCM centers,† is recommended for relieving LVOTO (Table 3, Table 4). ( 1, B-NR )
2. In symptomatic patients with obstructive HCM who have associated cardiac disease requiring surgical treatment (eg, associated anomalous papillary muscle, markedly elongated anterior mitral leaflet, intrinsic mitral valve disease, multivessel CAD, valvular aortic stenosis), surgical myectomy, performed at experienced HCM centers,† is recommended (Table 3, Table 4). ( 1, B-NR )
3. In adult patients with obstructive HCM who remain severely symptomatic, despite GDMT and in whom surgery is contraindicated or the risk is considered unacceptable because of serious comorbidities or advanced age, alcohol septal ablation in eligible patients,* performed at experienced HCM centers,† is recommended (Table 3, Table 4). ( 1, C-LD )
4. In patients with obstructive HCM, earlier (NYHA class II) surgical myectomy performed at comprehensive HCM centers (Table 3, Table 4) may be reasonable in the presence of additional clinical factors, including:
a. Severe and progressive pulmonary hypertension thought to be attributable to LVOTO or associated MR;
b. Left atrial enlargement with ≥1 episodes of symptomatic AF;
c. Poor functional capacity attributable to LVOTO as documented on treadmill exercise testing;
d. Children and young adults with very high resting LVOT gradients (>100 mm Hg).
( 2b, B-NR )
5. For symptomatic patients with obstructive HCM, SRT in eligible patients,* performed at experienced HCM centers† (Table 3, Table 4), may be considered as an alternative to escalation of medical therapy after shared decision-making including risks and benefits of all treatment options. ( 2b, C-LD )
6. For patients with HCM who are asymptomatic and have normal exercise capacity, SRT is not recommended. ( 3 - Harm, C-LD )
7. For symptomatic patients with obstructive HCM in whom SRT is an option, mitral valve replacement should not be performed for the sole purpose of relief of LVOTO. ( 3 - Harm, B-NR )
* General eligibility criteria for septal reduction therapy: (a) Clinical: Severe dyspnea or chest pain (usually NYHA functional class III or class IV), or occasionally other exertional symptoms (eg, syncope, near syncope), when attributable to LVOTO, that interferes with everyday activity or quality of life despite optimal medical therapy; (b) Hemodynamic: Dynamic LVOT gradient at rest or with physiologic provocation with approximate peak gradient of ≥50 mm Hg, associated with septal hypertrophy and SAM of mitral valve; and (c) Anatomic: Targeted anterior septal thickness sufficient to perform the procedure safely and effectively in the judgment of the individual operator.
† Comprehensive or primary HCM centers with demonstrated excellence in clinical outcomes for these procedures (Table 3, Table 4).
8.2. Management of Patients With Nonobstructive HCM With Preserved EF
1. In patients with nonobstructive
HCM with preserved
EF and symptoms of exertional angina or dyspnea,
beta blockers or nondihydropyridine
calcium channel blockers are recommended.
( 1, C-LD ) 3. In patients with nonobstructive
HCM with preserved
EF, the usefulness of angiotensin-converting enzyme inhibitors and
angiotensin receptor blockers in the treatment of symptoms (angina and dyspnea) is not well established.
( 2b, C-LD ) 4. In highly selected patients with apical HCM with severe dyspnea or angina (NYHA class III or class IV) despite maximal medical therapy, and with preserved EF and small LV cavity size (LV end-diastolic volume <50 mL/m2 and LV stroke volume <30 mL/m2 ), apical myectomy by experienced surgeons at comprehensive centers may be considered to reduce symptoms. ( 2b, C-LD )
6. For younger (eg, ≤45 years of age) patients with nonobstructive
HCM due to a pathogenic or likely pathogenic cardiac sarcomere genetic variant, and a mild phenotype,
* valsartan may be beneficial to slow adverse cardiac remodeling.
