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

Treatment of Hypertrophic Obstructive Cardiomyopathy (HOCM)

Beta-blockers are the first-line treatment for symptomatic HOCM, titrated aggressively to achieve a resting heart rate below 60-65 bpm before considering treatment failure. 1

Initial Medical Management

First-Line: Beta-Blockers

• Start non-vasodilating beta-blockers (metoprolol, propranolol, or atenolol) and titrate to maximum tolerated doses, targeting resting heart rate <60-65 bpm. 1, 2
• Beta-blockers reduce LVOT obstruction through negative inotropic and chronotropic effects, improving diastolic filling time and reducing myocardial oxygen demand. 1
• Critical pitfall: Do not declare beta-blocker failure until adequate dosing achieves physiologic beta-blockade (demonstrated by resting heart rate suppression). 1, 3
• Common side effects include bradycardia, hypotension, and in children/adolescents, depression, fatigue, or impaired scholastic performance. 4

Second-Line: Calcium Channel Blockers

• If beta-blockers are ineffective, not tolerated, or contraindicated, use verapamil starting at low doses and titrating up to 480 mg/day. 1, 2
• Verapamil provides relief through negative inotropic and chronotropic effects similar to beta-blockers. 1
• Use verapamil with extreme caution in patients with high gradients (≥50 mmHg), advanced heart failure, or sinus bradycardia—it is potentially harmful in these settings. 4, 2
• Never combine beta-blockers with verapamil or diltiazem due to risk of high-grade AV block. 1, 3

Medications to Eliminate Immediately

Discontinue all vasodilators immediately, as they worsen LVOT obstruction and symptoms: 1

• Dihydropyridine calcium channel blockers (nifedipine) are potentially harmful in patients with resting or provocable LVOT obstruction. 4, 2
• ACE inhibitors and ARBs are potentially harmful in obstructive HCM and should be avoided. 4, 1
• Digitalis is potentially harmful in HCM patients without atrial fibrillation. 4, 2
• Avoid high-dose diuretics that promote obstruction through volume depletion. 1

Treatment for Refractory Symptoms

Add Disopyramide

• Combine disopyramide (400-600 mg/day) with beta-blocker or verapamil for patients who don't respond to first-line therapy alone. 1, 2
• Never use disopyramide as monotherapy—it may enhance AV conduction and increase ventricular rate during atrial fibrillation episodes. 4, 2
• Monitor QTc interval during dose titration and reduce dose if QTc exceeds 480 ms. 2
• Avoid in patients with glaucoma, prostatism, or those taking other QT-prolonging medications (amiodarone, sotalol). 2

Cautious Diuretic Use

• Low-dose oral diuretics may be added cautiously only if congestive symptoms persist despite optimal beta-blocker or verapamil therapy. 1, 2
• Use with extreme caution in obstructive HCM to avoid worsening LVOT obstruction through volume depletion. 4

Mavacamten (Newer Option)

• Consider mavacamten (cardiac myosin inhibitor) in adults with refractory symptoms—it improves gradients and symptoms in 30-60% of patients. 1
• Monitor for reversible LVEF reduction <50% (occurs in 7-10% of patients), requiring temporary discontinuation. 1

Septal Reduction Therapy for Severe Refractory Cases

Septal reduction therapy should be performed only at experienced comprehensive HCM centers for severely symptomatic patients despite optimal medical therapy with LVOT gradients ≥50 mmHg. 4, 2

Surgical Septal Myectomy

• Surgical myectomy is the first consideration and gold standard for most eligible patients, providing >90% relief of obstruction with <1% perioperative mortality at experienced centers. 1, 5
• Myectomy offers more complete and lasting reduction of LVOT obstruction compared to alcohol ablation. 6

Alcohol Septal Ablation

• Alcohol septal ablation is a less invasive alternative with comparable hemodynamic and clinical results in many patients. 5
• Results depend on septal perforator artery anatomy—younger patients with severe hypertrophy may not experience complete relief. 5

Critical Contraindication

• Never perform septal reduction therapy in asymptomatic patients with normal exercise capacity, regardless of gradient severity—there is no benefit and potential harm. 1, 2

Acute Management Considerations

Acute Hypotension

• Use intravenous phenylephrine (pure vasoconstrictor) for acute hypotension not responding to fluid administration. 4, 3
• Never use dopamine, dobutamine, norepinephrine, or other positive inotropes—they are potentially harmful in obstructive HCM. 4

Atrial Fibrillation/Flutter

• Initiate anticoagulation immediately in all HOCM patients with atrial fibrillation, regardless of CHA₂DS₂-VASc score. 1, 3
• For acute rate control: metoprolol 2.5-5 mg IV bolus over 2 minutes, repeatable up to 3 doses, targeting heart rate <60-65 bpm. 3
• Administer cautious IV fluid boluses (250-500 mL normal saline over 30-60 minutes) if hypotension develops, avoiding aggressive fluid resuscitation. 3

Key Clinical Pearls

• Success is determined by symptom response, not measured gradient—LVOT obstruction varies remarkably throughout daily life. 1
• Consultation with experienced HCM centers is reasonable when discussing septal reduction options. 4
• Low-intensity aerobic exercise is reasonable as part of a healthy lifestyle for HCM patients. 2, 3