hypertrophic%20cardiomyopathy
HYPERTROPHIC CARDIOMYOPATHY

Hypertrophic cardiomyopathy is a genetically determined cardiac disorder characterized by hypertrophy, often of the left ventricle (LV), with nondilated ventricular chambers and no other cardiac or systemic disease (eg aortic stenosis, thyroid disease or hypertension) capable of producing the extent of hypertrophy manifested by the patient.

Symptoms can range from patients being asymptomatic to mildly or significantly symptomatic with pre-syncopal or syncopal episodes, palpitations, chest pain, decreased exercise tolerance, symptoms of pulmonary congestion (eg fatigue, dyspnea, orthopnea and paroxysmal nocturnal dyspnea) and symptoms of end-stage heart failure.

Approach to treatment is based on clinical experience and observational data as large randomized trials regarding medical therapy in hypertrophic cardiomyopathy are lacking.

An empiric therapy is often necessary to identify the best possible drug for the patient, starting at a low dose and titrating until clinical improvement or occurrence of side effects.

Treat comorbidities such as hypertension, diabetes, obesity and hyperlipidemia according to existing guidelines due to the significant influence of concomitant coronary artery disease on the survival of patients with hypertrophic cardiomyopathy.

 

Hypertrophic%20cardiomyopathy Treatment

Principles of Therapy

  • Approach to treatment is based on clinical experience and observational data as large randomized trials regarding medical therapy in HCM are lacking
  • An empiric therapy is often necessary to identify the best possible drug for the patient, starting at a low dose and titrating until clinical improvement or occurrence of side effects
  • Routine prophylactic treatment is not usually advised for asymptomatic patients
  • Treat comorbidities such as hypertension, diabetes, obesity and hyperlipidemia according to existing guidelines due to the significant influence of concomitant coronary artery disease on the survival of patients with HCM

Pharmacotherapy

Beta-Blockers

  • Eg Metoprolol, Propranolol
  • Preferred 1st-line agents for patients with obstructive disease and heart failure
    • May also be given to patients with non-obstructive disease
  • Negative inotropic agents that act by increasing diastolic filling and reducing contractility and provocable gradient; likelihood of peripheral vasodilation is low
  • Controls rate in patients with atrial fibrillation; combination with Amiodarone may suppress ventricular extrasystoles and non-sustained ventricular tachycardia
  • Treatment with beta-blockers decreases heart rates both at rest and with exertion and improves chest pain and dyspnea
    • Use with caution in patients with severe conduction disease or sinus bradycardia
  • Used to control symptoms during pregnancy, though increased monitoring is needed for development of fetal bradycardia or other complications

Calcium Channel Blockers (CCBs)

  • Non-dihydropyridine CCBs (eg Verapamil, Diltiazem) may be used as monotherapy (or when beta-blockers are not tolerated or contraindicated) or in combination with a beta-blocker in patients with significant heart failure and LVOTO despite treatment with a beta-blocker
    • May also be given to patients with non-obstructive disease
    • Decrease symptoms of angina by improving myocardial perfusion and control rate in patients with atrial fibrillation
    • Practice caution with use if with significant LVOT gradient or advanced heart failure; combination therapy with beta-blocker may lead to symptomatic bradycardia or AV block
  • Dihydropyridine CCBs are vasodilators that can lead to hypotension and/or worsening symptoms of heart failure resulting from the decrease in peripheral resistance and increase in LVOTO and thus should be avoided in patients with resting or provocable LVOTO

Disopyramide

  • Used in combination with a beta-blocker or a non-dihydropyridine CCB in patients with persistent heart failure and LVOTO symptoms despite treatment with a beta-blocker or a non-dihydropyridine CCB
  • An antiarrhythmic agent with negative inotropic properties, it reduces LV contractility, subaortic gradient, afterload, and resting and provocable gradient
  • Slows LV ejection acceleration
  • May cause prolongation of the QT interval and acceleration of the ventricular rate in the presence of atrial fibrillation or flutter
    • Avoid in patients with prostatic hypertrophy and those receiving class I antiarrhythmic drugs

Other Therapeutic Agents

Diuretics

  • Decrease in preload may aggravate LVOTO leading to hypotension and worsening symptoms, though when used cautiously, it can help patients with non-obstructive disease with persistent dyspnea despite treatment with beta-blockers or CCBs
  • To improve heart failure in NYHA class II-IV patients without LVOTO, consider low-dose loop and thiazide diuretics in those with preserved LVEF and low-dose loop diuretics in those with reduced LVEF