( 2b, B-R ) * Mild phenotype indicates NYHA class I or II, maximal left ventricular wall thickness 13 to 25 mm, no secondary prevention ICDs, no history of appropriate ICD shocks, and no atrial fibrillation.
8.3. Management of Patients With HCM and Advanced HF
1. In patients with HCM who develop systolic dysfunction with an LVEF <50%, GDMT for HF with reduced EF is recommended. ( 1, C-LD )
2. In patients with HCM and systolic dysfunction, diagnostic testing to assess for concomitant causes of systolic dysfunction (eg, CAD) is recommended. ( 1, C-LD )
3. In patients with nonobstructive HCM and advanced HF (NYHA functional class III to class IV despite GDMT), CPET should be performed to quantify the degree of functional limitation and aid in selection of patients for heart transplantation or mechanical circulatory support. ( 1, B-NR )
4. In patients with nonobstructive HCM and advanced HF (NYHA class III to class IV despite GDMT) or with life-threatening ventricular arrhythmias refractory to maximal GDMT, assessment for heart transplantation in accordance with current listing criteria is recommended. ( 1, B-NR )
5. In patients with HCM who develop persistent systolic dysfunction (LVEF <50%), cardiac myosin inhibitors should be discontinued. ( 1, B-R )
6. For patients with
HCM who develop systolic dysfunction (
LVEF <50%), it is reasonable to discontinue previously indicated negative inotropic agents (specifically,
verapamil,
diltiazem, or
disopyramide).
( 2a, C-EO ) 7. In patients with nonobstructive HCM and advanced HF (NYHA functional class III to class IV despite GDMT) who are candidates for heart transplantation, continuous-flow LVAD therapy is reasonable as a bridge to heart transplantation. ( 2a, B-NR )
8. In patients with HCM and persistent LVEF <50%, ICD placement can be beneficial. ( 2a, C-LD )
9. In patients with HCM and LVEF <50%, NYHA functional class II to class IV symptoms despite GDMT, and LBBB, CRT can be beneficial to improve symptoms. ( 2a, C-LD )
8.4. Management of Patients With HCM and AF
1. In patients with
HCM and clinical
AF, anticoagulation is recommended with DOACs as first-line option and
vitamin K antagonists as second-line option, independent of CHA
2DS
2-VASc score.
( 1, B-NR ) 2. In patients with
HCM and subclinical
AF detected by internal or external cardiac device or monitor of >24 hours’ duration for a given episode, anticoagulation is recommended with DOACs as first-line option and
vitamin K antagonists as second-line option, independent of CHA
2DS
2-VASc score.
( 1, C-LD ) 3. In patients with
AF in whom rate control strategy is planned, either
beta blockers,
verapamil, or
diltiazem are recommended, with the choice of agents according to patient preferences and comorbid conditions.
( 1, C-LD ) 4. In patients with
HCM and subclinical
AF detected by internal or external device or monitor, of >5 minutes’ duration but <24 hours’ duration for a given episode, anticoagulation with DOACs as first-line option and
vitamin K antagonists as second-line option can be beneficial, taking into consideration duration of
AF episodes, total
AF burden, underlying risk factors, and bleeding risk.
( 2a, C-LD ) 5. In patients with HCM and poorly tolerated AF, a rhythm-control strategy with cardioversion or antiarrhythmic drugs can be beneficial with the choice of an agent according to AF symptom severity, patient preferences, and comorbid conditions. ( 2a, B-NR )
6. In patients with HCM and symptomatic AF, as part of an AF rhythm-control strategy, catheter ablation for AF can be effective when drug therapy is ineffective, contraindicated, or not the patient’s preference. ( 2a, B-NR )
7. In patients with HCM and AF who require surgical myectomy, concomitant surgical AF ablation procedure can be beneficial for AF rhythm control. ( 2a, B-NR )
8.5. Management of Patients With HCM and Ventricular Arrhythmias
1. In patients with HCM and recurrent, poorly tolerated life-threatening ventricular tachyarrhythmias refractory to maximal antiarrhythmic drug therapy and ablation, heart transplantation assessment is indicated in accordance with current listing criteria. ( 1, B-NR )
2. In adults with HCM and symptomatic ventricular arrhythmias or recurrent ICD shocks despite beta-blocker use, antiarrhythmic drug therapy like
dofetilide, mexiletine, or sotalol ( 1, C-LD )
is recommended, with the choice of agent guided by age, underlying comorbidities, severity of disease, patient preferences, and balance between efficacy and safety.
