What is the initial treatment for hypertrophic cardiomyopathy?

Initial Treatment for Hypertrophic Cardiomyopathy

For patients with hypertrophic cardiomyopathy (HCM) presenting with symptoms such as exertional angina or dyspnea, beta-blockers or non-dihydropyridine calcium channel blockers are recommended as first-line therapy. 1, 2

Treatment Algorithm Based on Clinical Presentation

For Symptomatic Patients with Obstructive HCM:

1. First-line therapy:

   • Non-vasodilating beta-blockers (e.g., metoprolol, atenolol, propranolol)
   • Target: Reduce heart rate, prolong diastolic filling, improve myocardial contractile protein inactivation 2

2. Alternative first-line therapy (if beta-blockers are contraindicated or not tolerated):

   • Non-dihydropyridine calcium channel blockers (verapamil or diltiazem)
   • Caution: Use with care in patients with severe obstruction or elevated pulmonary artery pressures 2

3. Add-on therapy (if symptoms persist despite beta-blockers):

   • Disopyramide (Class I recommendation, Level B evidence) 2
   • Monitoring requirements: QTc interval (reduce dose if >480 ms)
   • Contraindications: Glaucoma, prostatism, concurrent QT-prolonging drugs

4. For persistent symptoms despite optimal medical therapy:

   • Consider septal reduction therapy (surgical myectomy preferred for younger patients)
   • Alcohol septal ablation as alternative for older patients or those with contraindications to surgery 2

For Symptomatic Patients with Non-obstructive HCM:

1. First-line therapy:

   • Beta-blockers or non-dihydropyridine calcium channel blockers 1

2. For persistent dyspnea:

   • Consider adding oral diuretics (use cautiously) 2

3. For highly selected patients with apical HCM with severe symptoms:

   • Apical myectomy may be considered in specialized centers 1

Special Considerations

Medication Precautions:

• Contraindicated medications:

  • Digoxin (worsens LVOT obstruction)
  • Dihydropyridine calcium channel blockers (e.g., nifedipine) 2
  • ACE inhibitors and ARBs (benefit not well established) 1

• Verapamil cautions:

  • Avoid in patients with severe LV dysfunction (EF <30%)
  • Avoid concomitant use with beta-blockers unless carefully monitored
  • Monitor for hypotension, AV block, and heart failure 3

Management of Comorbidities:

• Atrial fibrillation:

  • Anticoagulation with direct-acting oral anticoagulants (first-line) or vitamin K antagonists (second-line), regardless of CHA₂DS₂-VASc score 1
  • Rate control: Beta-blockers, verapamil, or diltiazem based on patient preference and comorbidities 1

• Ventricular arrhythmias:

  • Antiarrhythmic drug therapy for symptomatic ventricular arrhythmias or recurrent ICD shocks despite beta-blocker use 1
  • In children with recurrent ventricular arrhythmias: amiodarone, mexiletine, or sotalol 1

Monitoring Recommendations

• Transthoracic echocardiogram every 1-2 years to assess:

  • Degree of myocardial hypertrophy
  • Dynamic LVOT obstruction
  • Mitral regurgitation
  • Myocardial function 2

• 12-lead ECG and 24-48 hour ambulatory monitoring:

  • At initial evaluation and every 1-2 years 2

Lifestyle Modifications

• Avoid dehydration and excess alcohol consumption
• Weight management for overweight patients
• Low-intensity aerobic exercise is reasonable
• Evaluate and treat sleep apnea if present 2

The treatment of HCM has evolved significantly, with strong evidence supporting the use of beta-blockers or calcium channel blockers as initial therapy for symptomatic patients, with additional medications and interventions based on symptom persistence and disease characteristics.