What are the clinical treatment guidelines for hypertrophic cardiomyopathy?

Clinical Treatment Guidelines for Hypertrophic Cardiomyopathy

Beta-blockers are the first-line pharmacological treatment for symptomatic patients with hypertrophic cardiomyopathy (HCM), followed by non-dihydropyridine calcium channel blockers for those who do not respond to or cannot tolerate beta-blockers. 1

Diagnostic Evaluation

• Initial evaluation should include comprehensive physical examination, complete medical history, and 3-generation family history 1
• Transthoracic echocardiography (TTE) is recommended for initial diagnosis and assessment of:
  • Degree of myocardial hypertrophy
  • Dynamic left ventricular outflow tract obstruction (LVOTO)
  • Mitral regurgitation
  • Myocardial function 1
• For patients with no change in clinical status, repeat TTE is recommended every 1-2 years 1
• Cardiovascular magnetic resonance (CMR) imaging is indicated when:
  • Echocardiography is inconclusive
  • There is suspicion of alternative diagnoses
  • Assessment of maximum LV wall thickness, ejection fraction, apical aneurysm, and myocardial fibrosis is needed 1

Management of Obstructive HCM

Pharmacological Treatment

• First-line therapy: Beta-blockers titrated to effectiveness or maximally tolerated doses for patients with symptoms attributable to LVOTO 1
• Second-line therapy: Non-dihydropyridine calcium channel blockers (verapamil, diltiazem) for patients who do not respond to or cannot tolerate beta-blockers 1
  • Verapamil should be used with caution in patients with high gradients, advanced heart failure, or sinus bradycardia 1
  • Verapamil is contraindicated in patients with severe dyspnea at rest, hypotension, very high resting gradients (>100 mm Hg), and in children <6 weeks of age 1
• Third-line therapy: Addition of disopyramide in combination with beta-blockers or calcium channel blockers for patients with persistent severe symptoms despite optimal therapy 1
• For acute hypotension in obstructive HCM, intravenous phenylephrine (or other pure vasoconstrictor) is recommended when patients do not respond to fluid administration 1

Invasive Treatment

• Septal reduction therapy (SRT) is recommended for severely symptomatic patients despite guideline-directed medical therapy 1
• Surgical myectomy is recommended when there is associated cardiac disease requiring surgical treatment (e.g., anomalous papillary muscle, elongated anterior mitral leaflet, intrinsic mitral valve disease) 1
• SRT should NOT be performed for asymptomatic patients with normal exercise tolerance 1

Management of Nonobstructive HCM with Preserved EF

• Beta-blockers or non-dihydropyridine calcium channel blockers are recommended for symptoms of exertional angina or dyspnea 1
• Oral diuretics can be added when exertional dyspnea persists despite beta-blockers or calcium channel blockers 1
• The usefulness of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers for symptom management is not well established 1

Management of HCM with Advanced Heart Failure

• For patients who develop systolic dysfunction with LVEF <50%, guideline-directed therapy for heart failure with reduced EF is recommended 1
• Diagnostic testing to assess for concomitant causes of systolic dysfunction (e.g., coronary artery disease) is recommended 1
• Heart transplantation assessment is indicated for patients with advanced heart failure refractory to medical therapy 1

Management of Atrial Fibrillation

• Anticoagulation with direct-acting oral anticoagulants (first-line) or vitamin K antagonists (second-line) is recommended for patients with clinical or subclinical AF >24 hours, independent of CHA₂DS₂-VASc score 1
• For rate control, beta-blockers, verapamil, or diltiazem are recommended based on patient preferences and comorbidities 1

Management of Ventricular Arrhythmias

• For symptomatic ventricular arrhythmias or recurrent ICD shocks despite beta-blocker use, antiarrhythmic drug therapy is recommended 1
• In patients with pacing-capable ICDs, programming antitachycardia pacing is recommended to minimize shock risk 1
• Catheter ablation can be useful for recurrent symptomatic sustained monomorphic ventricular tachycardia or recurrent ICD shocks despite optimal drug therapy 1

Lifestyle Considerations

• Low-intensity aerobic exercise is reasonable as part of a healthy lifestyle 1
• Comorbidities that may contribute to cardiovascular disease (hypertension, diabetes, hyperlipidemia, obesity) should be treated according to relevant guidelines 1
• For pregnant women with HCM, vaginal delivery is recommended as the first-choice delivery option 1
• Preconceptional and prenatal reproductive and genetic counseling should be offered to affected families 1

Common Pitfalls and Caveats

• The usefulness of beta-blockers and calcium channel blockers to alter clinical outcomes is not well established for asymptomatic patients 1
• Vasodilators (ACE inhibitors, ARBs, dihydropyridine calcium channel blockers) and digoxin may worsen symptoms in obstructive HCM and should be discontinued 1
• Routine SPECT MPI or stress echocardiography is not indicated for detection of "silent" CAD-related ischemia in asymptomatic patients 1
• Recent comparative data suggests that in low-risk HCM patients, verapamil therapy was not associated with higher adverse events compared to beta-blocker therapy, despite previous concerns 2