What is the treatment for Hypertrophic Obstructive Cardiomyopathy (HOCM)?

Treatment of Hypertrophic Obstructive Cardiomyopathy (HOCM)

Beta blockers are the first-line pharmacologic treatment for symptomatic HOCM patients, with surgical septal myectomy being the gold standard invasive therapy for those with severe drug-refractory symptoms and significant left ventricular outflow tract obstruction (LVOTO). 1

Pharmacologic Management

First-Line Therapy

• Beta blockers (metoprolol, propranolol, atenolol) should be titrated to a resting heart rate of less than 60-65 bpm to reduce symptoms of angina, dyspnea, and palpitations 1
• Target dose should be the maximum tolerated dose within recommended ranges to achieve optimal symptom control 1

Second-Line Therapy

• Non-dihydropyridine calcium channel blockers (verapamil, diltiazem) are recommended for patients who:
  • Do not respond to beta blockers
  • Have side effects from beta blockers
  • Have contraindications to beta blockers 1
• Verapamil should be started at low doses and titrated up to 480 mg/day as needed 1
• Caution: Verapamil should be used carefully in patients with high gradients (>80-100 mmHg), advanced heart failure, or sinus bradycardia 1, 2

Third-Line Therapy

• Disopyramide can be combined with beta blockers or verapamil for persistent symptoms in patients with obstructive HCM 1
• Important: Disopyramide should not be used alone in patients with atrial fibrillation as it may enhance atrioventricular conduction 1

Adjunctive Therapy

• Low-dose oral diuretics may be added cautiously when congestive symptoms persist despite first-line medications 1
• For acute hypotension in obstructive HCM, intravenous phenylephrine or other pure vasoconstricting agents are recommended 1, 3

Medications to Avoid in HOCM

• Dihydropyridine calcium channel blockers (nifedipine, etc.) - can worsen LVOT obstruction 1
• Positive inotropic agents (dopamine, dobutamine, norepinephrine) - can precipitate hemodynamic collapse 1, 3
• Digitalis - harmful for treating dyspnea in HCM without atrial fibrillation 1
• ACE inhibitors and ARBs - potentially harmful in patients with resting or provocable LVOT obstruction 1
• Verapamil - harmful in setting of systemic hypotension or severe dyspnea at rest 1, 2

Invasive Treatment Options

Indications for Septal Reduction Therapy

• Severe drug-refractory symptoms (typically NYHA class III-IV) 1
• Dynamic LVOT gradient ≥50 mmHg at rest or with provocation 1
• Adequate septal thickness to safely perform the procedure 1

Surgical Septal Myectomy

• First consideration for most eligible patients with severe symptoms and LVOT obstruction 1
• Should be performed at experienced centers with cumulative case volumes of at least 50 procedures 1
• Particularly beneficial for:
  • Younger patients
  • Patients with greater septal thickness
  • Those with concomitant cardiac disease requiring surgery 1, 4
• Mortality rate <1% at experienced centers 4

• 90% of patients experience improvement by at least two functional classes 4

Alcohol Septal Ablation

• Alternative for patients when surgery is contraindicated or risk is unacceptable due to:
  • Advanced age
  • Significant comorbidities 1, 5
• Should only be performed by experienced operators at dedicated HCM centers 1
• Creates an intramyocardial scar that may potentially increase risk of ventricular arrhythmias 6

Special Considerations

• Children and adolescents may benefit from beta blockers but should be monitored for side effects including depression, fatigue, and impaired scholastic performance 1
• In perioperative settings, continue negative inotropic agents and avoid factors that worsen LVOT obstruction (tachycardia, reduced preload, reduced afterload) 3
• For patients with midventricular obstruction, transapical myectomy may be considered 4

Treatment Algorithm

1. Start with beta blockers, titrate to maximum tolerated dose
2. If symptoms persist, switch to or add non-dihydropyridine calcium channel blockers
3. For continued symptoms, add disopyramide (with beta blocker or calcium channel blocker)
4. Consider cautious addition of low-dose diuretics for persistent congestive symptoms
5. For severe drug-refractory symptoms with LVOT gradient ≥50 mmHg, refer to experienced center for septal reduction therapy evaluation
6. Surgical myectomy is preferred for most patients; alcohol septal ablation for those at high surgical risk