ACE Inhibitors and Angiotensin Receptor Blockers

  • Considered as alternative agents in the treatment of HCM patients with heart failure associated with decreased LVEF
  • Use with caution in patients with LVOTO at rest or with provocation

Antibiotic Prophylaxis

  • Infective endocarditis is a complication of HCM resulting from bacterial seeding in damaged cardiac valves or endocardium caused by turbulent blood flow
  • Though routine antibiotic prophylaxis is no longer recommended, benefits should be weighed against the risks of treatment, particularly with high-risk procedures in patients with congenital heart disease, prior endocarditis, or those with prosthetic cardiac valves

Thromboprophylaxis

  • Patients with HCM and chronic, paroxysmal or persistent atrial fibrillation are anticoagulated with vitamin K antagonists (VKA) (ie Warfarin); therapy is lifelong even with restoration of sinus rhythm
    • Oral anticoagulation also reduces risk of thromboembolism in patients with HCM and LV apical aneurysm
  • In patients who cannot or does not want to take oral anticoagulants, combination therapy with Aspirin and Clopidogrel should be considered
  • In patients who experience side effects of VKA, who are unable to undergo INR monitoring or who cannot take dose-adjusted VKA due to inability to maintain therapeutic anticoagulation, a direct thrombin inhibitor (eg Dabigatran) or factor Xa inhibitor (eg Apixaban, Rivaroxaban) may be used

Invasive Therapies

  • Indications for septal reduction therapy include the following:
    • Systolic anterior motion of the mitral valve resulting to obstructive disease
    • ≥50 mmHg LVOTO gradient at rest or on provocation
    • Anterior septal thickness >16 mm
    • Moderate to severe symptoms resistant to maximum medication treatment (eg recurrent pre-syncope or syncope or NYHA class III or IV)
      • In the asymptomatic patient, septal reduction therapy with either septal myectomy or alcohol septal ablation should not be carried out regardless of the severity of obstruction
    • Without contraindications to specific procedure
  • Several meta-analysis have demonstrated that both surgical myectomy and alcohol septal ablation improve patient's functional status with similar procedural mortality
    • However, choice of intervention will be based on assessment of the septal anatomy and mitral valve, concomitant cardiac problems and medical comorbidities, and patient preference, in consultation with an experienced multi-disciplinary team

Surgical Myectomy

  • Considered first in patients with LVOTO and symptoms resistant to treatment
  • Surgical candidates include patients with:
    • Absent to minimal comorbidities and are young
    • Baseline left bundle branch block
    • Diffuse or massive septal hypertrophy with several touch points to the papillary muscle or mitral valve leaflet
    • Significant intrinsic abnormality of the aortic or mitral valve
    • Coronary disease necessitating a surgical bypass or other lesions needing surgical intervention
  • Studies have shown a slightly better reduction in gradient compared with ablation; improvement in functional class and long-term outcomes are comparable
  • Disadvantages are the surgical risk involved and the longer hospital stay and recovery period including rehabilitation

Alcohol Septal Ablation

  • Echocardiography-guided direct injection of alcohol into a septal perforator artery creating a limited septal infarct or scar
    • Requires an acceptable anatomy of the coronary, septum and mitral valve
  • Alternative when surgical myectomy is contraindicated
  • May be performed in patients with:
    • Multiple or significant comorbidities and are older, ie >65 years old
    • Baseline right bundle branch block
    • A desire to avoid open heart surgery after an informed discussion
  • Successful ablation during the procedure shows at least a decrease of 50% in peak gradient or <20 mmHg residual gradient
  • Because of the risk of a complete heart block, patients are inserted with a pacemaker and monitored in the ICU for 48 hours

Dual Chamber (DDD) Pacing

  • Second-line invasive therapeutic option when other procedures have been declined, are contraindicated, or considered high risk
  • Randomized controlled trials had suggested a modest benefit when performed in patients >65 years old
  • May also be performed in patients with previously implanted dual chamber pacing device for non-HCM indications

Permanent Pacemaker Implantation

  • Performed in patients in whom conduction disease or bradycardia limits optimal medication treatment, symptomatic patients with obstructive HCM refractory to medication treatment, and patients with relative or absolute contraindications to septal reduction therapies

Heart Transplantation

  • Patients considered for heart transplantation are those with non-obstructive HCM, LVEF <50% and advanced heart failure not manageable with other treatment interventions (NYHA class III-IV) or intractable ventricular arrhythmia
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