What is the recommended initial management and follow‑up for a patient diagnosed with hypertrophic obstructive cardiomyopathy?

Management of Hypertrophic Obstructive Cardiomyopathy

Initial Medical Management

Beta-blockers are the first-line therapy for symptomatic hypertrophic obstructive cardiomyopathy (HOCM), titrated to maximum tolerated dose with the goal of achieving physiologic beta-blockade (suppressed resting heart rate). 1, 2

First-Line Pharmacotherapy

• Beta-blockers (non-vasodilating) should be initiated and titrated to maximum tolerated dose or until physiologic evidence of beta-blockade is achieved 1, 2, 3
• Verapamil or diltiazem (non-dihydropyridine calcium channel blockers) are reasonable alternatives if beta-blockers are not tolerated, though caution is required due to vasodilating properties 1, 2, 3
• Verapamil is contraindicated in patients with severe dyspnea at rest, hypotension, very high resting gradients (>100 mm Hg), and all children <6 weeks of age 1, 3

Second-Line Pharmacotherapy

• Disopyramide can be added to beta-blocker or calcium channel blocker therapy for persistent symptoms, requiring careful QTc monitoring and combination with an AV nodal blocking agent to prevent rapid ventricular response if atrial fibrillation develops 1, 4
• Mavacamten (cardiac myosin inhibitor) is recommended for adults with obstructive HCM who remain symptomatic despite first-line therapy, improving LVOT gradients, symptoms, and functional capacity in 30-60% of patients 1, 4

Critical Medications to Avoid

• Discontinue vasodilators (ACE inhibitors, ARBs, dihydropyridine calcium channel blockers) and digoxin as they worsen LVOT obstruction 1, 2
• Avoid positive inotropes that increase contractility and worsen obstruction 2
• Use diuretics cautiously at low doses only if signs of congestion are present, as aggressive diuresis decreases preload and augments LVOTO 1, 2

Invasive Treatment Indications

Septal reduction therapy (SRT) performed at experienced HCM centers is recommended for patients who remain symptomatic despite guideline-directed medical therapy (GDMT), with LVOT gradient ≥50 mm Hg at rest or with provocation. 1, 2

Eligibility Criteria for Septal Reduction Therapy

• Clinical: Severe dyspnea or chest pain (usually NYHA class III or IV), or occasionally syncope/near syncope attributable to LVOTO that interferes with everyday activity despite optimal medical therapy 1
• Hemodynamic: Dynamic LVOT gradient ≥50 mm Hg at rest or with physiologic provocation, associated with septal hypertrophy and systolic anterior motion (SAM) of mitral valve 1, 2
• Anatomic: Sufficient anterior septal thickness to perform the procedure safely 1

Choice of Invasive Procedure

• Surgical myectomy is the preferred treatment for most patients, particularly younger patients, those with extreme septal hypertrophy, or those with concomitant cardiac disease requiring surgical correction (anomalous papillary muscle, intrinsic mitral valve disease, multivessel CAD, valvular aortic stenosis) 1, 5
• Alcohol septal ablation is recommended for adult patients in whom surgery is contraindicated or risk is unacceptable due to serious comorbidities or advanced age 1, 6
• Earlier intervention (NYHA class II) may be reasonable in comprehensive HCM centers for patients with severe progressive pulmonary hypertension, left atrial enlargement with symptomatic AF episodes, poor functional capacity on exercise testing, or children/young adults with very high resting gradients (>100 mm Hg) 1

Contraindications to Invasive Therapy

• SRT is not recommended for asymptomatic patients with normal exercise capacity 1
• Mitral valve replacement should not be performed solely for relief of LVOTO when SRT is an option 1

Follow-Up and Monitoring

Annual comprehensive evaluation is recommended to assess disease progression, including echocardiography to monitor LVOT gradients and ventricular function. 3

Routine Surveillance

• Echocardiography to evaluate resting and provoked LVOT gradients, left ventricular function, and left atrial size 1, 2
• 48-hour ambulatory ECG monitoring every 6-12 months for patients with left atrial diameter ≥45 mm to detect atrial fibrillation 1
• Risk stratification for sudden cardiac death to determine need for implantable cardioverter-defibrillator 3, 7

Atrial Fibrillation Management

• Oral anticoagulation with direct oral anticoagulants or warfarin is recommended for all patients with HOCM and atrial fibrillation due to high stroke risk 1, 3
• Rate and rhythm control are key management objectives 3

Special Considerations

• Acute hypotension in HOCM is a medical urgency requiring maximization of preload and afterload with intravenous vasoconstrictors (phenylephrine), while avoiding increases in contractility or heart rate 1, 2
• Referral to specialized HCM centers should be considered for challenging treatment decisions, interpretation of symptoms, and consideration of advanced therapies 4, 3
• Screen for comorbidities including hypertension, obesity, metabolic factors, and sleep-disordered breathing, which contribute to symptom burden 4
• Cardiac transplantation should be considered for eligible patients with LVEF <50% and NYHA class III-IV symptoms despite optimal medical therapy or intractable ventricular arrhythmia 1