3. In children with HCM and recurrent ventricular arrhythmias despite beta-blocker use, antiarrhythmic drug therapy (eg, amiodarone, mexiletine, sotalol) is recommended, with the choice of agent guided by age, underlying comorbidities, severity of disease, patient preferences, and balance of efficacy and safety. ( 1, C-LD )
4. In patients with HCM and pacing-capable ICDs, programming antitachycardia pacing is recommended to minimize risk of shocks. ( 1, C-LD )
5. In patients with HCM and recurrent symptomatic sustained monomorphic VT, or recurrent ICD shocks despite optimal device programming, and in whom antiarrhythmic drug therapy is either ineffective, not tolerated, or not preferred, catheter ablation can be useful for reducing arrhythmia burden. ( 2a, C-LD )
9. Lifestyle Considerations for Patients With HCM
9.1. Recreational Physical Activity and Competitive Sports
1. For patients with HCM, mild- to moderate-intensity* recreational† exercise is beneficial to improve cardiorespiratory fitness, physical functioning, and quality of life, and for overall health in keeping with physical activity guidelines for the general population. ( 1, B-R )
2. For athletes with HCM, a comprehensive evaluation and shared decision-making about sports participation with an expert professional is recommended. ( 1, C-EO )
3. In individuals who are genotype-positive, phenotype-negative for HCM, participation in competitive sports of any intensity is reasonable. ( 2a, B-NR )
4. For patients with HCM, participation in vigorous* recreational activities is reasonable after an annual comprehensive evaluation and shared decision-making with an expert professional who balances potential benefits and risks. ( 2a, B-NR )
5. For patients with HCM who are capable of a high level of physical performance, participation in competitive sports† may be considered after review by an expert provider with experience managing athletes with HCM who conducts an annual comprehensive evaluation and shared decision-making that balances potential benefits and risks. ( 2b, B-NR )
6. For most patients with HCM, universal restriction from vigorous physical activity or competitive sports is not indicated. ( 3 - No Benefit, B-NR )
7. In patients with HCM, ICD placement for the sole purpose of participation in competitive sports should not be performed. ( 3 - Harm, C-EO )
* Exercise intensity can be gauged by METS: light <3 METs, moderate 3–6 METs, and vigorous >6 METs, by % maximum heart rate achieved (light 40%–50%, moderate 50%–70%, vigorous >70%), or by level of perceived exertion on the Borg scale (light 7–12, moderate 13–14, vigorous ≥15).
† Recreational exercise is done for the purpose of leisure with no requirement for systematic training and without the purpose to excel or compete against others. Competitive sports involve systematic training for the primary purpose of competition against others, at multiple levels, including high school, collegiate, master’s level, semiprofessional, or professional sporting activities.
9.2. Occupation in Patients With HCM
1. For patients with HCM, it is reasonable to follow Federal Motor Carrier Safety Administration cardiovascular disease guidelines that permit driving commercial motor vehicles, if they do not have an ICD or any major risk factors for SCD and are using a GDMT plan. ( 2a, C-EO )
2. For pilot aircrew with a diagnosis of HCM, it is reasonable to follow Federal Aviation Administration guidelines that permit consideration of multicrew flying duties, provided they are asymptomatic, are deemed low risk for SCD, and can complete a maximal treadmill stress test at 85% peak heart rate. ( 2a, C-EO )
3. It is reasonable for patients with HCM to consider occupations that require manual labor, heavy lifting, or a high level of physical performance after a comprehensive clinical evaluation, risk stratification for SCD, and implementation of GDMT in the context of shared decision-making. ( 2b, C-EO )
9.3. Pregnancy in Patients With HCM
1. For pregnant women with
HCM and
AF or other indications for anticoagulation, low-molecular-weight heparin or
vitamin K antagonists (at maximum therapeutic dose of <5 mg daily) are recommended for stroke prevention.
