What are the current management guidelines for hypertrophic cardiomyopathy, including pharmacologic therapy, septal reduction, sudden cardiac death risk stratification, lifestyle recommendations, and emerging treatments?

Management of Hypertrophic Cardiomyopathy

For symptomatic patients with obstructive HCM, initiate nonvasodilating beta-blockers titrated to a resting heart rate of 60-65 bpm as first-line therapy, and if symptoms persist despite optimal dosing, add mavacamten as second-line therapy before considering septal reduction procedures. 1, 2

Pharmacologic Management Algorithm

First-Line Therapy for Obstructive HCM

• Nonvasodilating beta-blockers are the Class I recommended initial treatment for all symptomatic patients with obstructive HCM, regardless of gradient severity, titrated to effectiveness or maximally tolerated doses 1, 2
• Target resting heart rate of 60-65 bpm to reduce LVOT gradients, alleviate dyspnea, and improve quality of life 2
• If beta-blockers are ineffective or not tolerated, substitute with non-dihydropyridine calcium channel blockers (verapamil up to 480 mg/day or diltiazem) 1, 3

Critical contraindication: Verapamil is potentially harmful in patients with severe dyspnea at rest, hypotension, very high resting gradients (>100 mm Hg), and all children <6 weeks of age 1

Second-Line Therapy Options

• Mavacamten (cardiac myosin inhibitor) is now a Class I recommendation for adults with persistent NYHA class II-III symptoms despite optimal beta-blocker or calcium channel blocker therapy 2, 4
• Mavacamten improves LVOT gradients, functional capacity, and quality of life in 30-60% of patients 2, 4
• Mandatory REMS program monitoring required: Interrupt treatment if LVEF falls <50% at any visit (occurs in 5.7% of patients) 3, 4
• Absolute contraindication in pregnancy due to teratogenic effects; negative pregnancy test mandatory before initiation in women of childbearing potential 3, 4

Third-Line Pharmacologic Option

• Disopyramide in combination with an AV nodal blocking agent (beta-blocker or calcium channel blocker) for patients who remain severely symptomatic despite first-line therapy 1, 2
• This combination is recommended before proceeding to septal reduction therapy 1

Medications to AVOID (Class III: Harm)

Discontinue all vasodilators immediately in patients with obstructive HCM, as they worsen LVOT obstruction 2:

• ACE inhibitors and ARBs 2
• Dihydropyridine calcium channel blockers (nifedipine, amlodipine) 2
• Digoxin 1
• Alpha-blockers, nitrates, and hydralazine 2

Septal Reduction Therapy

Indications for Septal Reduction

Septal reduction therapy is recommended for patients with 1:

• Severe dyspnea or chest pain (NYHA class III or IV) attributable to LVOTO that interferes with everyday activity despite optimal medical therapy 1
• Peak LVOT gradient ≥50 mm Hg at rest or with physiologic provocation 1
• Sufficient anterior septal thickness to perform the procedure safely 1

Procedures must be performed at experienced comprehensive or primary HCM centers with demonstrated excellence in clinical outcomes 1

Contraindications for Septal Reduction

• Asymptomatic patients with normal exercise capacity should NOT undergo septal reduction therapy (Class III: Harm) 1
• Mitral valve replacement should not be performed for the sole purpose of relieving LVOTO 1

Management of Nonobstructive HCM

Symptomatic Patients with Preserved EF

• Beta-blockers or non-dihydropyridine calcium channel blockers are recommended for exertional angina or dyspnea 1
• Add oral diuretics when exertional dyspnea persists despite beta-blockers or calcium channel blockers 1
• ACE inhibitors and ARBs have uncertain benefit for symptom relief in nonobstructive HCM 1

Asymptomatic Patients

• The benefit of beta-blockers or calcium channel blockers is not well established in asymptomatic nonobstructive HCM 1

Atrial Fibrillation Management

All patients with HCM and atrial fibrillation require anticoagulation, independent of CHA₂DS₂-VASc score 1, 2:

• Direct-acting oral anticoagulants (DOACs) are first-line 1
• Vitamin K antagonists are second-line 1
• This applies to both clinical AF and subclinical AF detected by cardiac monitoring >24 hours duration 1

For rate control, use beta-blockers, verapamil, or diltiazem 1

Sudden Cardiac Death Risk Stratification

All patients with HCM require SCD risk stratification using major noninvasive risk markers to identify ICD candidates 2:

Major Risk Factors for ICD Consideration 1

• Family history of HCM-related sudden cardiac death
• Unexplained syncope
• Nonsustained ventricular tachycardia on ambulatory monitoring
• Massive left ventricular hypertrophy (wall thickness ≥30 mm)
• Left ventricular ejection fraction <50%

In patients >16 years of age, 5-year SCD risk estimates can guide shared decision-making for ICD placement 1

Lifestyle and Activity Recommendations

Exercise Restrictions

• Patients with HCM are traditionally disqualified from competitive sports due to sudden cardiac death risk during strenuous physical activity 5
• However, complete avoidance of physical activity has negative consequences including increased cardiovascular events and reduced wellbeing 5
• Shared decision-making is essential to develop individualized activity plans that balance SCD risk with quality of life benefits 1

Cardiometabolic Risk Factor Management

Intensive management of obesity and hypertension is essential, as these factors are present in >70% of adult HCM patients and independently associated with increased LV hypertrophy burden, more symptoms, and worse outcomes 2

Acute Management Considerations

For patients with obstructive HCM and acute hypotension not responding to fluids, intravenous phenylephrine (or other vasoconstrictors without inotropic activity), alone or in combination with beta-blockers, is recommended 1

Low-dose oral diuretics may be considered cautiously for patients with persistent dyspnea and clinical evidence of volume overload despite guideline-directed therapy 1

Multidisciplinary Care

Referral to comprehensive or primary HCM centers is reasonable for complex disease-related management decisions, including 1:

• Interpretation of genetic testing
• Primary prevention ICD decisions
• Septal reduction therapy evaluation
• Management of refractory symptoms