Latest Guidelines for HOCM Treatment
For symptomatic HOCM, start with beta-blockers as first-line therapy, add myosin inhibitors (mavacamten) or disopyramide if symptoms persist, and reserve septal reduction therapy for severe drug-refractory cases—this represents the most significant update from the 2024 AHA/ACC guidelines. 1
First-Line Pharmacological Management
Beta-blockers are the cornerstone of initial therapy for all symptomatic HOCM patients, targeting a resting heart rate below 60-65 bpm. 2, 3 Non-vasodilating beta-blockers (e.g., metoprolol, atenolol) should be titrated to maximum tolerated doses to reduce myocardial oxygen demand and improve diastolic filling time. 3
For patients who cannot tolerate beta-blockers or have contraindications, non-dihydropyridine calcium channel blockers (verapamil or diltiazem) are the recommended alternative, starting at low doses and titrating up to 480 mg/day. 2, 4 However, verapamil is potentially harmful in patients with severe dyspnea at rest, hypotension, very high resting gradients (>100 mm Hg), or in children <6 weeks of age. 1, 4
Second-Line Therapy for Persistent Symptoms
The 2024 guidelines introduced a major change: for patients with persistent symptoms despite beta-blockers or calcium channel blockers, you now have three Class 1 recommendations: add a myosin inhibitor (mavacamten in adults), add disopyramide (with AV nodal blocking agent), or proceed to septal reduction therapy. 1 This represents a significant shift from the 2020 guidelines, which only recommended disopyramide or septal reduction therapy. 1
Myosin Inhibitors (Mavacamten)
- Mavacamten is now a Class 1 recommendation for adult patients with obstructive HCM and persistent symptoms despite first-line therapy. 1
- It lowers LVOT gradients and improves quality of life. 5
- Critical caveat: In 7-10% of patients, mavacamten causes reversible reduction of LVEF to <50%, requiring discontinuation. 5
- Mavacamten is contraindicated in pregnancy due to teratogenic effects. 1
- If systolic dysfunction develops (LVEF <50%), cardiac myosin inhibitors must be discontinued immediately. 1
Disopyramide
- Disopyramide should be combined with beta-blockers or verapamil (never as monotherapy), titrated to 400-600 mg/day in divided doses. 2, 4
- Monitor QTc interval during titration; reduce dose if QTc exceeds 480 ms. 2
- Avoid in patients with glaucoma, prostatism, or those taking other QT-prolonging medications (amiodarone, sotalol). 2
- Never use disopyramide as monotherapy in atrial fibrillation patients, as it may enhance AV conduction and increase ventricular rate. 2
Invasive Septal Reduction Therapy
For patients with severe symptoms (typically NYHA Class III-IV) despite optimal medical therapy, septal reduction therapy (SRT) at experienced centers is recommended. 1, 4
Patient Selection Criteria for SRT:
- Severe dyspnea or chest pain interfering with daily activities despite optimal medical therapy 1
- LVOT gradient ≥50 mm Hg at rest or with provocation 1
- Performed only at experienced centers with demonstrated excellence 1
Surgical Myectomy vs. Alcohol Septal Ablation:
Surgical myectomy is the gold standard and is recommended for: 1
Alcohol septal ablation is recommended for: 1
Earlier intervention (NYHA Class II) may be reasonable in specific circumstances: 1
- Severe progressive pulmonary hypertension attributable to LVOTO 1
- Left atrial enlargement with ≥1 episodes of symptomatic atrial fibrillation 1
- Poor functional capacity on treadmill exercise testing 1
- Children and young adults with very high resting LVOT gradients (>100 mm Hg) 1
Critical Medications to Avoid
Dihydropyridine calcium channel blockers (nifedipine, amlodipine) are potentially harmful in HOCM and should not be used. 2, 3 They cause vasodilation that worsens LVOT obstruction. 2
Vasodilators (ACE inhibitors, ARBs) and digoxin should be discontinued or avoided, as they can worsen symptoms by reducing afterload or increasing contractility. 1, 3
High-dose diuretics should be avoided, but cautious use of low-dose oral diuretics may be considered in patients with persistent dyspnea and clinical evidence of volume overload despite other therapies. 1, 4
Management of Atrial Fibrillation
All HOCM patients with atrial fibrillation require anticoagulation with direct oral anticoagulants (or warfarin) regardless of CHA₂DS₂-VASc score, due to inherently high stroke risk. 1, 3 This is a Class 1 recommendation reflecting the unique thrombotic risk in HCM. 1
Acute Management of Hypotension
For acute hypotension in HOCM patients, administer intravenous fluids first; if no response, use intravenous phenylephrine or other vasoconstrictors without inotropic activity, alone or combined with beta-blockers. 1, 4 Avoid inotropic agents that worsen obstruction. 1
Special Populations
Nonobstructive HCM with Preserved EF:
For younger patients (≤45 years) with nonobstructive HCM due to pathogenic sarcomeric variants and mild phenotype, valsartan may be beneficial to slow adverse cardiac remodeling (Class 2b). 1 This is a new 2024 recommendation. 1
Exercise and Physical Activity:
The 2024 guidelines shifted away from universal restriction: for most HOCM patients, universal restriction from vigorous physical activity or competitive sports is not indicated (Class 3: No Benefit). 1 Instead, participation in vigorous recreational activities is reasonable after annual comprehensive evaluation and shared decision-making with an expert provider (Class 2a). 1
Common Pitfalls to Avoid
Never perform SRT in asymptomatic patients with normal exercise capacity, regardless of gradient severity—this provides no benefit and carries procedural risks. 1
Never use mitral valve replacement as the sole procedure for LVOT obstruction relief—this is potentially harmful. 1
Never use disopyramide as monotherapy without AV nodal blocking agents, especially in atrial fibrillation patients. 2
Always discontinue myosin inhibitors if LVEF drops below 50%. 1
Monitor QTc intervals when using disopyramide and avoid combining with other QT-prolonging drugs. 2
Multidisciplinary Care and Referral
Refer to specialized HCM centers for: 1