( 1, B-NR ) 2. In pregnant women with
HCM, selected
beta blockers should be administered for symptoms related to outflow tract obstruction or arrhythmias, with monitoring of fetal growth.
( 1, C-LD ) 3. In most pregnant women with HCM, vaginal delivery is recommended as the first-choice delivery option. ( 1, C-LD )
4. In affected families with HCM, preconceptional and prenatal reproductive and genetic counseling should be offered. ( 1, B-NR )
5. For pregnant women with HCM, care should be coordinated between their cardiologist and an obstetrician. For patients with HCM who are deemed high risk, consultation is advised with an expert in maternal-fetal medicine. ( 1, C-EO )
6. For women with clinically stable HCM who wish to become pregnant, it is reasonable to advise that pregnancy is generally safe as part of a shared discussion regarding potential maternal and fetal risks, and initiation of GDMT. ( 2a, C-LD )
7. In pregnant women with HCM, cardioversion for new or recurrent AF, particularly if symptomatic, is reasonable. ( 2a, C-LD )
8. In pregnant women with HCM, general or epidural anesthesia is reasonable, with precautions to avoid hypotension. ( 2a, C-LD )
9. In pregnant women with HCM, it is reasonable to perform serial echocardiography, particularly during the second or third trimester when hemodynamic load is highest, or if clinical symptoms develop. ( 2a, C-EO )
10. In pregnant women with HCM, fetal echocardiography may be considered for diagnosis of fetal HCM in the context of prenatal counseling. ( 2b, C-EO )
11. In pregnant women, use of mavacamten is contraindicated due to potential teratogenic effects. ( 3 - Harm, C-EO )
9.4. Patients With Comorbidities
1. In patients with HCM, adherence to the ACC/AHA primary prevention guideline is recommended to reduce risk of cardiovascular events. ( 1, C-EO )
2. In patients with HCM who are overweight or obese, counseling and comprehensive lifestyle interventions are recommended for achieving and maintaining weight loss and possibly lowering the risk of developing LVOTO, HF, and AF. ( 1, B-NR )
3. In patients with
HCM and hypertension, lifestyle modifications and medical therapy for hypertension are recommended, with preference for
beta blockers and nondihydropyridine
calcium channel blockers in patients with obstructive
HCM.
( 1, C-LD ) 4. In patients with HCM, assessment for symptoms of sleep-disordered breathing is recommended and, if present, referral to a sleep medicine specialist for evaluation and treatment is recommended. ( 1, C-LD )
Class of Recommendations and Level of Evidence
COR and LOE are determined independently (any COR may be paired with any LOE).
A recommendation with LOE C does not imply that the recommendation is weak. Many important clinical questions addressed in guidelines do not lend themselves to clinical trials. Although RCTs are unavailable, there may be a very clear clinical consensus that a particular test or therapy is useful or effective.
* The outcome or result of the intervention should be specified (an improved clinical outcome or increased diagnostic accuracy or incremental prognostic information).
† For comparative-effectiveness recommendations (COR I and IIa; LOE A and B only), studies that support the use of comparator verbs should involve direct comparisons of the treatments or strategies being evaluated.
‡ The method of assessing quality is evolving, including the application of standardized, widely used, and preferably validated evidence grading tools; and for systematic reviews, the incorporation of an Evidence Review Committee.
COR indicates Class of Recommendation; EO, expert opinion; LD, limited data; LOE, Level of Evidence; NR, nonrandomized; R, randomized; RCT, randomized controlled trial.